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Chapter oneIntroduction to computer
What is computer?A computer is an electronic device capable of manipulating numbers and symbols taking an input, store it, processing it and giving an output, all under the control of a set of instruction called program.
Characteristics of a computer A computer is always characterizing by its speed, accuracy and massive storage capacity.Speed: the main feature of a computer is that it perform a lot of instruction with in a second .it speed is measured by millisecond -10-3second,Microsecond-10-
6second ,Nanosecond -10-9second and etc.Accuracy: it is accurate to retrieve information and follows a series of instruction that have been perfectly provided in the form of instruction.Reliability: Computer can reliably perform any problem or information given to them by the user as long as the circuitry system is perfectly designedMassive storage capacity: Computer Store large amount of information .you can store large amount of information or data on computer storage device.
Types of computerClassification of computer can be based on size, memory capacity and access time or the type of data that the computer processes.Classification according to their Size, Memory and Access time.
1. Microcomputer: is a single user, compact and its memory capacity is also low compare with others.Laptop, portable, desktop
2. Minicomputer: this kind of computer is multi-user .the size of this computer is greater than Microcomputer.
3. Mainframe computer: it is large computer and big institution or organization has this type of computer.
4. Supercomputer: very giant computer and is found only in few institution all over the world like NASA. Super computer process vas amount of information.
Computer SystemComputer system means the composition of computer. Computer system components are classified as hardware and software. The physical equipment that goes together to make up a computer is usually referred to as hardware.Hardware: is the part that you can touch .or the physical make up of the computer.Software: is the set of instruction called a program that directs the computer.
Computer Hardware Computer hardware is a collection of separate items working together as team. Some of these components are essential: others simply make working more pleasant and efficient. Adding extra item expands the variety of tasks you accomplish with your machine. Your hardware computer system is classified in to two parts:Main or basic components: parts of the hardware that must be present so that the computer performs its basic operator.
The system unit The monitor /display unit The keyboard Mouse
Optional part: it is the hardware that is optional but their presence makes our work more easier i.e. their absence doesn’t affect the basic operation of the computer.
Printer Scanner Speaker Modem
The main or basic part
The system unit: is the central component of your computer.
o Mother board: it is large circuit board that holds expansion slot and many different chips .Mother board houses the Microprocessor (CPU), computer memory and other essential chips. Most PC motherboard has slots, which accepts additional circuit board.
o Central processing unit (CPU): is also called ‘the heart of the computer’ or ‘the brain of the computer’ .The CPU performing two major functions. 1. It Co-ordinate and control the computers activity .for example retrieving files from disk ,interpreting data and commands entered from the keyboard, and sending data to a printer etc 2. It performs arithmetic and logical operations using the binary numbering system (ALU Arithmetic and Logical unit).
Computer System
Hardware Software
Optional part
Main Part Application Software OperatingSystem Software
o Computer memory: is used to store data or information .Any information inserted from input device is stored in memory. Computer data, that is information, has its own unit .The unit of data or information is Byte(or computer Memory is Expressed in Byte).One byte equal to a single character .The smallest unit of data is Binary Number-Equivalent to a single Zero or one).
1 Bit =1 character1 Byte=8 Bit1 Kilo Byte=1KB=1024Byte1 Mega Byte=1MB1 Giga Byte =1GB
Example Letter “A” is represented by the binary number 01000001
Computer memory is classified in to two parts
RAM (Random Access Memory) -temporary storage device All computer need memory to store data generated by the software .these integrated circuits (RAM) serve as temporary holding tanks for data. Other properties of RAM
It is working memory (area) with which CPU interacts for processing. It is power dependent-it store information depends on power i.e. it loses
information or its content when the power it off. You can delete, edit as well as read information that is store in it.
ROM (Read Only Memory )- Permanent storage device. Contains a small portion of programming .Its memory is permanent. Users or the computer can’t change it and its content remains the same even when the power to the computer is removed. The software contained on the ROM is basic input/output system and accommodates expansion hardware.
o Storage device Disks: are the most common form of permanent data storage device around magnetize plate usually made up of plastic or metal organized into concentric tracks and pie-shaped sector for storage data. Their are different types of disk Hard disk, floppy disk, CD-ROM disk.
o 1.Hard disk : are capable of storing large amount of data .Hard disk drive is much faster than floppy disk drive .It has a higher storage capacity .It can hold from 5MB to 80GB and above .Hard disk perform is measured in terms of access speed and transfer rate.
2. Floppy disk: perform the same basic function as hard disk and work much the same way. The most important difference is that hard disk cannot be inserting removed. It is used for storing relative small amount of information and also for transferring programs and data between one computer and another -5 ¼ inch in diameter disk can hold anywhere from 360 to 1.2 MB -3 ½ inch in diameter disk is capable of
[email protected] up to 2.88 MB of information .
o 3.CD-ROM: (compact disk read only memory) disk is a special kind of computer disk that store enormous amount of information ,A CD_ROM has many times the capacity of typical floppy disk yet transfer information at approximately the same speed as floppy disk.
Keyboard: is an input device that is used to type or entering information into the computer. Computer Keyboards are divided into five functional areas.
1. Typing Keys: work just like those on a conventional typewriter.2. Computer Keys: which are not found on the typewriters. They execute
special tasks when used alone or in combination with other keys.3. Functional Keys: perform different tasks depending on the software
being used.4. Dedicated cursor (Arrow Keys): are used to position the cursor on your screen.5. Numerical Keypad: let’s you either move the cursor or input numeric data.
The keyboard also has a status – indicator area .This area has three lights that display the status (on or off) of Num Lock, Caps Lock.
Monitor: It is display unit.
Optional part of Hardware
Scanner: is a device that enables to transform printer text or image into an electronic text or image. For example you can transfer any printable text or graphs like photos to computer data.
Printer: is a device that enables to transform an electronic text or image into printer text or image.
Modems and soon.
Computer SoftwareWhat is software?Software enables a computer to operate and perform tasks. Computer programs
are considered as software .Programs is detailed step-by-step instruction that tell a computer how to complete a specific task. They are written in programming languages such as Visual Basic, Pascal, and C++ .Without it, computer world is useless much like a camera without a film or a photograph with out records. The software used by computer falls into one of these Two-Category: System Software and Application Software
Operating System software: is as vital link between the computer hardware and application software. Without the operating system, application software would be unable to function. The operating system is
[email protected] to name, save, retrieve and maintain the program and data file you create and use on the computer.
Chapter TwoCase & Power Supply
System Unit Cases
System units may be packaged in a number of standard case designs. The key characteristics for case design include mounting methods for components,
ventilation characteristics, drive capacity, and footprint (desk space they take up).
Desktops
The most familiar PC case style is probably the desktop case design. These cases are designed to set horizontally on the desk (hence the name). Variations of the basic desktop design include narrow cases, referred to as baby AT cases,
and short desktops, called low-profile cases.
Towers Tower cases sit vertically on the floor beneath the desk. This case design came about to
free up workspace on the desktop. Tower cases offer extended drive bay capacities that make them especially useful in file
server applications where many disk, CD-ROM, and tape drive units may be desired. Although tower designs are convenient, their ventilation characteristics tend to be poor.
Adapter cards are mounted horizontally in tower units and the heat produced by the lower cards must rise past the upper cards, adding to their heat build up. To compensate for this problem, most tower cases include a secondary fan unit to increase airflow through the case and thereby dissipate more heat.
Mini towers and mid towers are short towers designed to take up less vertical space. Full towers are common in server machines.
Power Supplies
The system’s power-supply unit provides electrical power for every component
inside the system unit, as well as to the video display monitor.
It converts commercial electrical power received from a 120V AC, 60Hz (or 220V
AC, 50Hz) outlet into other levels required by the components of the system.
There are two basic types of power supplies: traditional AT power supplies
(designed to support AT-compatible system boards) and ATX power supplies
(designed according to newer ATX design specifications).
The AT power supply has two 6-pin system board power connectors (P8/P9),
whereas ATX power supplies use a single 20-pin power connector.
In the AT-compatible power supply, the cooling fan pulls air through the case from
the front and exhausts it out the rear of the power-supply unit.
Conversely, the ATX design pulls air in through the rear of the power-supply unit
and blows it directly on the ATX system board.
Voltages The desktop/tower power supply produces four (or five) different levels of efficiently
regulated DC voltage. These are +5V, –5V, +12V and –12V. (The ATX design also provides a +3.3V level to the
system board.) The power-supply unit also provides the system’s ground. The +5V level is used by the IC devices on the system board and adapter cards. The +3.3V
level is used by the microprocessor. The 12V levels are typically used to power the motors used in hard and floppy disk drives. System board power connectors provide the system board and the individual expansion
slots with up to 1 ampere of current each. The basic four voltage levels are available for use through the system board’s expansion slot connectors.
P8 & P9 Cables
In AT-compatible power supplies, two 6-wire bundles are typically marked P8 and P9. The physical construction of these power connectors significantly differs from that of the other bundles.
They are designed to be plugged into the system board’s P1 and P2 power plugs, respectively.
[email protected] good rule of thumb to remember when attaching
these two connectors to the system board is that the black wires in each bundle should be next to each other in the middle, as illustrated below.
Auxiliary Connectors
The other power-supply bundles are used to supply power to optional systems, such as the disk and CD-ROM drives.
Chapter ThreeATX POWER SUPPLY
In the ATX design, a special soft switch line is included that enables the system to shut itself off under control of the system software.
This allows power-management components of the operating system software to manage the hardware’s power usage.
Power-supply units come in a variety of shapes and power ratings. The shapes of the power supplies are determined by the type of case in
which they are designed to be used. The major difference between these two power-supply types is in their form factors.
The ATX power supply is somewhat smaller in size than the AT-style power supply, and their hole patterns differ.
The Power_Good Signal• Carried by the gray wire• +5v is generated by this wire if the internal circuitry of the PS is OK• This takes place 100ms to 500ms after we turn on the computer• In the absence of the power good signal the computer acts as if it’s
reset button is pressed
PS_ON and 5VSB
• PS_ON is carried by the green wire and 5v Standby is carried by the purple wire.
• A working ATX power supply should have these voltages without turning it on.
• These voltages enable features to be implemented, such as Wake on Ring or Wake on LAN, in which a signal from a modem or network adapter can actually cause a PC to wake up and power on.
ATX12
• In February 2000, Intel created the ATX/ATX12V power supply specification 1.0, adding an optional 4-pin +12V connector at the same time (those with the +12V connector were called ATX12V supplies).
• The ATX12V 2.0 specification (February 2003) dropped the 6-pin auxiliary connector, changed the main power connector to 24 pins, and made Serial ATA power connectors a requirement as well.
• See figure below on the main changes from normal ATX power supply.
Power Supply Specifications
• Wattage• Mean Time Between Failures (MTBF) or Mean Time To Failure (MTTF) - the
calculated average interval, in hours, that the power supply is expected to operate before failing.
• Input Range (or Operating Range). The range of voltages that the power supply is prepared to accept from the AC power source. For 220v current, a 180v–270v range is typical.
• Efficiency: The ratio of power input to power output, expressed in terms of a percentage. Values of 65%–85% are common for power supplies today.
Power Cycling• Should you turn off a system when it is not in use?• Frequently powering a system on and off does cause deterioration and
damage to the components.• It causes temperature or thermal shock.
èThermal expansion and contraction• Do not power the systems off for lunch, breaks, or any other short periods of
time.
[email protected] Supply Troubleshooting
The following is a list of PC problems that often are related to the power supply:■ Any power-on or system startup failures or lockups■ Spontaneous rebooting or intermittent lockups during normal operation■ Hard disk and fan simultaneously failing to spin (no +12v)■ Overheating due to fan failure■ Small brownouts that cause the system to reset■ Electric shocks felt on the system case or connectors■ Slight static discharges that disrupt system operation■ System that is completely dead (no fan, no cursor)■ Smoke■ Blown circuit breakers
Following is a simple flowchart to help you zero in on common power supply–related problems:1. Check the AC power input. Make sure the cord is firmly seated in the wall socket and in the power supply socket. Try a different cord.2. Check the DC power connections. Make sure the motherboard and disk drive power connectors are firmly seated and making good contact. Check for loose screws.3. Check the DC power output. Use a digital multi meter to check for proper voltages. If it’s below spec, replace the power supply.4. Check the installed peripherals. Remove all boards and drives and retest the system. If it works, add items back in one at a time until the system fails again. The last item added before the failure returns is likely defective
Power-Protection Systems
• They protect your equipment from the effects of power surges and power failures
• Most high-quality power supplies (or the attached systems) will not be damaged by the following occurrences:
■ Full power outage■ Any voltage drop (brownout)■ A spike of up to 2,500v
The following types of power-protection devices■ Surge suppressors■ Phone-line surge protectors■ Line conditioners■ Uninterruptible power supplies (UPS)
• Surge suppressors - can absorb the high-voltage transients produced by nearby lightning strikes and power equipment.
– Limited protectionPhone Line Surge Protectors
• In addition to protecting the power lines, it is critical to provide protection to your systems from any connected phone lines.
• In many areas, the phone lines are especially susceptible to lightning strikes, which are the leading cause of fried modems and damage to the computer equipment attached to them.
Line Conditioners (Stabilizers)
• It filters the power, bridges brownouts, suppresses high-voltage and current conditions, and generally acts as a buffer between the power line and the system.
• A line conditioner provides true power conditioning and can handle myriad problems.
• It contains transformers, capacitors, and other circuitry that can temporarily bridge a brownout or low-voltage situation.
Uninterruptible Power Supplies (UPS)
• The best overall solution to any power problem
• UPSs are known as online systems because they continuously function and supply power to your computer systems.
• In a true UPS, your system always operates from the battery. A voltage inverter converts from 12v DC to 110v AC. You essentially have your own private power system that generates power independently of the AC line.
• UPS cost is a direct function of both the length of time it can continue to provide power after a line current failure and how much power it can provide.
Chapter Four
Motherboards• Think of a motherboard as a scale model of a futuristic city with many
modular plug-in buildings, each using power from a common electrical system.
• The motherboard is the data and power infrastructure for the entire computer.
• Different motherboards of different vintages typically have different form factors.
• The form factor is essentially the size, shape and design of the actual motherboard.
Comparison of Form Factors
• This table is a summary comparison of the sizes of the various motherboard form factors, and compatibility factors.
Chipsets • We can't talk about modern motherboards without discussing chipsets. • The chipset is the motherboard; therefore, any two boards with the same chipsets
are functionally identical • The chipset usually contains the processor bus interface (called front-side
bus, or FSB), memory controllers, bus controllers, I/O controllers, and more. All the circuits of the motherboard are contained within the chipset.
• The chipset represents the connection between the processor and everything else. The processor can't talk to the memory, adapter boards, devices, and so on without going through the chipset. The chipset is the main hub and central nervous system of the PC.
• If you think of the processor as the brain, the chipset is the spine and central nervous system.
• Because the chipset controls the interface or connections between the processor and everything else, the chipset ends up dictating which type of processor you have; how fast it will run; how fast the buses will run; the speed, type, and amount of memory you can use; and more.
• Most earlier chipsets are broken into a multi tiered architecture incorporating what are referred to as North and South Bridge components, as well as a Super I/O chip.
– The North Bridge - So named because it is the connection between the high-speed processor bus (400/266/200/133/100/66MHz) and the slower AGP (533/266/133/66MHz) and PCI (33MHz) buses.
– The South Bridge - So named because it is the bridge between the PCI bus (66/33MHz) and the even slower ISA bus (8MHz).
– The Super I/O chip - It's a separate chip attached to the ISA bus that is not really considered part of the chipset. The Super I/O chip contains commonly used peripheral items all combined into a single chip.
• Note that most recent South Bridge chips now include Super I/O functions (such chips are known as Super-South Bridge chips), so that most recent motherboards no longer include a separate Super I/O chip.
Contents of Mother Board• Expansion Bus/Slots• RAM Banks• CPU socket/slot• Chipsets• Ports• IDE Interface/Controller• BIOS Chip• CMOS Battery
System Buses• The heart of any motherboard is the various buses that carry signals
between the components. A bus is a common pathway across which data can travel within a computer. This pathway is used for communication and can be established between two or more computer elements.
• Most of the internal system components, including the processor, cache, memory, expansion cards and storage devices, talk to each other over one or more "buses".
• The main buses in a modern system are as follows:– Processor bus. – AGP bus. – PCI-Express. – PCI bus. – ISA bus.
[email protected] Measurement
• Bus Width - A bus is a channel over which information flows. The wider the bus, the more information can flow over the channel, much as a wider highway can carry more cars than a narrow one. Bus width is measured in bits, we say 8-bits wide or 32-bits wide etc.
• Bus Speed - The speed of the bus reflects how many bits of information can be sent across each wire each second. This would be analogous to how fast the cars are driving on our analogical highway). Bus speed is measured in Hertz, typically in MHz.
• Bus Bandwidth, also called throughput, refers to the total amount of data that can theoretically be transferred on the bus in a given unit of time. Using the highway analogy, if the bus width is the number of lanes, and the bus speed is how fast the cars are driving, then the bandwidth is the product of these two and reflects the amount of traffic that the channel can convey per second.
The table below shows the theoretical bandwidth of most of the common I/O buses on PCs todayThe table below shows the theoretical bandwidth of most of the common I/O buses on PCs today
Bus Hierarchy• Processor bus - Also called the front-side bus (FSB), this is the highest-
speed bus in the system and is at the core of the chipset and motherboard. This bus is used primarily by the processor to pass information to and from cache or main memory and the North Bridge of the chipset. The processor
bus in a modern system runs at 66MHz, 100MHz, 133MHz, 200MHz,
[email protected], 400MHz, 533MHz, 800MHz, or 1066MHz and is normally 64 bits
(8 bytes) wide.• AGP bus - This is a 32-bit bus designed specifically for a video card. It runs
at 66MHz (AGP 1x), 133MHz (AGP 2x), 266MHz (AGP 4x), or 533MHz (AGP 8x), which allows for a bandwidth of up to 2133MBps. It is connected
to the North Bridge or Memory Controller Hub of the chipset and is manifested as a single AGP slot in systems that support it. Newer systems
are phasing out AGP slots in favor of PCI-Express.• PCI-Express -The PCI-Express bus is a third-generation development of
the PCI bus. The speed of PCI-Express is described in terms of lanes. Each bidirectional dual-simplex lane provides a 2.5Gbps transfer rate in each direction (2Gbps effective speed). Thus a single-lane PCI-Express slot
(known as x1) runs at 2.5Gbps in each direction. Some systems support PCI-Express x4, which provides 10Gbps in each direction. PCI-Express video cards generally use the x16 slot, which provides 40Gbps in each
direction.
• PCI bus - This is usually a 33MHz 32-bit bus found in virtually all systems since the days of the Intel 486 CPU. This bus is generated by either the chipset North Bridge in North/South Bridge chipsets or the I/O Controller
Hub in chipsets using hub architecture. This bus is manifested in the system as a collection of 32-bit slots, normally white in color and numbering from four to six on most motherboards. High-speed peripherals, such as SCSI adapters, network cards, video cards, and more, can be plugged into PCI
bus slots.
• ISA bus - This is an 8MHz 16-bit bus that has disappeared from recent systems after first appearing in the original PC in 1984. It is a very slow-
speed bus, but it was ideal for certain slow-speed or older peripherals. It has been used in the past for plug-in modems, sound cards, and various other low-speed peripherals. The ISA bus is created by the South Bridge part of
the motherboard chipset, which acts as the ISA bus controller and the interface between the ISA bus and the faster PCI bus above it. The Super
I/O chip usually was connected to the ISA bus on systems that included ISA slots.
Expansion Slots• The I/O bus or expansion slots enable your CPU to communicate with
peripheral devices. The bus and its associated expansion slots are needed because basic systems can't possibly satisfy all the needs of all the people who buy them.
• The I/O bus enables you to add devices to your computer to expand its capabilities.
• The most basic computer components, such as sound cards and video cards, can be plugged into expansion slots .
•Types of I/O Buses
• You can identify different types of I/O buses by their architectures. • The main differences among buses consist primarily of the amounts of data
they can transfer at one time and the speeds at which they can do it. The following sections describe the various types of PC buses.
• These are:– ISA
– EISA– PCI– AGP
– PCI-Express
[email protected]. Industry Standard Architecture (ISA) Bus
– One of the oldest bus– Slow performance (8-bits wide and runs at 16MHz max)– Obsolete nowadays
2. Extended Industry Standard Architecture (EISA) Bus– Developed by Compaq– Didn’t become as popular as ISA because of its proprietary nature– key features of the EISA bus:
• ISA Compatibility: ISA cards will work in EISA slots. • 32 Bit Bus Width • Plug and Play
Expansion Slots on Modern Motherboards
3. Peripheral Component Interconnect (PCI) Local Bus
• Currently by far the most popular local I/O bus• developed by Intel and introduced in 1994 • high performance general I/O bus due to several factors
– Burst Mode– Bus Mastering– High Bandwidth Options
• The PCI bus offers a great variety of expansion cards
4. Accelerated Graphics Port (AGP)• To combat the eventual saturation of the PCI bus with video information, a
new interface has been pioneered by Intel, designed specifically for the video subsystem.
• 3D acceleration and full-motion video playback were possible• Addressed the requirement for large memory by accessing the main system
RAM• AGP is considered a port, and not a bus, because it only involves two
devices (the processor and video card) and is not expandable. • Dedicated only for video cards• Has improved speeds like 2X, 4X and 8X.
[email protected] Slot
AGP Slot5. PCI Express
• PCI Express is now destined to be the dominant PC bus architecture designed to support the increasing bandwidth needs in PCs over the next 10–15 years.
• PCI Express is another example of how the PC is moving from parallel to serial interfaces.
• PCI Express is a very fast serial bus design that is backward-compatible with current PCI parallel bus software drivers and controls.
• PCI Express is designed to augment and eventually replace many of the buses currently used in PCs.
• Up to 4000MBps bandwidth.
Chapter Five
PortsI/O Interfaces
[email protected] Serial and Parallel Ports
Traditionally, the most basic communications ports in any PC system have been the serial and parallel ports, and these ports continue to be important.
Serial ports (also known as communication or COM ports) originally were used for devices that had to communicate bidirectional with the system.
Such devices include modems, mice, and scanners. Newer parallel port standards now allow the parallel port to perform high-
speed bidirectional communications.Serial Ports
The asynchronous serial interface was designed as a system-to-system communications port.
Bit-by-bit communication Each bit lines up in a series to be sent. built-in serial ports are controlled by a Super I/O chip The interface is a DB-9 or DB-25 male connector
DB-9 male connector
DB-25 male connector DB-25 male connector
UARTs The heart of any serial port is the Universal Asynchronous
Receiver/Transmitter (UART) chip. This chip completely controls the process of breaking the native parallel data
within the PC into serial format and later converting serial data back into the parallel format.
The high-speed 16550 UART chip is the widely used one. Most 16550 UARTs have a maximum communications speed of 115Kbps. Newer UARTs include 16650, 16750, and 16850 chips. These chips with larger-buffered versions allow speeds of 230Kbps (16650),
460Kbps (16750), and 920Kbps (16850) and are recommended when running a high-speed external communications link such as an ISDN terminal adapter or external 56Kbps modem.
Testing Serial Ports
The two most common types of tests are those that involve software only and those that involve both hardware and software.
The software only tests are done with diagnostic programs, such as Microsoft’s MSD or the Modem diagnostics built into Windows, whereas the hardware and software tests involve using a wrap plug to perform loopback testing.
For software diagnostics read pages 983-984 on your text.
Loopback Testing
Loopback tests are basically internal (digital) or external (analog). The external loopback test is more effective. This test requires that a special loopback connector or wrap plug be
attached to the port in question. When the test is run, the port is used to send data out to the loopback plug,
which simply routes the data back into the port’s receive pins so the port is transmitting and receiving at the same time.
9-Pin Serial Port Connector
Constructing wrap plugs the wiring necessary to construct your own serial port loopback or wrap
plugs: For the standard 9-pin serial (female DB9S) loopback connector (wrap plug),
connect the following pins: 1 to 7 to 8 2 to 3 4 to 6 to 9
Plug the wrap plug and run diagnostics software.Parallel Ports
normally used for connecting printers to a PC. Parallel ports are so named because they have eight lines for sending all the
bits that comprise 1 byte of data simultaneously across eight wires. The only problem with parallel ports is that their cables can’t be extended for
any great length. Interface is DB-25 female.
Parallel Port Modes
Linking Systems with Serial or Parallel Ports
You can connect two systems locally using their serial or parallel ports along with specially wired cables.
Even though this method is slow it can be especially useful when you are migrating your data to a new system you have built or purchased.
Several free and commercial programs can support serial or parallel-port file transfers.
MS-DOS 6.0 and later include a program called Interlink, whereas Windows 95 and later include software called Direct Cable Connection.
The most famous third-party software is Lap link.
Null Modem Cable Construction
Universal Serial Bus (USB)
Uses serial communication. Why Serial, why not parallel?
Increasing the clock speed of a serial connection is much easier than increasing that of a parallel connection.
Parallel connections in general suffer from several problems, the biggest being signal skew and jitter.
skew and jitter are data corruptions due to long distance and high speed propagation.
With a serial bus, the data is sent 1 bit at a time (no worry about when each bit will arrive; the clocking rate can be increased dramatically).
Parallel cabling is more expensive than serial cabling.
USB
[email protected] Brings Plug and Play (PnP) capability for attaching peripherals externally to
the PC. saves important system resources such as interrupts (IRQs) Regardless of the number of devices attached to a system’s USB ports, only
one IRQ is required. allows up to 127 devices to run simultaneously on a single bus Has two versions
USB 1.1 and USB 2.0 (Hi-Speed USB)USB Technical Details
USB 1.1 runs at 12Mbps (1.5MBps) over a simple four-wire connection. Note that although the standard allows up to 127 devices to be attached,
they all must share the 1.5MBps bandwidth, meaning that for every active device you add, the bus will slow down some.
USB devices are considered either hubs or functions, or both. Functions are the individual devices that attach to the USB, such as a
keyboard, mouse, camera, printer, telephone, and so on. Hubs provide additional attachment points to the USB, enabling the
attachment of more hubs or functions.
USB 2.0 USB 2.0 is a backward-compatible extension of the USB 1.1 uses the same cables, connectors, and software interfaces, but it runs 40
times faster than the original 1.1 version. The higher speed enables higher-performance peripherals, such as higher-
resolution Web/videoconferencing cameras, scanners, and faster printers. All existing USB 1.1 devices work in a USB 2.0
USB Adapters
[email protected] If you still have a variety of older peripherals and yet you want to take
advantage of the USB connector on your motherboard, several signal converters or adapters are available.
■ USB-to-parallel (printer)■ USB-to-serial■ USB-to-SCSI■ USB-to-Ethernet■ USB-to-keyboard/mouse■ USB-to-TV/video■ USB-to-PS/2
Enabling USB Support What if an old system does not have USB support? Install USB expansion card that plug into the PCI slot.
1. Card brackets are used when there is no USB output port on the motherboard.
2. They can also be installed at the front to give easy access to USB ports.Hubs
Hubs are essentially wiring concentrators, and through a star-type topology they allow the attachment of multiple devices.
VGA Connectors
[email protected] DB-15 (5 pins in 3 rows) female connector and DVI connector Used only for connecting Monitors (output only)
VGA Card
[email protected]/Mouse Interface Connectors
5-pin DIN connector - Used on most PC systems with Baby-AT form factor motherboards
6-pin mini-DIN connector (PS/2) - Used on most PCs with ATX motherboards
Network Interface Card (NIC) RJ-45 – used for connecting PCs via NIC 8 pins
Modem Connections RJ-11 – used for connecting telephone lines to modem Max. 4 pins
Chapter Six
BIOSOverview
BIOS is a term that stands for basic input/output system, which at the most basic level consists of low level software that controls the system hardware.
BIOS is essentially the link between hardware and software in a system. BIOS code is burned or flashed into a ROM chip that is both nonvolatile and
read-only.PC System Layers
A PC system can be described as a series of layers—some hardware and some software—that interface with each other. In the most basic sense, you can break a PC down into four primary layers, each of which can be broken down further into subsets.
The purpose of the layered design is to enable a given operating system and applications to run on different hardware. The figure shows how two different machines with different hardware can each use different drivers (BIOS) to interface the unique hardware to a common operating system and applications.
The hardware layer is where most differences lie between various systems. It is up to the BIOS to mask the differences between unique hardware so that the given operating system (and subsequently the application) can be run.
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BIOS Hardware/Software
The BIOS itself is software running in memory that consists of all the various drivers that interface the hardware to the operating system.
The BIOS in a PC comes from three possible sources:■ Motherboard ROM■ Adapter card ROM (such as that found on a video card)■ Loaded into RAM from disk (device drivers)
The motherboard BIOS usually includes drivers for all the basic system components, including the keyboard, floppy drive, hard drive, serial and parallel ports, and more.
As systems became more complex, new hardware was added for which no motherboard BIOS drivers existed.
Rather than requiring a new motherboard BIOS that would specifically support the new devices, it was far simpler and more practical to copy any new drivers that were necessary onto the system hard disk and configure the operating system to load them at boot time.
This is how most CD-ROM drives, sound cards, scanners, printers, and so on are supported.
BIOS and CMOS RAM Some people confuse BIOS with the CMOS RAM in a system. The BIOS on the motherboard is stored in a fixed ROM chip. Also on the motherboard there is a chip called the RTC/NVRAM chip, which
stands for real-time clock/nonvolatile memory. This is where the BIOS Setup information is stored, and it is actually a digital clock chip with a few extra bytes of memory.
It is usually called the CMOS chip because it is made using CMOS (complimentary metal-oxide semiconductor) technology.
When you enter your BIOS Setup, configure your hard disk parameters or other BIOS Setup settings, and save them, these settings are written to the storage area in the RTC/NVRAM (otherwise called CMOS RAM) chip.
Every time your system boots up, it reads the parameters stored in the CMOS RAM chip to determine how the system should be configured.
A relationship exists between the BIOS and CMOS RAM, but they are two distinctly different parts of the system.
Motherboard BIOS The BIOS is a collection of programs embedded in one or more chips,
depending on the design of your computer. That collection of programs is the first thing loaded when you start your computer, even before the operating system.
The BIOS in most PCs has four main functions:■ POST (power on self test). The POST tests your computer’s processor, memory, chipset, video adapter, disk controllers, disk drives, keyboard, and other crucial components.■ Setup. The system configuration and setup program is usually a menu-driven program activated by pressing a special key during the POST, and it enables you to configure basic system settings. ■ Bootstrap loader. A routine that reads the disk drives looking for a valid master boot sector. This master boot sector program then continues the boot process by loading an operating system boot sector, which then loads the operating system core files.■ BIOS (basic input/output system). This refers to the collection of actual drivers used to act as a basic interface between the operating system and your hardware when the system is booted and running.
ROM BIOS Manufacturers Several popular BIOS manufacturers in the market today supply the majority
of motherboard and system manufacturers with the code for their ROMs. Several companies have specialized in the development of a compatible
ROM BIOS product. The three major companies that come to mind in discussing ROM BIOS
software are American Megatrends, Inc. (AMI), Phoenix Technologies, and Award Software (now owned by Phoenix Technologies).
Many OEMs (original equipment manufacturer) have developed their own compatible ROMs independently. Companies such as Compaq, AT&T, and Acer have developed their own BIOS products that are comparable to those offered by AMI, Phoenix, Award, and others.
Most OEMs have their BIOS written for them by a third-party company. For example, Hewlett-Packard contracts with Phoenix to develop the motherboard BIOSes for some HP PCs.
EEPROM/Flash ROM Modern BIOS is made of EEPROM. By using an EEPROM, or flash ROM, you can erase and reprogram the
motherboard ROM in a PC without removing the chip from the system or even opening up the system chassis.
In most cases, you download the updated ROM from the motherboard manufacturer’s Web site and then run a special program it provides to update the ROM.
[email protected] An updated BIOS might contain bug fixes or enable new features not originally
found in your system.
Upgrading the BIOS
A simple BIOS upgrade can often give your computer better performance and more features.
The following list shows the primary functions of a ROM BIOS upgrade:■ Adding LS-120 (120MB) floppy drive support (also known as a SuperDisk)■ Adding support for hard drives greater than 8GB■ Adding support for Ultra-DMA/33, UDMA/66, or UDMA/100 IDE hard drives■ Adding support for bootable ATAPI CD-ROM drives ■ Adding or improving Plug and Play (PnP) support and compatibility■ Correcting calendar-related and leap-year bugs■ Correcting known bugs or compatibility problems with certain hardware and application or operating system software■ Adding support for newer-type and -speed processors■ Adding support for ACPI power management
If you install newer hardware or software and follow all the instructions properly, but you can’t get it to work, specific problems might exist with the BIOS that an upgrade can fix.
Beep Codes Whenever a POST fails the BIOS may indicate the error through a blank screen, or a
visual error message on the video display, or through an audio response (beep codes) produced by the system’s speaker.
Different beep codes are generated depending on the device which has failed to respond to the POST. This translation between beep codes and the device involved is primarily referred from the mainboard’s manual.
If every device tested is operating correctly a single beep sound is heard. In PCs, you can use the single beep that most PCs produce between the end of the POST
and the beginning of the boot-up process to separate hardware problems from software problems.
Errors that occur, or are displayed, before this beep indicate that a hardware problem of some type exists. This conclusion should be easy to understand because up to this time, only the BIOS and the basic system hardware have been active. The operating system side of the system does not come into play until after the beep occurs.
If the system produces an error message or a beep code before the single beep, for example, the system has found a problem with the RAM hardware.
Example Here’s an example of beep codes produced by a particular BIOS version from
American Megatrends (AMI)
Chapter SevenMemory
Memory Basics Memory is the workspace for the computer’s processor. It is a temporary storage area
where the programs and data being operated on by the processor must reside. Memory storage is considered temporary because the data and programs remain there only
as long as the computer has electrical power or is not reset. Before being shut down or reset, any data that has been changed should be saved to a more
permanent storage device (usually a hard disk) so it can be reloaded into memory in the future.
RAM Memory often is called RAM, for random access memory.
you can randomly (as opposed to sequentially) access any location in memory. This designation is somewhat misleading and often misinterpreted. Read-only memory (ROM), for example, is also randomly accessible, yet is usually
differentiated from the system RAM because it maintains data without power and can’t normally be written to. Disk memory is also randomly accessible, but we don’t consider that RAM either.
Dynamic RAM and Static RAM RAM can be made of DRAM or SRAM chips. One of the characteristics of DRAM chips is that they store data dynamically,
which really has two meanings. One meaning is that the information can be written to RAM repeatedly at any
time. The other has to do with the fact that DRAM requires the data to be refreshed (essentially rewritten) every 15ms (milliseconds) or so.
A type of RAM called static RAM (SRAM) does not require the periodic refreshing. An important characteristic of RAM in general is that data is stored only as long as the memory has electrical power.
Memory Analogy People new to computers often confuse main memory (RAM) with disk
storage because both have capacities that are expressed in similar megabyte or gigabyte terms. The best analogy to explain the relationship between memory and disk storage is to think of an office with a desk and a file cabinet.
The file cabinet represents the system’s hard disk, where both programs and data are stored for long-term safekeeping. The desk represents the system’s main memory, which allows the person working at the desk (acting as the processor) direct access to any files placed on it.
[email protected] RAM chips are sometimes termed volatile storage because when you
turn off your computer or an electrical outage occurs, whatever is stored in RAM is lost unless you saved it to your hard drive.
Physical Memory Physically, the main memory in a system is a collection of chips or
modules containing chips that are usually plugged into the motherboard. Three main types of physical memory are used in modern PCs:
■ ROM. Read-only memory■ DRAM. Dynamic random access memory■ SRAM. Static RAM
ROM
Read-only memory, or ROM, is a type of memory that can permanently or semi permanently hold data. It is called read-only because it is either impossible or difficult to write to.
ROM also is often referred to as nonvolatile memory because any data stored in ROM remains there, even if the power is turned off.
ROM is an ideal place to put the PC’s startup instructions. Note that ROM and RAM are not opposites, as some people seem to
believe. The main ROM BIOS is contained in a ROM chip on the motherboard, but
there are also adapter cards with ROMs on them as well. Most systems today use a type of ROM called electrically erasable
programmable ROM (EEPROM), which is a form of Flash memory.
DRAM Dynamic RAM (DRAM) is the type of memory chip used for most of the main
memory in a modern PC. The main advantages of DRAM are that it is very dense, meaning you can
pack a lot of bits into a very small chip, and it is inexpensive, which makes purchasing large amounts of memory affordable.
The memory cells in a DRAM chip are tiny capacitors that retain a charge to indicate a bit. If the capacitor is charged, the cell is read to contain a 1; no charge indicates a 0. The charge in the tiny capacitors is constantly draining, which is why the memory must be refreshed constantly.
Refreshing the memory unfortunately takes processor time away from other tasks because each refresh cycle takes several CPU cycles to complete.
DRAM is used in PC systems because it is inexpensive and the chips can be densely packed, so a lot of memory capacity can fit in a small space.
[email protected] Unfortunately, DRAM is also slow, typically much slower than the
processor. For this reason, many types of DRAM architectures have been developed to improve performance.
Cache Memory: SRAM
SRAM stands for static RAM, which is so named because it does not need the periodic refresh rates like DRAM. SRAM is much faster than DRAM and fully capable of keeping pace with modern processors.
SRAM memory is available in access times of 2ns or less, so it can keep pace with processors running 500MHz or faster!
The SRAM design calls for a cluster of six transistors for each bit of storage. The use of transistors but no capacitors means that refresh rates are not necessary because there are no capacitors to lose their charges over time.
So, why don’t we use SRAM for all system memory? Compared to DRAM, SRAM is much faster but also much lower in
density and much more expensive. The lower density means that SRAM chips are physically larger and
store fewer bits overall.
DRAM vs SRAM Basically, SRAM is up to 30 times larger physically and up to 30 times more
expensive than DRAM. The high cost and physical constraints have prevented SRAM from being
used as the main memory for PC systems.
CPU Cache Even though SRAM is too expensive for PC use as main memory, PC designers
have found a way to use SRAM to dramatically improve PC performance. SRAM memory, which can run fast enough to match the CPU, can be used as a
high speed memory, called cache memory. The cache runs at speeds close to or even equal to the processor and is the
memory from which the processor usually directly reads from and writes to. During read operations, the data in the high-speed cache memory is re-supplied
from the lower-speed main memory or DRAM in advance. Up until recently, DRAM was limited to about 60ns (16MHz) in speed which cannot
cope up with the fast CPU speed. Cache effectiveness is expressed as a hit ratio. This is the ratio of cache hits to
total memory accesses.
[email protected] A hit occurs when the data the processor needs has been preloaded into the
cache from the main memory, meaning the processor can read it from the cache. A cache miss is when the cache controller did not anticipate the need for a specific address and the desired data was not preloaded into the cache. In that case the processor must retrieve the data from the slower main memory, instead of the faster cache.
L1 and L2 Cache
To minimize the processor being forced to read data from the slow main memory, two stages of cache usually exist in a modern system, called Level 1 (L1) and Level 2 (L2).
The L1 cache is also called integral or internal cache because it is directly built into the processor and is actually a part of the processor die (raw chip).
Because of this, L1 cache always runs at the full speed of the processor core and is the fastest cache in any system.
L2 cache is also called external cache because it is external to the processor chip.
Originally, this meant it was installed on the motherboard, as was the case with all 386, 486, and Pentium systems. In those systems, the L2 cache runs at motherboard speed because it is installed on the motherboard.
In the interest of improved performance, later processor designs from Intel and AMD have included the L2 cache as a part of the processor.
On board, on chip & on die cache Cache speed is very important, so systems having L2 cache on the
motherboard were the slowest. Including L2 inside the processor made it faster, and including it directly on the processor die (rather than as chips external to the
die) is the fastest yet. The new Itanium processor from Intel has three levels of cache within the
processor module for even greater performance.
RAM Memory TypesMHz to ns
The speed and performance issue with memory is confusing to some because memory speed is usually expressed in ns (nanoseconds) and processor speed has always been expressed in MHz (megahertz).
Fortunately, you can translate one to the other. To convert access time in nanoseconds to MHz, use the following formula:
1 / nanoseconds × 1000 = MHz Likewise, to convert from MHz to nanoseconds, use the following inverse
formula: 1 / MHz × 1000 = nanoseconds
Fast Page Mode DRAM DRAM is accessed through a technique called paging. Paging enables faster access to all the data within a given row of memory by
keeping the row address the same and changing only the column. Memory that uses this technique is called Page Mode or Fast Page Mode
memory. Paged memory is a simple scheme for improving memory performance that
divides memory into pages ranging from 512 bytes to a few kilobytes long. To improve further on memory access speeds, systems have evolved to
enable faster access to DRAM. One important change was the implementation of burst mode access in the
486 and later processors.Burst Mode
[email protected] Burst mode cycling takes advantage of the consecutive nature of most
memory accesses. After setting up the row and column addresses for a given access, using
burst mode, you can then access the next three adjacent addresses with no additional latency or wait states.
A typical burst mode access of standard DRAM is expressed as x-y-y-y; x is the time for the first access (latency plus cycle time), and y represents the number of cycles required for each consecutive access.
DRAM memory that supports paging and this bursting technique is called Fast Page Mode (FPM) memory.
Most 486 and Pentium systems from 1995 and earlier use FPM memory.Interleaving
Another technique for speeding up FPM memory was called interleaving.
In this design, two separate banks of memory are used together, alternating access from one to the other as even and odd bytes.
While one is being accessed, the other is being precharged. Then, by the time the first bank in the pair is finished returning data, the second bank is now ready to return data.
This overlapping of accesses in two banks reduces the effect of the latency or precharge cycles and allows for faster overall data retrieval.
The only problem is that to use interleaving, you must install identical pairs of banks together, doubling the amount of SIMMs or DIMMs required.
FPM RAM
FPM RAM Module is 30 pin, 8-bits wide.
Extended Data Out RAM In 1995, a newer type of memory called extended data out (EDO) RAM became
available for Pentium systems.
[email protected] EDO, a modified form of FPM memory, is sometimes referred to as Hyper Page
mode. The name extended data out refers specifically to the fact that unlike FPM, the data
output drivers on the chip are not turned off when the memory controller removes the column address to begin the next cycle.
This enables the next cycle to overlap the previous one, saving approximately 10ns per cycle.
EDO RAM allows for burst mode cycling of 5-2-2-2, compared to the 5-3-3-3 of standard fast page mode memory.
With EDO you didn’t need to install two identical banks of memory in the system at a time.
EDO RAM EDO RAM generally comes in 72-pin SIMM form, and it is 32-bit wide. EDO RAM is ideal for systems with bus speeds of up to 66MHz, which fit
perfectly with the PC market up through 1997.
SDRAM SDRAM is short for synchronous DRAM, a type of DRAM that runs in
synchronization with the memory bus. SDRAM delivers information in very high-speed bursts using a high-speed,
clocked interface. SDRAM removes most of the latency involved in asynchronous DRAM
because the signals are already in synchronization with the motherboard clock. SDRAM timing for a burst access would be 5-1-1-1, meaning that four
memory reads would complete in only eight system bus cycles, compared to eleven cycles for EDO and fourteen cycles for FPM.
Besides being capable of working in fewer cycles, SDRAM is also capable of supporting up to 133MHz (7.5ns) system bus cycling.
As such, most new PC systems sold in 1998, and through 2000, have included SDRAM memory.
[email protected] Module
DDR SDRAM Double data rate (DDR) SDRAM memory is an evolutionary design of
standard SDRAM in which data is transferred twice as quickly. Instead of doubling the actual clock rate, DDR memory achieves the doubling in
performance by transferring twice per transfer cycle. DDR found most of its initial support in the graphics card market and since then
has become the mainstream PC memory standard. DDR SDRAM uses a new DIMM module design with 184 pins.
DDR Module
DDR2
DDR2 SDRAM is simply a faster version of conventional DDR-SDRAM memory: It achieves higher throughput by using differential pairs of signal wires to allow faster signaling without noise and interference problems.
DDR2 is still double data rate just as with DDR, but the modified signaling method enables higher speeds to be achieved with more immunity to noise and cross-talk between the signals.
The additional signals required for differential pairs add to the pin countDDR2 DIMMs have 240 pins, which is more than the 184 pins of DDR. The original DDR specification tops out at 400MHz, whereas DDR2 starts at 400MHz and goes up to 1000MHz and beyond.
In addition to providing greater speeds and bandwidth, DDR2 has other advantages. It uses lower voltage than conventional DDR (1.8V versus 2.5V), so power consumption and heat generation are reduced.
DDR2 DIMMs resemble conventional DDR DIMMs but have more pins and slightly different notches to prevent confusion or improper application.
RDRAM Rambus DRAM (RDRAM) is a fairly radical memory design found in
high-end PC systems starting in late 1999. Conventional memory systems that use FPM/EDO or SDRAM are known
as wide-channel systems. They have memory channels as wide as the processor’s data bus, which for the Pentium and up is 64 bits.
RDRAMs, on the other hand, are narrow-channel devices. They transfer data only 16 bits (2 bytes) at a time (plus 2 optional parity bits), but at much faster speeds.
[email protected] This is a shift away from a more parallel to a more serial design and is
similar to what is happening with other evolving buses in the PC. 16-bit single channel RIMMs originally ran at 800MHz, so the overall
throughput is 800×2, or 1.6GB per second for a single channel—the same as PC1600 DDR SDRAM.
RDRAM TypesNewer RIMM versions run at 1066MHz or 1200MHz in addition to the original 800MHz rate and are available in single-channel, 16-bit versions as well as multiple-channel, 32-bit and 64-bit versions for throughputs up to 9.6GB/sec per module.
RDRAM Module
The main consideration for memory is that the throughput of the memory bus should match the throughput of the processor bus, and in that area RDRAM RIMMs are much more suited to the faster Intel Pentium 4 processor systems.
Chapter EightMicroprocessors
Overview The brain or engine of the PC is the processor (sometimes called
microprocessor), or central processing unit (CPU). The CPU performs the system’s calculating and processing. The processor
is often the most expensive single component in the system (although graphics card pricing now surpasses it in some cases); in higher-end
[email protected] it can cost up to four or more times more than the motherboard it plugs into.
Intel and AMD are the well know processor manufacturers.Processor Specifications
Processors can be identified by two main parameters: how wide they are and how fast they are.
The width of a processor is a little more complicated to discuss because three main specifications in a processor are expressed in width. They are
■ Data I/O bus■ Internal registers■ Address bus
Data I/O Bus The processor bus discussed most often is the external data bus—the
bundle of wires (or pins) used to send and receive data. The more signals that can be sent at the same time, the more data can be
transmitted in a specified interval and, therefore, the faster (and wider) the bus. A wider data bus is like having a highway with more lanes, which enables
greater throughput. All modern processors from the original Pentium through the latest Pentium
4, AMD Athlon, and even the Itanium have a 64-bit (8-byte) wide data bus. Therefore, they can transfer 64 bits of data at a time to and from the motherboard chipset or system memory.
Another ramification of the data bus in a chip is that the width of the data bus also defines the size of a bank of memory. So, a processor with a 32-bit data bus such as the 486, reads and writes memory 32 bits at a time.
Because standard 72-pin single inline memory modules (SIMMs) are only 32 bits wide, they must be installed one at a time in most 486 class systems—and two at a time in Pentium class systems.
Dual inline memory modules (DIMMs) are 64 bits wide, so they are installed normally one at a time in Pentium or newer systems.
Rambus inline memory modules (RIMM) are somewhat of an anomaly because they play by a different set of rules. They are typically only 16 or 32 bits wide. Depending on the module type and chipset, they are either used individually or in pairs.
Address Bus
The address bus is the set of wires that carries the addressing information used to describe the memory location to which the data is being sent or from which the data is being retrieved.
As with the data bus, each wire in an address bus carries a single bit of information. This single bit is a single digit in the address. The more wires
[email protected](digits) used in calculating these addresses, the greater the total number of address locations.
The size (or width) of the address bus indicates the maximum amount of RAM a chip can address.
For example, the 8086 and 8088 processors use a 20-bit address bus that calculates as a maximum of 220 or 1,048,576 bytes (1MB) of address locations.
Processor Memory-Addressing Capabilities
The data bus and address bus are independent, and chip designers can use whatever size they want for each. Usually, however, chips with larger data buses have larger address buses.
Internal Registers (Internal Data Bus) The size of the internal registers indicates how much information the
processor can operate on at one time and how it moves data around internally within the chip. This is sometimes also referred to as the internal data bus.
A register is a holding cell within the processor; for example, the processor can add numbers in two different registers, storing the result in a third register. The register size determines the size of data on which the processor can operate.
The register size also describes the type of software or commands and instructions a chip can run. That is, processors with 32-bit internal registers can run 32-bit instructions that are processing 32-bit chunks of data, but processors with 16-bit registers can’t.
[email protected] Most advanced processors today—chips from the 386 to the Pentium 4—
use 32-bit internal registers and can therefore run the same 32-bit operating systems and software.
The new Itanium and AMD processors have 64-bit internal registers, which require new operating systems and software to fully be utilized.
Internal registers often are larger than the data bus, which means the chip requires two cycles to fill a register before the register can be operated on.
For example, both the 386SX and 386DX have internal 32-bit registers, but the 386SX must “inhale” twice (figuratively) to fill them, whereas the 386DX can do the job in one “breath.”
The Pentium is an example of this type of design. All Pentiums have a 64-bit data bus and 32-bit registers.
But the Pentium is like two 32-bit chips in one. The 64-bit data bus provides for very efficient filling of these multiple registers. Multiple pipelines are called superscalar architecture, which was introduced with the Pentium processor.
Processor Speed Ratings A common misunderstanding about processors is their different speed
ratings. A computer system’s clock speed is measured as a frequency, usually
expressed as a number of cycles per second. A typical computer system runs millions of these cycles per second, so
speed is measured in megahertz. How can two processors that run at the same clock rate perform differently
with one running “faster” than the other? The answer is simple: efficiency. For example Pentium executes about twice as many instructions in a given
number of cycles as a 486. Therefore, given the same clock speed, a Pentium is twice as fast as a 486, and consequently a 133MHz 486 class processor is not even as fast as a 75MHz Pentium!
FSB The processor bus (also called the front-side bus or FSB) is the
communication pathway between the CPU and motherboard chipset, more specifically the North Bridge or Memory Controller Hub. This bus runs at the full motherboard/RAM speed—typically between 66MHz and 400MHz in modern systems, depending on the particular board and chipset design.
This same bus also transfers data between the CPU and an external (L2) memory cache on Pentium class systems.
The FSB speed is the speed at which the CPU talks to the RAM. Generally FSB speed should be equal to the RAM or motherboard speed. But in most Pentium 4 systems, FSB > RAM speed, unless you use RDRAM modules.
The internal speed is very much greater than the FSB speed, (3 to 6 times). Hence, virtually all modern processors since the 486DX2 run at some multiple of the motherboard speed.
[email protected] For example, a Pentium 4 2.53GHz chip runs at a multiple of 19/4 (4.75x)
times the motherboard speed of 533MHz. You can set the motherboard speed and multiplier setting via jumpers or
other configuration mechanism (such as BIOS setup) on the motherboard.
Bandwidth To determine the transfer rate for the processor bus, you multiply the data
width (64 bits for a Celeron/Pentium III/4 or Athlon/Duron) by the clock speed of the FSB.
For example, if you are using a Pentium III 1.13GHz that runs at a 133MHz motherboard speed, you have a maximum instantaneous transfer rate of roughly 1,066MB/sec. You get this result by using the following formula:
133.33MHz × 8 bytes (64 bits) = 1,066MB/sec
With Socket 423/478 (Pentium 4 – 400MHz FSB), you get
400MHz × 8 bytes (64 bits) = 3,200MB/secProcessor Socket and Slot Types
Intel and AMD have created a set of socket and slot designs for their processors. Each socket or slot is designed to support a different range of original and upgrade processors. The table below shows the specifications of these sockets.
Sockets 1, 2, 3, and 6 are 486 processor sockets. Sockets 4, 5, 7, and 8 are Pentium and Pentium Pro processor sockets. Pentium II processors are slot-1 type. But Pentium III processors are slot-1
as well as socket 370 type. Pentium 4 processors are of socket 423 and 478.
Processor Ranges Summary Pentium 75-266 MHz Pentium Pro 166 & 200 MHz Pentium II 233-450 MHz Pentium III 450-1400 MHz Pentium 4 1300-3800 MHz Itanium 733-1666 MHz Celeron 266-1700 MHz
Processor Features SMM (Power Management) - This circuitry enables processors to conserve
energy use and lengthen battery life. MMX Technology – multimedia (graphics & sound) enhancement SSE, SSE2, and SSE3 - includes 70 new instructions for graphics and
sound processing over what MMX provided. Dual Independent Bus Architecture (DIB) - Having two (dual)
independent data I/O buses enables the processor to access data from either of its buses simultaneously and in parallel, rather than in a singular sequential manner (as in a single-bus system).
Hyper-Threading Technology (HT) - allows a single processor to handle two independent sets of instructions at the same time.
Dual-core Technology - HT Technology is designed to simulate two processors in a single physical unit. A dual-core processor, as the name implies, contains two processor cores in a single processor package.
Socket & Slot Processors
Installing the Processor Most socket processors are inserted on the motherboard with ZIF (zero
insertion force) technique. Installing a slot processor is obvious.
[email protected] Processor speed ratings are configured on the motherboard by
Jumpers BIOS PnP
Processor Upgrades Intel designed in the capability to upgrade by designing standard sockets
that would take a variety of processors. Thus, if you have a motherboard with Socket 3, you can put virtually any 486 processor in it; if you have a Socket 7 motherboard, it should be capable of accepting virtually any Pentium processor (or Socket 7-based third-party processor).
To maximize your motherboard, you can almost always upgrade to the fastest processor your particular board will support. Because of the varieties of processor sockets and slots—not to mention voltages, speeds, and other potential areas of incompatibility—you should consult with your motherboard manufacturer to see whether a higher-speed processor will work in your board.
For example, if your motherboard uses Socket 370, you might be able to upgrade to the fastest 1.4GHz version of the Pentium III. Before purchasing a new CPU, you should verify that the motherboard has proper bus speed, voltage settings, and ROM BIOS support for the new chip.
Upgrading the processor can, in some cases, double the performance of a system. However, if you already have the fastest processor that will fit a particular socket, you need to consider other alternatives. In that case, you really should look into a complete motherboard change, which would let you upgrade to a newer CPU at the same time.
Things to match with the MB
The following processor parameters should lie in the range of the motherboard’s specification when upgrading.
Socket / Slot Type Internal Clock Speed External Clock Speed (FSB) L2 Cache Memory
Processor Troubleshooting Techniques
[email protected] Processors are normally very reliable. Most PC problems are with other
devices, but if you suspect the processor, there are some steps you can take to troubleshoot it.
The easiest thing to do is to replace the microprocessor with a known-good spare. If the problem goes away, the original processor is defective. If the problem persists, the problem is likely elsewhere.
If during the POST the processor is not identified correctly, your motherboard settings might be incorrect or your BIOS might need to be updated. Check that the motherboard is jumpered or configured correctly for your processor, and make sure you have the latest BIOS for your motherboard.
If the system seems to run erratically after it warms up, try setting the processor to a lower speed setting. If the problem goes away, the processor might be defective or over clocked.
Many hardware problems are really software problems in disguise. Be sure you have the latest BIOS for your motherboard, as well as the latest drivers for all your peripherals.
Chapter Nine
[email protected] Interface
Overview The interface used to connect a hard disk drive to a modern PC is typically
called IDE (Integrated Drive Electronics). An interesting fact is that the true name of the interface is ATA (AT
Attachment). Integrated Drive Electronics refers to the fact that the interface electronics or
controller is built into the drive and is not a separate board, as with earlier drive interfaces.
Today, ATA is used to connect not only hard disks, but also CD and DVD drives, high-capacity Super Disk floppy drives, and tape drives.
PATA vs SATA
ATA is a 16-bit parallel interface, meaning that 16 bits are transmitted simultaneously down the interface cable.
A new interface called Serial ATA was officially introduced in late 2000 and is being adopted in systems starting in 2002.
Serial ATA (SATA) sends 1 bit down the cable at a time, enabling thinner and smaller cables to be used and providing higher performance due to the higher cycling speeds allowed.
The primary advantage of ATA drives over the older, separate controller-based interfaces and newer host bus interface alternatives, such as SCSI and IEEE-1394 (iLink or FireWire), is cost.
The ATA connector on motherboards in many systems is a 40-pin connector.
IDE Bus Versions
ATA interface is integrated within the motherboard chipset South Bridge or I/O Controller Hub chip.
There have been four main types of IDE interfaces based on three bus standards:
■ Serial AT Attachment (SATA)■ Parallel AT Attachment (ATA) IDE (based on 16-bit ISA)■ XT IDE (based on 8-bit ISA, obsolete)■ MCA IDE (based on 16-bit Micro Channel, obsolete)
In a parallel ATA drive configuration, you are still getting only 16-bit transfers between the drive and the motherboard-based host interface. Even so, the clock speeds of the ATA interface are high enough that one or two hard drives normally can’t supply the controller enough data to saturate even a 16-bit channel.
[email protected] Standards
The parallel ATA interface has evolved into several successive standard versions, introduced as follows:■ ATA-1 (1986–1994)■ ATA-2 (1995; also called Fast-ATA, Fast-ATA-2, or EIDE)■ ATA-3 (1996)■ ATA-4 (1997; also called Ultra-ATA/33)■ ATA-5 (1998–present; also called Ultra-ATA/66)■ ATA-6 (2000–present; also called Ultra-ATA/100)■ ATA-7 (2001–present; also called Ultra-ATA/133)
Each version of ATA is backward-compatible with the previous versions.
[email protected] I/O Cable
A 40-conductor ribbon cable is specified to carry signals between the bus adapter circuits and the drive (controller).
To maximize signal integrity and eliminate potential timing and noise problems, the cable should not be longer than 18'' (0.46 meters).
If the cable is too long, you can experience data corruption and other errors that can be maddening.
Two primary variations of IDE cables are used today: one with 40 conductors and the other with 80 conductors. Both use 40-pin connectors, and the additional wires in the 80-conductor version are simply wired to ground. The additional conductors are designed to reduce noise and interference and are required when setting the interface to run at 66MB/sec (ATA/66) or faster.
The drive and host adapter are designed to disable the higher-speed ATA/66, ATA/100, or ATA/133 modes if an 80-conductor cable is not detected.
The 80-conductor cable can also be used at lower speeds; although this is unnecessary, it improves the signal integrity. Therefore, it is the recommended version no matter which drive you use.
Dual-Drive Configurations Dual-drive ATA installations can be problematic because each drive has its
own controller and both controllers must function while being connected to the same bus.
The primary drive (drive 0) is called the master, and the secondary drive (drive 1) is called the slave. You designate a drive as being master or slave by setting a jumper or switch on the drive.
Setting the jumper to master or slave enables discrimination between the two controllers by setting a special bit (the DRV bit) in the Drive/Head Register of a command block.
Most IDE drives can be configured with four possible settings:■ Master (single-drive)■ Master (dual-drive)■ Slave (dual-drive)■ Cable select
Serial ATA
Sending data at rates faster than 133MBps down a parallel ribbon cable is fraught with all kinds of problems because of signal timing, electromagnetic interference (EMI), and other integrity problems.
The solution is called Serial ATA, which is an evolutionary replacement for the venerable parallel ATA physical storage interface.
Serial ATA is software-compatible with parallel ATA. Serial ATA uses much smaller and thinner cables with only seven
conductors that are easier to route inside the PC and easier to plug in with smaller, redesigned cable connectors.
Small Computer System Interface
The Small Computer System Interface (SCSI, often referred to as “scuzzy”) standard, like the IDE concept, provides a true systemlevel interface for the drive.
The SCSI interface can be used to connect diverse types of peripherals to the system. As an example, a SCSI chain could connect a controller to a hard drive, a CD-ROM drive, a high-speed tape drive, a scanner, and a printer.
Additional SCSI devices are added to the system by daisy-chaining them together, i.e the input of the second device is attached to the SCSI output of the first device, and so forth.
SCSI Cables and Connectors In PC-compatible systems, the SCSI interface uses a 50-pin signal cable
arrangement. The 50-pin SCSI connections are referred to as A-cables.
SCSI Addressing
The SCSI specification permits up to eight SCSI devices to be connected together. The SCSI port can be daisy-chained to allow up to six external peripherals to be connected to the system.
To connect multiple SCSI devices to a SCSI host, all the devices, except the last one, must have two SCSI connectors: one for SCSI-In, and one for SCSI-Out.
Each SCSI device in a chain must have a unique ID number assigned to it. Even though there are a total of eight possible SCSI ID numbers for each controller, only six are available for use with external devices.
Most SCSI controller cards are set to SCSI-7 by default from their manufacturers.
With older SCSI devices, address settings were established through jumpers on the host adapter card.
Each device had a SCSI number selection switch, or a set of configuration jumpers for establishing its ID number.
SCSI Termination The SCSI daisy chain must be terminated with a resistor network pack at
both ends. Single-connector SCSI devices are normally terminated internally. If not, a
SCSI terminator cable (containing a built-in resistor pack) must be installed at the end of the chain.
SCSI termination is a major cause of SCSI-related problems. Poor terminations cause a variety of different system problems, including the following:
Failed system startupsHard drive crashesRandom system failures
Chapter TenHard-Disk Storage
Definition of a Hard Disk A hard disk drive is a sealed unit that a PC uses for nonvolatile data storage. Nonvolatile, or semi-permanent, storage means that the storage device
retains the data even when no power is supplied to the computer. A hard disk drive contains rigid, disk-shaped platters, usually constructed of
aluminum or glass. Unlike floppy disks, the platters can’t bend or flex—hence the term hard
disk.
Basic components of a Hard Disk A hard disk is comprised of four basic parts:
platters, a spindle, read/write heads, and integrated electronics.
Platters are rigid disks made of metal or plastic. Both sides of each platter are covered with a thin layer of iron oxide or other magnetizable material.
The platters are mounted on a central axle or spindle, which rotates all the platters at the same speed.
Read/write heads are mounted on arms that extend over both top and bottom surfaces of each disk. There is at least one read/write head for each side of each platter. The arms jointly move back and forth between the platters’ centers and outside edges; this movement, along with the platters’ rotation, allow the read/write heads to access all areas of the platters.
The integrated electronics translate commands from the computer and move the read/write heads to specific areas of the platters, thus reading and/or writing the needed data.
Hard Disk Drive Operation Hard disk drives usually have multiple disks, called platters, that are stacked
on top of each other and spin in unison, each with two sides on which the drive stores data.
The heads read and write data in concentric rings called tracks, which are divided into segments called sectors, which typically store 512 bytes each.
Most standard-issue drives found in PCs today spin at 5,400rpm, with high performance models spinning at 7,200rpm. The 10,000rpm or 15,000rpm drives are usually found only in very high-performance workstations or servers.
The heads in most hard disk drives do not (and should not!) touch the platters during normal operation.
However, on most drives, the heads do rest on the platters when the drive is powered off. In most drives, when the drive is powered off, the heads move to the innermost cylinder, where they land on the platter surface.
Head crash When the drive is powered on, the heads slide on the platter surface as they
spin up, until a very thin cushion of air builds up between the heads and platter surface, causing the heads to lift off and remain suspended a short distance above or below the platter.
If the air cushion is disturbed by a particle of dust or a shock, the head can come into contact with the platter while it is spinning at full speed.
When contact with the spinning platters is forceful enough to do damage, the event is called a head crash.
[email protected] The result of a head crash can be anything from a few lost bytes of data to a
completely ruined drive. Every hard disk ever made eventually fails. Hard disks are fragile, and comparatively speaking, they are certainly one of
the more fragile components in your PC.
How Is Data Stored and Retrieved?
Computers record data on hard disks as a series of binary bits. Each bit is stored as a magnetic charge (positive or negative) on the oxide coating of a disk platter.
When the computer requests data stored on the disk, the platters rotate and the read/write heads move back and forth to the specified data areas. The read/write heads read the data by determining the magnetic field of each bit, positive or negative, and then relay that information back to the computer.
The read/write heads can access any area of the platters at any time, allowing data to be accessed randomly (rather than sequentially, as with a magnetic tape).
Preparing a hard disk drive Consequently preparing a hard disk drive, for data storage involves three
steps:1. Low-level formatting (LLF)2. Partitioning3. High-level formatting (HLF)
The most basic form of disk organization is called formatting. Formatting prepares the hard disk so that files can be written to the platters and then quickly retrieved when needed.
Hard disks must be formatted in two ways: physically (low level) and logically (high level).
Physical Formatting
A hard disk must be physically formatted before it can be logically formatted. A hard disk’s physical formatting (also called low-level formatting) is usually performed by the manufacturer.
Physical formatting divides the hard disk’s platters into their basic physical elements:
tracks, sectors, and cylinders.
These elements define the way in which data is physically recorded on and read from the disk.
Tracks, Sectors and Cylinder
Tracks are concentric circular paths written on each side of a platter, like those on a record or compact disc. The tracks are identified by number, starting with track zero at the outer edge.
Tracks are divided into smaller areas or sectors, which are used to store a fixed amount of data. Sectors are usually formatted to contain 512 bytes of data (there are 8 bits in a byte).
A cylinder is comprised of a set of tracks that lie at the same distance from the spindle on all sides of all the platters. For example, track three on every side of every platter is located at the same distance from the spindle. If you imagine these tracks vertically connected, the set forms the shape of a cylinder.
Cylinders
Computer hardware and software frequently work using cylinders. When data is written to a disk in cylinders, it can be fully accessed without
having to move the read/write heads. Because head movement is slow compared to disk rotation and switching between heads, cylinders greatly reduce data access time.
Bad Sectors
After a hard disk is physically formatted, the magnetic properties of the platter coating may gradually deteriorate. Consequently, it becomes more and more difficult for the read/write heads to read data from or write data to the affected platter sectors. The sectors that can no longer be used to hold data are called bad sectors.
Fortunately, the quality modern disks is such that bad sectors are rare. Furthermore, most modern computers can determine when a sector is bad; if this happens, the computer simply marks the sector as bad (so it will never be used) and then uses an alternate sector.
Partitioning
After a disk has been physically formatted, it can be divided into separate physical sections or partitions. Each partition functions as an individual unit, and can be logically formatted with any desired file system.
Why Use Multiple Partitions? Install more than one OS on your hard disk; Make the most efficient use of your available disk space; Make your files as secure as possible; Physically separate data so that it is easy to find files and back up
data.Partition Types
There are three kinds of partitions: primary, extended, and logical.
Primary and extended partitions are the main disk divisions; one hard disk may contain up to four primary partitions, or three primary partitions and one extended partition. The extended partition can then be further divided into any number of logical partitions.
A primary partition usually contains an operating system along with any number of data files (for example, program files or user files).
An extended partition is essentially a container in which you can further physically divide your disk space by creating an unlimited number of logical partitions.
An extended partition does not directly hold data. You must create logical partitions within the extended partition in order to store data.
Logical partitions can exist only within an extended partition and are meant to contain only data files and OSs that can be booted from a logical partition (OS/2, Linux, and Windows NT).
Logical Formatting (HLF) After a hard disk has been partitioned, it must be logically formatted. Logical formatting places a file system on the disk, allowing an operating
system (such as DOS, OS/2, Windows, or Linux) to use the available disk space to store and retrieve files.
Different OSs (operating systems) use different file systems, so the type of logical formatting you apply depends on the OS you plan to install.
High-level formatting is not really a physical formatting of the drive, but rather the creation of a table of contents for the disk.
The DOS FORMAT command can perform both low-level and high-level format operations on a floppy disk, but it performs only the high-level format for a hard disk.
Each partition can be formatted with a different file system, allowing you to install multiple OSs.
File Systems A file system performs three main functions:
1) tracking allocated and free space, 2) maintaining directories and file names, and 3) tracking where each file is physically stored on the disk.
Different file systems are used by different operating systems. Some OSs can recognize only one file system, while other OSs can recognize several. Some of the most common file systems are the following:
• FAT (File Allocation Table)• FAT32 (File Allocation Table 32)• NTFS (New Technology File System)• HPFS (High Performance File System)• NetWare File System• Linux Ext2 and Linux Swap
[email protected] Disk Features
To make the best decision in purchasing a hard disk for your system or to understand what distinguishes one brand of hard disk from another, you must consider many features.
■ Capacity■ Performance
Transfer rate Average access time
■ Reliability■ Cost
Physical Installation
The step-by-step procedures for installing a hard drive are as follows:1. Check your computer for an unused ATA/IDE connector. Typical Pentium-
class and newer PCs have two ATA/IDE connectors, allowing for up to four ATA/IDE devices.
2. Double-check the pin configuration and cable type. The colored (normally red or red-flecked) stripe on one edge of the cable goes to pin 1 of the hard drive’s data connector. Most cables and drive connectors are keyed to prevent improper (backward) installation, but many are not.
3. Configure the drive jumpers. If the drive is ATA/IDE and you are using a cable that supports CS, you must set the CS jumper on any drives connected to that cable. Otherwise, you must set the drives on the cable as either master or slave.
4. Attach the data cable connector to the back of the drive and the appropriate power connector to the drive. Most hard drives use the larger, or “Molex,” four-wire power connector.
5. Turn on the computer and listen for the new hard disk to spin up. Restart the computer and access the BIOS setup screens to configure the new hard disk.
Chapter ElevenOptical Storage
Overview
There are basically two types of disk storage for computers: magnetic and optical. Magnetic storage is represented by the standard floppy and hard disks installed in most PC systems, where the data is recorded magnetically on rotating disks.
Optical disc storage is similar to magnetic disk storage in basic operation, but it reads and records using light (optically) instead of magnetism.
Although most magnetic disk storage is fully read- and write-capable many times over, many optical storage media are either read-only or write-once.
Optical storage has proven to be much slower and far less dense than magnetic storage and is much more adaptable to removable-media designs.
What Is a CD-ROM? CD-ROM, or compact disc read-only memory, is an optical read-only storage
medium based on the original CD-DA (digital audio) format first developed for audio CDs. Other formats, such as CD-R (CD-recordable) and CD-RW (CD-rewritable), are expanding the compact disc’s capabilities by making it writable.
Additionally, new technologies such as DVD (digital versatile disc) are making it possible to store more data than ever on the same size disc.
CD-ROM discs are capable of holding up to 74 or 80 minutes of high-fidelity audio or up to 682MB (74-minute disc) or 737MB (80-minute disc) of data.
The term CD-ROM refers to both the discs themselves and the drive that reads them.
CD-ROM Technology A CD is made of a polycarbonate wafer, 120mm in diameter and 1.2mm
thick, with a 15mm hole in the center. This wafer base is stamped or molded with a single physical track in a spiral
configuration starting from the inside of the disc and spiraling outward. If you examined the spiral track under a microscope, you would see that
along the track are raised bumps, called pits, and flat areas between the pits, called lands.
The recorded data is read from the disc by scanning it with a lower power, continuous laser beam. The laser diode emits the highly focused, narrow beam that is reflected back from the disc. The reflected beam passes through a prism, and is bent 90 degrees, where it is picked up by the diode detector and converted into an electrical signal. Only the light reflected from a land on the disc is picked up by the detector. Light that strikes a pit is scattered and is not detected.
A CD-ROM drive
operates by using a laser to reflect light off the bottom of the disc. The reflected light is then read by a photo detector. The overall operation of a CD-ROM drive is as follows
1. The laser diode emits a low-energy infrared beam toward a reflecting mirror.2. The servo motor, on command from the microprocessor, positions the beam onto the correct track on the CD-ROM by moving the reflecting mirror.3. When the beam hits the disc, its refracted light is gathered and focused through the first lens beneath the platter, bounced off the mirror, and sent toward the beam splitter.4. The beam splitter directs the returning laser light toward another focusing lens.5. The last lens directs the light beam to a photo detector that converts the light into electric impulses.6. These incoming impulses are decoded by the microprocessor and sent along to the host computer as data.Encoding data on a CD-ROM
The disc spins
counter-clockwise, and slows down as the laser diode emitter/detector unit approaches the outside of the disc.
It begins spinning at approximately 500rpm at the inner edge of the disc, and slows down to about 200rpm at the outer edge of the disc.
Care for CDs
CD-ROM media should be handled with the same care as a photographic negative. The CD-ROM is an optical device and degrades as its optical surface becomes dirty or scratched.
Also it is important to note that, although discs are read from the bottom, the layer containing the track is actually much closer to the top of the disc because the protective lacquer overcoat is only 6–7 microns thick. Writing on the top surface of a disc with a ballpoint pen, for example, will easily damage the recording underneath.
Use only markers designed for writing on CDs. When cleaning a CD always move from the centre of the disc outwards,
never clean in rotational manner.
CD-ROM Drives
CD-ROM drives that operate at the speed of a conventional audio CD player are called single-speed (1×) drives. Advanced drives that spin twice, and three times as fast as the typical CD player are referred to as double-speed (2×) drives, triple-speed (3×) drives, and so forth.
Single-speed drives transfer data at a rate of 150KB per second. Double-speed drive transfers occur at 300KB per second, and so on. Most manufacturers are now focusing on 50× and 52× drives.
Exercise: Find the time required to read 400MB file from a CD-ROM at 40x.
Ans: 66.7 sec.DVD
DVD stands for digital versatile disc and in simplest terms is a high-capacity CD. In fact, every DVD-ROM drive is a CD-ROM drive; that is, they can read CDs as well as DVDs.
DVD uses the same optical technology as CD, with the main difference being higher density.
DVD discs can hold up to 4.7GB (single layer) or 8.5GB (dual layer) on a single side of the disc, which is more than 11.5 times greater than a CD. Double-sided DVD discs can hold up to twice that amount, although you currently must manually flip the disc over to read the other side.
The DVD disc’s pits and lands are much smaller and closer together than those on a CD, allowing the same physical-sized platter to hold much more information.
DVD Capacity (Sides and Layers)
Four main types of DVD discs are available, categorized by whether they are single- or double-sided, and single- or dual-layered. They are designated as follows:
DVD-5: 4.7GB Single-Side, Single-Layer. A DVD-5 is constructed from two substrates bonded together with adhesive.
DVD-9: 8.5GB Single-Side, Dual-Layer. A DVD-9 is constructed of two stamped substrates bonded together to form two recorded layers for one side of the disc, along with a blank substrate for the other side.
DVD-10: 9.4GB Double-Side, Single-Layer. A DVD-10 is constructed of two stamped substrates bonded together back to back. The disc must be removed and flipped to read the other side.
DVD-18: 17.1GB Double-Side, Dual-Layer. A DVD-18 combines both double layers and double sides.
Single-speed (1x) DVD-ROM drives provide a data transfer rate of 1.385MB/second, which means the data transfer rate from a DVD-ROM at 1x speed is roughly equivalent to a 9x CD-ROM.
Reading Capabilities of Optical Drives
Ordinary CD-ROM Drive
Multiread CD-ROM Drive
CD-RW Drive
DVD-ROM Drive
Combo Drive(CD-RW + D-ROM Drive)
DVD-RW Drive
Read CD-ROM Media YES YES YES YES YES YES
Read CD-RW NO YES YES YES YES YES
Record CD-R/RW NO NO YES NO YES YES
Read DVD-ROM NO NO NO YES YES YES
Record DVD-R/RW NO NO NO NO NO YES
Chapter TwelveFile Systems
FAT16 or FAT The FAT file system is characterized by the use of a file allocation table
(FAT) and clusters. The FAT is the heart of the file system; for safety, the FAT is duplicated to
protect its data from accidental deletion or corruption. Clusters are the FAT system’s smallest unit of data storage; one cluster
consists of a fixed number of disk sectors. The FAT records which clusters are used, which are unused, and where files
are located within the clusters. The FAT file system supports disk or partition sizes up to 2 GB, but only
allows a maximum of 65,525 (216) clusters. Therefore, whatever the size of the hard disk or partition, the number of sectors in one cluster must be large enough so that all available space can be included within 65,525 clusters.
The larger the available space, the larger the cluster size must be.
FAT32 FAT32 is a file system that can be used by Windows 95 OEM Service
Release 2 (version 4.00.950B), Windows 98, Windows Me, and Windows 2000.
However, DOS, Windows 3.x, Windows NT 3.51/4.0, earlier versions of Windows 95, and OS/2 do not recognize FAT32 and cannot boot from or use files on a FAT32 disk or partition.
The FAT32 file system uses smaller clusters than the FAT file system and has duplicate boot records.
Cluster sizes vary from 4KB to 32KB. Smaller cluster size means less hard-disk space wastage.
NTFS The NTFS (New Technology File System) is accessible only by Windows
NT/2000/XP/2003. NTFS is not recommended for use on disks less than 400 MB because it
uses a great deal of space for system structures. The central system structure of the NTFS file system is the MFT (Master File
Table). NTFS keeps multiple copies of the critical portion of the master file table to
protect against corruption and data loss. Like FAT and FAT32, NTFS uses clusters to store data files; however, the
size of the clusters is not dependent on the size of the disk or partition. A
[email protected] size as small as 512 bytes can be specified, regardless of whether a partition is 500 MB or 5 GB.
Cluster sizes vary from 512B to 4KB.
Using small clusters not only reduces the amount of wasted disk space, but also reduces file fragmentation, a condition where files are broken up over many noncontiguous clusters, resulting in slower file access.
Because of its ability to use small clusters, NTFS provides good performance on large drives.
Finally, the NTFS file system supports hot fixing, a process through which bad sectors are automatically detected and marked so that they will not be used.
Reading Capabilities
DOS Windows 95
Windows
NT 3.5
Windows 95 OSR2
Windows NT 4.0
Windows 98
Windows ME
Windows 2000
Windows XP
Windows 2003
FAT16 YESYES YES YES YES YES YES YES YES YES
FAT32 NO NO NO YES YES YES YES YES YES YES
NTFS NO NO YES NO YES NO NO YES YES YES
Conversions Windows can only convert partition file systems without destroying data in
one direction as shown below FAT16 à FAT32 à NTFS You cannot convert NTFS back to FAT32 or FAT32 back to FAT16!
Windows includes only basic tools for creating FAT32 partitions, but programs such as PartitionMagic from PowerQuest (www.powerquest.com) provide many other partition manipulation features.
These programs can easily convert partitions back and forth between FAT16, FAT32, and NTFS file systems, as well as resize, move, and copy partitions without destroying the data they contain.
They also allow changes in cluster sizes beyond what the standard Windows tools create.
Chapter ThirteenSystem Resources
Introduction System resources are the communications channels, addresses, and other
signals hardware devices use to communicate on the bus. They include
■ Memory addresses■ IRQ (interrupt request) channels■ DMA (direct memory access) channels■ I/O port addresses
These resources are required and used by many components of your system. Adapter cards need these resources to communicate with your system and accomplish their purposes. Not all adapter cards have the same resource requirements.
A serial communications port, for example, needs an IRQ channel and I/O port address, whereas a sound card needs these resources and at least one DMA channel.
Plug and Play (PnP) As your system increases in complexity, the chance for resource conflicts
increases.
Most adapter cards enable you to modify resource assignments by using the Plug and Play software that comes with the card.
Pnp enables devices to acquire these resources without the need for configuration.
Interrupts Interrupt request channels, or hardware interrupts, are used by various
hardware devices to signal the motherboard that a request must be fulfilled. This procedure is the same as a student raising his hand to indicate that he needs attention.
These interrupt channels are represented by wires on the motherboard and in the slot connectors.
When a particular interrupt is invoked, a special routine takes over the system, which first saves all the CPU register contents in a stack and then directs the system to the interrupt vector table.
Depending on which interrupt was invoked, the program corresponding to that channel is run.
[email protected] After the particular software routine finishes performing whatever function
the card needed, the interrupt-control software returns the stack contents to the CPU registers, and the system then resumes whatever it was doing before the interrupt occurred.
Through the use of interrupts, your system can respond to external events in a timely fashion.
Hardware interrupts are generally prioritized by their numbers; with some exceptions, the highest priority interrupts have the lowest numbers.
Higher-priority interrupts take precedence over lower priority interrupts by interrupting them.
IRQ Steering
If you overload the system—in this case, by running out of stack resources (too many interrupts were generated too quickly)—an internal stack overflow error occurs and your system halts.
The message Internal stack overflow - system halted usually appears as Internal stack overflow - system halted at a DOS prompt.
Each interrupt, is usually designated for a single hardware device. Most of the time, interrupts can’t be shared.
But the PCI bus inherently allows interrupt sharing; in fact, virtually all PCI cards are set to PCI interrupt A and share that interrupt on the PCI bus.
There are two sets of hardware interrupts in the system: PCI interrupts and ISA interrupts
The solution to the interrupt sharing problem for PCI cards was something called PCI IRQ Steering, which is supported in the more recent operating systems (starting with Windows 95 OSR 2.x) and BIOS.
Maskable interrupts
Because interrupts usually can’t be shared in an ISA bus system, you often run into conflicts and can even run out of interrupts when you are adding boards to a system.
If two boards use the same IRQ to signal the system, the resulting conflict prevents either board from operating properly.
Hardware interrupts are sometimes referred to as maskable interrupts, which means the interrupts can be masked or turned off for a short time while the CPU is used for other critical operations.
IRQ Conflicts Perhaps the most common IRQ conflict is the one between the integrated
COM2: port found in most modern motherboards and an internal (card-based) modem.
The solution to this problem is easy: Enter the system BIOS Setup and disable the built-in COM2: port in the system.
If a device listed in the table is not present, such as the motherboard mouse port (IRQ 12) or parallel port 2 (IRQ 5), you can consider those interrupts as available. For example, a second parallel port is a rarity, and most systems have a sound card installed and set for IRQ 5.
Also, on most systems IRQ 15 is assigned to a secondary IDE controller. If you do not have a second IDE hard or optical drive, you could disable the secondary IDE controller to free up that IRQ for another device.
Note that an easy way to check your interrupt settings is to use the Device Manager in Windows 95/98, Windows NT, or Windows 2000/XP.
DMA Channels Direct Memory Access (DMA) channels are used by communications
devices that must send and receive information at high speeds.
A serial or parallel port does not use a DMA channel, but a sound card or SCSI adapter often does.
DMA channels sometimes can be shared if the devices are not the type that would need them simultaneously.
For example, you can have a network adapter and a tape backup adapter sharing DMA channel 1, but you can’t back up while the network is running.
8-Bit ISA Bus DMA Channels
In the 8-bit ISA bus, four DMA channels support high-speed data transfers between I/O devices and memory. Three of the channels are available to the expansion slots.
16-Bit ISA DMA Channels Since the introduction of the 286 CPU, the ISA bus has supported eight
DMA channels, with seven channels available to the expansion slots.
DMA Note that PCI adapters don’t use these ISA DMA channels; these are only
for ISA cards. However, some PCI cards emulate the use of these DMA channels (such as sound cards) to work with older software.
The only standard DMA channel used in all systems is DMA 2, which is universally used by the floppy controller.
DMA 4 is not usable and does not appear in the bus slots. DMA channels 1 and 5 are most commonly used by ISA sound cards, such as the Sound Blaster 16, or by newer PCI sound cards that emulate an older one for backwards compatibility.
I/O Port Addresses Your computer’s I/O ports enable communications between devices and
software in your system. They are equivalent to two-way radio channels.
If you want to talk to your serial port, you need to know on which I/O port (radio channel) it is listening. Similarly, if you want to receive data from the serial port, you need to listen on the same channel on which it is transmitting.
Unlike IRQs and DMA channels, our systems have an abundance of I/O ports. There are 65,535 ports — numbered from 0000h to FFFFh.
The biggest problem you have to worry about is setting two devices to use the same port.
Less Conflict
[email protected] Most modern plug-and-play systems resolve any port conflicts and select
alternative ports for one of the conflicting devices. One confusing issue is that I/O ports are designated by hexadecimal
addresses similar to memory addresses. They are not memory; they are ports.
Driver programs are primarily what interact with devices at the various port addresses. The driver must know which ports the device is using to work with it, and vice versa.
Motherboard and chipset devices usually are set to use I/O port addresses 0h–FFh, and all other devices use 100h–FFFFh.
To find out exactly which port addresses are being used on your motherboard, consult the board documentation or look up these settings in the Windows Device Manager.
Virtually all devices on the system buses use I/O port addresses. Most of these are fairly standardized, meaning conflicts or problems won’t often occur with these settings.
Resolving Resource Conflicts
The resources in a system are limited. Unfortunately, the demands on those resources seem to be unlimited.
As you add more and more adapter cards to your system, you will find that the potential for resource conflicts increases. If your system is fully PnP-compatible, potential conflicts should be resolved automatically, but often are not.
How do you know whether you have a resource conflict? Typically, one of the devices in your system stops working.
Symptoms Any of the following events could be diagnosed as a resource conflict:
■ A device transfers data inaccurately.■ Your system frequently locks up.■ Your sound card doesn’t sound quite right.■ Your mouse doesn’t work.■ Garbage appears on your video screen for no apparent reason.■ Your printer prints gibberish.■ You can’t format a floppy disk.■ The PC starts in Safe mode (Windows 9x).
Preventing One way to resolve conflicts is to help prevent them in the first place. Especially if you are building up a new system, you can take several steps to
avoid problems. One is to avoid using older ISA devices.
[email protected] Another way you can help is to install cards in a particular sequence, and
not all at once. If you have a setting for PnP Operating System in your BIOS, be sure it is
enabled if you are running an operating system with plug-and-play support, such as Windows 9x/Me/2000/XP. Otherwise, make sure it’s disabled if you are running an OS that is not plug-and-play, such as Windows NT.
Troubleshooting On initial startup start with a minimum configuration with only the graphics
card, memory, and hard-disk. This allows for the least possibility of system conflicts in the initial configuration.
After the basic system has been configured (and after you have successfully loaded your operating system and any updates or patches), you can then begin adding one device at a time in a specific order.
So, you will power down, install the new device, power up, and proceed to install any necessary drivers and configure the device.
Sequence Here’s the loading sequence for additional cards:
1. Sound card2. Internal or external modem3. Network card4. Auxiliary video devices, such as MPEG decoders 3D accelerators and so on5. SCSI adapter6. Anything else
Normally, using this controlled sequence of configuring or building up your system results in easier integration with less conflicts and configuration hassles.
Resolving Conflicts Manually In the past, the only way to resolve conflicts manually was to take the cover
off your system and start changing switches or jumper settings on the adapter cards.
Fortunately, this is a bit easier with plug-and-play because all the configuration is done via the Device Manager software included in the operating system.
Dig out the manuals for all your adapter boards; you might need them. Additionally, you could look for more current information online at the manufacturers’ Web sites.
Steps followed As you try various resource settings, keep the following questions in mind;
When did the conflict first become apparent?
[email protected] Are there two similar devices in your system that do not work? Have other people had the same problem, and if so, how did they
resolve it? Whenever you make changes in your system, reboot and see whether the
problem persists. When you believe that you have solved the problem, be sure to test all your
software.Plug-and-Play Systems
Plug and Play (PnP) represents a major revolution in recent interface technology.
Prior to PnP, PC users were forced to muddle through a nightmare of DIP switches and jumpers every time they wanted to add new devices to their systems.
For PnP to work, the following components are desired:■ PnP hardware■ PnP BIOS■ PnP operating system
Each of these components needs to be PnP-compatible.
The Hardware Component The hardware component refers to both computer systems and adapter
cards. PnP adapter cards communicate with the system BIOS and the operating
system to convey information about which system resources are necessary. The BIOS and operating system, in turn, resolve conflicts (wherever
possible) and inform the adapter card which specific resources it should use.The BIOS Component
The BIOS is responsible for identification, isolation, and possible configuration of PnP adapter cards.
The BIOS accomplishes these tasks by performing the following steps:1. Disables any configurable devices on the motherboard or on adapter
cards2. Identifies any PnP PCI or ISA devices3. Compiles an initial resource-allocation map for ports, IRQs, DMAs, and memory4. Enables I/O devices5. Scans the ROMs of ISA devices6. Configures initial program-load (IPL) devices, which are used later to boot the system7. Enables configurable devices by informing them which resources have been assigned to them8. Starts the bootstrap loader9. Transfers control to the operating system
[email protected] Operating System Component
The operating system component is found in most modern operating systems, such as Windows 9x/Me/2000/XP.
It is the responsibility of the operating system to inform users of conflicts that can’t be resolved by the BIOS.
Depending on the sophistication of the operating system, the user then could configure the offending cards manually (onscreen) or turn off the system and set switches on the physical cards.
When the system is restarted, the system is checked for remaining (or new) conflicts, any of which are brought to the user’s attention. Through this repetitive process, all system conflicts are resolved.
Part Two
Building or Upgrading Systems
System Components
In these days of commodity parts and component pricing, building your own system from scratch is no longer the daunting process it once was. Every component necessary to build a PC system is available off the shelf at competitive pricing. In many cases, the system you build can use the same or even better components than the top name-brand systems.
There are, however, some cautions to heed. The main thing to note is that you rarely save money when building your own system; purchasing a complete system from a mail-order vendor or mass merchandiser is almost always less expensive. The reason for this is simple: Most system vendors who build systems to order use many, if not all, of the same components you can use when building your own system. The difference is that they buy these components in quantity and receive a much larger discount than you can by purchasing only one of a particular item.
In addition, you pay only one shipping and handling charge when you
purchase a complete system instead of the multiple shipping charges you pay when you purchase separate components. In fact, the shipping and handling charges from ordering all the separate parts needed to build a PC through the mail often add up to $100 or more, and this doesn't count the additional time spent as well as additional telephone or Internet access charges accrued in the process. The cost rises if you encounter problems with any of the components and have to make additional calls or pay for shipping charges to send improper or malfunctioning parts back for replacement. Also, many companies charge restocking fees if you purchase something and then determine you don't need it or can't use it.
Finally, if you purchase parts locally, you typically must pay the additional state sales tax, as well as the higher prices usually associated with retail store sales.
Then there is the included software. Although I can sometimes come close in price to a commercial system when building my own from scratch, the bundled software really adds value to the commercial system. A copy of Windows XP costs $100 or more, and many commercial systems also include Microsoft Office or other applications as well.
If you do plan to upgrade your system after a year or so of use, you should avoid purchasing any extended warranties.
The components used in building a typical PC are as follows:
Case and power supply Motherboard
Processor with heat sink and fan
Memory
Floppy drive (optional)
Hard disk drive
Optical drive(s) (CD and/or DVD)
Keyboard and pointing device (mouse)
Video card and display
Sound card (optional) and speakers
[email protected] Modem (optional) or network interface card (optional)
Cables
Hardware (nuts, bolts, screws, and brackets)
Operating system software
Each of these components is discussed in the following sections. However, before you buy anything, you should keep in mind that support for audio, Ethernet, video, and so on is often built in to the motherboard.
Case and Power Supply
The case and power supply are typically sold as a unit, although some vendors do sell them separately even when sold together, you might want to replace the existing PSU with one of your choosing. There are a multitude of designs from which to choose, usually dependent on the motherboard form factor you want to use, the number of drive bays available, and whether the system is desktop or floor mounted. There are cases with extra fans for cooling (recommended), air filters on the air inlets to keep out the dust, removable side panels, or motherboard trays; cases that require no tools for assembly, rack-mounted versions, and more. For most custom-built systems, a mid-tower case supporting ATX form factor motherboards and ATX12V form factor power supplies is the recommended choice. The size and shape of a component is called the form factor. The most popular case form factors are as follows:
Full-tower Mid- or mini-tower
Desktop
Low-profile (also called Slim line)
Each specific case is designed to accept a specific motherboard and power supply form factor as well. You have to ensure that the particular case you choose will accept the type of motherboard and power supply you want to use.
When deciding which type of case to purchase, you should consider where you will place your computer. Will it be on a desk? Or is it more feasible to put the system on the floor
and just have the monitor, keyboard, and mouse on the desk? The amount of space you have available for the computer can affect other purchasing decisions, such as the length of the monitor, keyboard, and mouse cables.
After you have settled on a case form factor, you need to choose one that supports the motherboard and power supply form factors you want to use. The smaller mini-tower or slimline cases often accept only MicroATX, FlexATX, MicroBTX, or PicoBTX motherboards, which somewhat limit your choices. If the case you choose fits a full-size ATX board, you can be sure it also accepts the smaller MicroATX and FlexATX boards. The same is true for BTX: A chassis that can handle BTX also accepts MicroBTX and PicoBTX. FlexATX (and variations such as MiniITX) and PicoBTX motherboards are used in some of the latest small form factor systems.
Most mid-tower and larger cases accept full-size ATX boards, which have become the standard for most full-function systems. If you are interested in the most flexible type of case and power supply that will support the widest variety of future upgrades, I recommend getting a chassis that supports full-size ATX boards and ATX12V power supplies.
Important Considerations
Generally, any ATX case, motherboard, and power supply of sufficient wattage for your equipment can be put together to form the basis of a new system. However, there are two major exceptions you need to know about:
Many Dell systems built from 1996 through 2000 use nonstandard motherboards and power supplies with what appears to be a standard ATX power supply physical connector; however, the pin out and voltage levels have changed. If you mix a nonstandard Dell motherboard and a standard ATX power supply, or a standard ATX motherboard and a nonstandard Dell power supply, you will destroy the power supply and possibly your motherboard as well! If you want to upgrade newer Dell systems, you must either buy Dell-compatible power supplies for use with the Dell motherboard or replace both Dell components with standard ATX components.
Many of Dell's newer systems also use nonstandard power supplies and motherboards, but these are more obvious in that they do not use standard connectors either, which means a standard ATX motherboard or power supply will not physically plug in. This makes an upgrade difficult or impossible, but at least you won't blow up any hardware in the process.
Intel Pentium 4 (and newer) and AMD Athlon (and newer) CPUs require heavy heat sinks and fans for cooling. Be sure to use a heat sink designed
for your particular processor, and make sure it is properly installed. These high-powered systems also require an ATX12V power supply, which has an additional 12V connector for the motherboard-based CPU voltage regulators. ATX12V adapters are available to convert standard ATX power supplies, but in general you should upgrade to an ATX12V supply that has upgraded internal circuitry and wiring to handle the additional 12V power required.
Whether you choose a desktop or one of the tower cases is really a matter of personal preference and system location. Most people feel that the tower systems are roomier and easier to work on, and the full-sized tower cases have a lot of bays for various storage devices. Tower cases typically have enough bays to hold floppy drives, multiple hard disk drives, optical drives, tape drives, and anything else you might want to install. However, some of the desktop cases can have as much room as the towers, particularly the mini- or mid-tower models. In fact, a tower case is sometimes considered a desktop case turned sideways or vice versa. Some cases are convertible that is, they can be used in either a desktop or tower orientation.
Tip
Mini-tower systems are an exception to the roomy tower case rule. These systems normally use the MicroATX, FlexATX, MicroBTX, or PicoBTX motherboards and might have only two or three drive bays. These systems are compact and somewhat difficult to work on. These systems are, however, easily picked up and moved from one location to another.
When it comes to the power supply, the most important consideration is how many devices you plan to install in the system and how much power they require
When you build your own system, you should always keep upgradeability and reparability in mind. A properly designed custom PC should last you far longer than an off-the-shelf model because you can more easily add or replace components. When choosing a case and power supply, leave yourself some room for expansion, on the assumption that you will eventually want to install an additional hard drive or some other new device that appears on the market that you can't live without.
Processor
Both Intel and AMD sell processors through two primary channels or methods. They are referred to as boxed (or retail) and OEM.
The motherboards you consider should have one of the following processor sockets or slots:
Socket 775. Supports the third-generation Intel Pentium 4 processors, including the newer Pentium 4 EE (Extreme Edition), Pentium D, and Pentium 4 E
Socket 939. Supports the second-generation Athlon 64 FX processors, including the newer Athlon 64 X2
Socket 940. Supports the original Athlon 64 FX processors
Socket 754. Supports the Athlon 64 processors
The following socket types also can be purchased but are not compatible with the latest CPU models and will limit your future processor upgrade options:
Socket 478. Supports the second- and third-generation Intel Pentium 4 and compatible Celeron processors
Socket A (462). Supports the AMD Athlon, Athlon XP, and Duron processors
Socket 370 (also called PGA370). Supports the PGA versions of the Intel Pentium III and compatible Celeron processors
Because the motherboard you choose dictates or limits your choice in processor, you should choose your processor first, which will then dictate the type of CPU socket (or slot) that must be present. For more information on processors, refer to Chapter 3, "Microprocessor Types and Specifications."
See "Processor Socket and Slot Types," p. 87.
Depending on the type of motherboard you select, there might be jumpers on the motherboard to set for processor type and speed. It also might have jumpers to control the voltage supplied to the processor. Typically, older Socket 7 or Super7 boards have jumpers for motherboard bus speed, CPU multiplier, and CPU voltage settings. If you purchase this type of board, be sure you get these settings correct; otherwise, the system won't run properly. In a worst-case situation, you can damage the processor with too high a voltage setting, for example.
All modern processor sockets handle these settings automatically, so there is little danger of incorrect settings. Even so, several boards have overrides for the automatic settings,
which can be useful for those intending to hotrod or overclock their processors. Most of these boards use the BIOS Setup to control these overrides, so no jumpers or switches need to be set.
Tip
A useful cross-reference of all modern Pentium and Athlon CPUs can be found at the Tom's Hardware website: www.tomshardware.com. The charts change fairly often, so you should search within the CPU section of the site.
Motherboard
Several compatible form factors are used for motherboards. The form factor refers to the physical dimensions and size of the board and dictates into which type of case the board will fit. The types of compatible industry-standard motherboard form factors generally available for system builders are as follows:
Modern form factors
BTX ATX
MicroATX
FlexATX
NLX
MiniITX (semiproprietary)
All others
Proprietary designs (some Compaq, Dell Optiplex, Hewlett-Packard, notebook/portable systems, and so on); many Dell Dimension systems from 1996 through 2000 use ATX form factors, but with different electrical pinouts; newer Dell Dimension and Dimension XPS systems use proprietary motherboards and power supplies as well.
BTX is the latest form factor, designed as an improved replacement for ATX; however, BTX is not physically compatible with and requires a different chassis from ATX. Because BTX was designed in part to help reduce the effects of hotter and hotter-running processors by better controlling airflow through the chassis, the recent trend in CPU design of increasing performance through design efficiency rather than ramp-ups in pure clock speed has diminished the need for it. Consequently, ATX has remained the
dominant form factor for PCs and is likely to remain so for some time.
Note
For more information on all the motherboard form factors, refer to Chapter 4, "Motherboards and Buses." You can also find the reference standard documents detailing the modern form factors at the Desktop Form Factors website: http://www.formfactors.org.
In addition to processor support and form factor, you should consider several other features when selecting a motherboard. The following sections examine each feature.
Chipsets
Aside from the processor, the main component on a motherboard is called the chipset. This usually is a set of one to five chips that contains the main motherboard circuits. These chipsets replace the 150 or more distinct components that were used in the original IBM AT systems and enable a motherboard designer to easily create a functional system from just a few parts. The chipset contains all the motherboard circuitry except the processor and memory in most systems.
Because the chipset really is the motherboard, the chipset used in a given motherboard has a profound effect on the performance of the board. It dictates all the performance parameters and limitations of the board, such as memory size and speed, processor types and speeds, supported buses and their speeds, and more. If you plan to incorporate technologies such as the Accelerated Graphics Port (AGP) or the Universal Serial Bus (USB) into your system, you must ensure that your motherboard has a chipset that supports these features.
Because chipsets are constantly being introduced and improved over time, I can't list all of them and their functions here; however, you will find a detailed description of many of them in Chapter 4. Several popular high-performance chipsets are on the market today.
See "Chipsets," p. 253.
See "Motherboard Selection Criteria (Knowing What to Look For)," p. 405.
Clearly, the selection of a chipset must be based largely on the processor you choose and the additional components you intend to install in the computer.
However, no matter which chipset you look for, I recommend checking the following supported features to ensure they match your needs and desires:
CPU bus speed support
[email protected] The type of main memory supported
AGP8X or PCI Express video support
Serial ATA interfaces (or both serial and parallel)
USB 2.0 (high-speed USB) support
Support for the fastest available processor in the processor family you choose, even if you are installing a slower model
If you are intent on building the ultimate PC (at least by this week's standards), you also should consider the faster processors available. Be sure not to waste your investment on the most capable processor by using a chipset that doesn't fully exploit its capabilities.
When you are designing your system, carefully consider the number and type of expansion cards you intend to install. Then, ensure that the motherboard you select has the correct number of slots and that they are of the correct bus type for your peripherals (PCI, AGP, and PCI Express). Because most recent boards lack ISA slots, if you have any ISA peripherals, it is long past time that you replace them with more capable PCI or PCI Express versions.
When you buy a motherboard, I highly recommend you contact the chipset manufacturer and obtain the documentation (often called the data book) for your particular chipset. This explains how the memory and cache controllers, as well as many other devices in the system, operate. This documentation should also describe the Advanced Chipset Setup functions in your system's Setup program. With this information, you might be able to fine-tune the motherboard configuration by altering the chipset features. Because chipsets are frequently discontinued and replaced with newer models, don't wait too long to get the chipset documentation because most manufacturers make it available only for chips currently in production.
Note
One interesting fact about chipsets is that in the volume that the motherboard manufacturers purchase them, the chipsets usually cost about $40 each. If you have an older motherboard that needs repair, you usually can't purchase the chipsets because they aren't stocked by the manufacturer after they are discontinued. Not to mention that most chipsets feature surface mounting with ball grid array (BGA) packages that are extremely difficult to manually remove and replace. The lowcost chipset is one of the reasons motherboards have become disposable items that are rarely, if ever, repaired.
BIOS
Another important feature on the motherboard is the basic input/output system (BIOS). This is also called the ROM BIOS because the code is stored in a read-only memory (ROM) chip. There are several things to look for here. One is that the BIOS is supplied by one of the major BIOS manufacturers, such as AMI (American Megatrends International), Phoenix, or Award (owned by
Phoenix). Also, be sure that the BIOS is contained in a special type of reprogrammable chip called a Flash ROM or EEPROM (electrically erasable programmable read-only memory). This enables you to download BIOS updates from the manufacturer and, using a program it supplies, easily update the code in your BIOS. If you do not have the Flash ROM or EEPROM type, you must physically replace the chip if an update is required.
See "Upgrading the BIOS," p. 429.
Virtually all motherboards built in the last few years include a BIOS with support for the Plug and Play (PnP) specification. This makes installing new cards, especially PnP cards, much easier. PnP automates the installation and uses special software built in to the BIOS and the operating system (such as Windows 9x/Me and Windows 2000/XP) to automatically configure adapter cards and resolve adapter resource conflicts.
You also need to verify that the BIOS supports both the processor you plan to install initially and the processor you might upgrade to in the future. If the motherboard and chipset can handle a new processor but the BIOS cannot, a BIOS upgrade can be used to provide proper support.
Note
For more information on PnP, refer to "Plug and Play BIOS" in Chapter 5, "BIOS." Also, an exhaustive listing of PnP device IDs can be found in the Technical Reference section of the disc included with this book.
Memory
Older systems had L2 cache memory on the motherboard, but for almost all systems starting with the Pentium II, this cache is a part of the processor. The few remaining Socket 7 or Super7 motherboards do still include cache onboard, and it is normally soldered in and not removable or upgradeable.
See "Cache Memory: SRAM," p. 476.
Main memory typically is installed in the form of dual inline memory modules (DIMMs). Three physical types of main memory modules are commonly used in PC systems today, with several variations of each. The main types are as follows:
168-pin SDRAM DIMMs 184-pin DDR DIMMs
240-pin DDR2 DIMMs
The 168-pin SDRAM DIMMs are found only in older or lower-end systems today. DIMMs have become popular because they are 64 bits wide and can be used as a single bank on a Pentium or higher-class processor that has a 64-bit external data bus.
Double data rate (DDR) SDRAM memory is a newer variation on SDRAM in which data is transferred twice as quickly, and it is the most common type of memory used in recent systems. DDR2 DIMMs came out in new systems during 2004 and are fast becoming the most common type of memory in new systems.
Note
Memory modules using Rambus DRAM, which used proprietary Rambus memory modules called RIMMs, were used in a limited number of systems from 1999 through 2002 but have since been phased out. Although both DDR DIMMs and RDRAM RIMMs use 184-pin connectors, their pin configurations are completely different and the modules are not interchangeable.
See "DDR SDRAM," p. 486.
Current systems using a 64-bit CPU bus require a single DIMM (64 bits wide) to make a single bank. Systems using DDR or DDR2 DIMMs can also use dual-channel memory, in which pairs of matching DIMMs enable double the memory throughput.
Memory modules can include an extra bit for each 8 for parity checking or ECC use. If ECC is important to you, be sure your chipset (and motherboard) supports ECC before purchasing the more expensive ECC modules.
See "Parity and ECC," p. 514.
For more information on PC memory of all types, including added detail on RIMM and SIMM modules, refer to Chapter 6, "Memory."
I/O Ports
Virtually all motherboards today have built-in I/O ports. In rare cases where these ports are not built in, they must be supplied via a plug-in expansion board that, unfortunately, wastes an expansion slot. The following ports might be included in any new system you assemble:
PS/2 Keyboard connector (mini-DIN type)
[email protected] PS/2 Mouse port (mini-DIN type)
One or two serial ports
Parallel port
Four or more USB ports
Two or more FireWire ports
One or two analog VGA or DVI video connectors (integrated video)
RJ-45 port for 10/100 or 10/100/1000 Ethernet
Audio connectors (speakers, microphone, and so on)
Two or more serial ATA ports
Some motherboards lack the serial, parallel, keyboard, and mouse ports (referred to as legacy ports), instead relying on USB for those connections. You might want to avoid "legacy-free" motherboards if you still use peripherals with those types of connections. Most motherboards feature integrated sound, and many have optional integrated video as well.
All the integrated ports are supported either directly by the motherboard chipset or by an additional Super I/O chip and additional interface components. Adding the optional video and sound interfaces directly to the motherboard saves both money and the use of an expansion slot, especially important in the less expensive systems sold today. In the case of integrated video, however, you're likely to incur a performance hit as compared to having a separate AGP or PCI Express video card.
If these devices are not present on the motherboard, various Super I/O or multi-I/O boards that implement all these ports are available. Again, most of the newer versions of these boards use a single-chip implementation because it is cheaper and more reliable.
See "Super I/O Chips," p. 342.
The primary drawback of having functions such as video and networking built in to the motherboard, of course, is that you have little or no choice about the features or quality of the integrated adapters. Integrated components such as these are nearly always of serviceable quality, but they certainly do not push the performance envelope of higher-end expansion cards. Most people who decide to build a system themselves do so because they want optimum performance from every component, which you typically do not get from integrated video and sound.
Buying a motherboard with integrated adapters, however, does not preclude you from adding expansion devices of the same type. You usually can install a video or sound card into a system with an integrated sound or video adapter without major problems, except that the additional cost of the integrated component is wasted. You also might encounter difficulties with the automated hardware detection routines in operating systems such as Windows 9x/Me/2000/XP detecting the wrong adapter in your system, but you can remedy this by manually identifying the expansion card to the OS. If you want the convenience of integrated video but want to maintain the option of installing a faster PCI Express video card later, look for systems that provide both integrated video and the required slot you'll need for your video card.
See "Integrated Video/Motherboard Chipsets," p. 888; "Intel 845 Family," p. 286; and "Intel 865 Family," p. 288.
If four or more USB ports exist, they often are split among two or more buses, with one set of connections on the back of the board and another set as a pin-header connector on the motherboard. A cable then plugs in to this connector, enabling you to route the second USB bus port to the front of the PC case. Most newer cases have provisions for front-mounted USB ports in this manner, which makes temporarily connecting devices such as digital cameras or MP3 players for transferring files easier. Even though USB 2.0 support is increasingly common, some systems use a separate USB 2.0 support chip; therefore, some USB ports on such systems support only the older USB 1.1 standard. Also, you might need to enable USB 2.0 support in the system BIOS and load USB 2.0 drivers before USB 2.0 ports will support USB 2.0 devices at top speed.
Note that if your motherboard has integrated devices such as video and sound, you must go into the BIOS Setup to disable these devices if you want to add a card-based replacement device. Check your BIOS Setup menus for an Enable/Disable setting for any integrated devices.
Hard Disk Drives
Your system also needs at least one hard disk drive. In most cases, a drive with a minimum capacity of 80GB is recommended, although in some cases you can get away with less for a low-end configuration. High-end systems should have drives of 300GB or higher. One of the cardinal rules of computer shopping is that you can never have too much storage. Buy as much as you can afford, and you'll almost certainly end up filling it anyway.
Tip
If you are an Internet user, one informal method of estimating how much disk space you will need is to go by the speed of your Internet connection. If you have a high-speed link, such as that provided by a DSL connection, a cable modem, or a LAN, you will find that the ease of downloading large amounts of data fills disk drives amazingly quickly. I would
recommend at least a 120GB hard drive in these cases. In addition, a removable storage system with a large capacity, such as a dual-layer DVD+/-RW drive, is also a good idea.
Note that Windows 95 does not support any drives larger than 32GB. You should upgrade to at least Windows 98 or 2000, although at this point I recommend taking the leap to Windows XP or even Windows Vista after its release in late 2006.
For the time being, the most common hard drive interface for desktop systems is still parallel ATA, although serial ATA is becoming more popular and will likely be the only widely available choice in the next year or two.
Some of the newest motherboards now feature RAID-compatible ATA or SATA interfaces. These enable you to install two identical IDE drives (a pair of 80GB drives, for example) and treat them as a single very large and very fast 160GB hard drive.
Most new motherboards now feature Serial ATA (SATA) interfaces, many of which are also RAID compatible. Although the SATA drive interface is technically faster than the fastest ATA interface on the market (ATA-133), real-world SATA drive performance is currently on par with ATA drive performance because both are limited by the throughput of the drive mechanism and media. However, if your motherboard supports SATA, the smaller cable size used for data and the promise of higher performance in the future can still make using SATA drives a better choice.
Most systems have USB 2.0, and more and more systems have IEEE 1394 (FireWire) built in to the motherboard or added as PCI expansion cards. Although FireWire and USB 2.0based drives have performance similar to ATA drives and can be moved from system to system, they are not recommended as primary drives. However, they can be used for additional portable storage or system backup.
See "ATA RAID," p. 596, and "Serial ATA," p. 569.
Several brands of high-quality hard disk drives are available from which to choose, and most offer similar performance within their price and capacity categories. In fact, you might notice that the capacities and specifications of the various ATA and SATA drives certain manufacturers offer are remarkably similar. This is because a single drive assembly is manufactured for use with both interfaces.
Removable Storage
Despite diminishing usage, the floppy disk drive has remained a mainstay component of PCs for more than 20 years (counting both 5 1/4" and 3 1/2" floppy drives, of course). However, since the advent of the CD-RW, the floppy disk drive has largely been relegated to a minor role as an alternative system boot device. Many of today's systems are no
longer equipped with a 1.44MB 3 1/2" drive because all systems today are capable of booting from CD, thus making CD-R or CD-RW discs a useful high-capacity replacement for floppy or Zip drives.
However, for additional removable storage, I recommend a DVD+/-RW (DVD-rewriteable) drive over floppy, Zip, or even CD-RW, regardless of your budget. These are now relatively inexpensiveoften well under $100and they allow you to use your choice of optical media, be it CD or DVD. Rewritable DVD media prices have also dropped considerably in recent years, making the cost per megabyte of storage superior to using rewritable CD media. Rewritable CDs store just 700MB of data compared to 4.7GB for a single-layer DVD+/-RW disc. And if your DVD+/-RW drive of choice can also burn to dual-layer discs, that storage capacity is doubled. (Bear in mind, though, that dual-layer DVD media is considerably more expensive at this time.)
See "DVD," p. 738.
Regardless of format, some form of optical drive is considered a mandatory item in any PC you construct if for no other reason than because almost all software is now distributed on CD-ROM or DVD. That said, while the increasingly affordable rewritable DVD drive should be considered a required component in any new PC, an external hard drive is also worth considering if you need extra removable storage either for portability or for data backups. Even a dual-layer DVD cannot match the storage capacity of today's external hard drives, which can hold upwards of 400GB of data. Smaller 100GB drives that include USB 2.0 or FireWire ports (sometimes both) can now be had for around $100, and many of them include software that allows you to configure so-called "one-button backups" that let you simply press a button on the external drive and automatically back up your essential data.
On a smaller scale, USB-driven flash memory drives provide a much more compact storage solution that can be carried with you wherever you go. The first generation of flash drives often stored as little as 16MB of data, but today's larger devices can hold in excess of 1GB of data.
Input Devices
Obviously, your system needs a keyboard and some type of pointing device, such as a mouse. Different people prefer different types of keyboards, and the "feel" of one type can vary considerably from other types. If possible, I suggest you try a variety of keyboards until you find the type that suits you best. I prefer a stiff action with tactile feedback myself, but others prefer a lighter, quieter touch.
Keyboards and mice typically include connectors that can accommodate either PS/2 or USB ports. Even though PS/2 versions that plug in to a 6-pin mini-DIN (PS/2) connector have traditionally been the most popular, USB has all but supplanted them at this point on newer systems. Wireless keyboards and mice, such as Logitech's G7 laser mouse, often
have no support at all for the venerable PS/2 port.
Though rarely an issue in new systems, it's important to keep in mind that, with any USB device, you must have support in the operating system for USB, and in the case of USB keyboards and mice, your system BIOS must support a function called Legacy USB or USB Keyboard and Mouse if you want to use the USB keyboard or mouse outside the Windows graphical user interface. Virtually all recent BIOSs have this feature. However, to enable you to use your USB keyboard or mouse on both new and older systems, I recommend you look for models that also support the traditional PS/2 ports. This type usually ships with a USB-to-PS/2 adapter. These adapters can also be purchased separately if necessary.
If you prefer a wireless keyboard or mouse, it used to be important that you chose one that uses RF (radio) instead of IR (infrared) signaling and one that could use a single transceiver for both the keyboard and mouse. In current products, that choice is largely made for you. However, you should keep in mind that RF signaling might use either short-range proprietary frequencies or the industry-standard Bluetooth wireless network architecture. Bluetooth devices are preferable if you want to use the keyboard or mouse with a wide variety of devices or at distances greater than 6 feet or so from the system.
See "Keyboards," p. 1012.
See "Keyboard Technology," p. 1016.
Tip
You might be tempted to skimp on your keyboard and mouse to save a few dollars. Don't! You do all your interacting with your new PC through these devices, and cheap ones make their presence known every time you use your system. I insist on high-quality mechanical switchtype keyboards on all my systems.
The success of USB has changed the market so that there are virtually no limits to the types of devices available that can make use of the connection. Modems, keyboards, mice, optical drives, speakers, joysticks, hard drives, tape drives, floppy drives, scanners, cameras, MP3 players, and printers are just some of the devices available. However, before you start buying all USB peripherals for your new system, if your system supports only USB 1.1, you should be aware that performance problems can occur with some devices if used on a single bus, and sometimes compatibility problems can occur as well. USB 2.0 (also called High-Speed USB), which is standard for almost all new and recent motherboards, solves these problems.
See "USB Keyboards," p. 1027.
Video Card and Display
You need a video adapter and a monitor or display to complete your system. Numerous choices are available in this area, but the most important piece of advice I have to give is to choose a good monitor. The display is your main interface to the system and can be the cause of many hours of either pain or pleasure, depending on which monitor you choose. As has been the case for several years, the first choice you need to make in a display is whether to purchase a CRT or an LCD.
I usually recommend a minimum of a 19" CRT display these days (equivalent to a 17" LCD display). 17" CRTs are very usable as well, but anything smaller can't acceptably display a 1024x768 pixel resolution, which is really the minimum acceptable resolution for today's systems. If you opt for a 15" or smaller CRT display, you might find that the maximum tolerable resolution is 800x600. This might sound confusing because many 15" monitors are capable of displaying 1024x768 resolution or even higher, but the characters and features are so small onscreen at that resolution that excessive eyestrain and headaches are often the result; the display often is blurry when a monitor is run at its maximum resolution. If you spend a lot of time in front of your system and want to work in the higher screen resolutions, a 17" CRT display should be considered a mandatory minimum. However, because there is very little extra cost involved, I recommend a 19" CRT display; they work even better at the higher resolutions and have come down in price considerably from previous years. Look for CRT displays with lower dot pitch (0.28dpi or less), which indicates the size and spacing of dots in the CRT mask. Lower means higher resolution and a clearer picture.
If your desk space is limited or you don't mind paying more money per screen inch, consider the wide variety of flat-screen LCD panels now available (a 15" LCD panel is about equal in viewable area to a 17" CRT). In most cases they can be attached to a VGA analog port, but the most current models are designed to work with the DVI connector, which is rapidly becoming the default connector type on modern video cards. LCD panels are an excellent choice if you always use the native resolution (typically 1024x768 on 15" displays or 1280x1024 on 17" displays), but if you need to change resolutions (for previewing web page designs or game playing), CRTs are better.
Your video card and monitor should be compatible in terms of refresh rate. The minimum refresh rate for a solid, nonflickering CRT display is 70Hz72Hz (the higher, the better). If your new video card can display 32-bit color at a resolution of 1280x1024 and a refresh rate of 75Hz, but your monitor's maximum refresh rate at 1280x1024 is 60Hz, you can't use the video card to its maximum potential. Configuring a video adapter to deliver signals the monitor can't support is one of the few software configuration processes that can physically damage the system hardware. Pushing a monitor beyond its capabilities can cause it irreparable harm. Note that LCD displays don't flicker, regardless of the refresh rate.
In the past few years, video adapters had become standardized on the accelerated graphics port (AGP) interface. Today, however, many video cardsespecially high-performance cards have made the leap to PCI Express. In some cases you will find graphics
cards based on PCI as well. The only instance in which a PCI graphics card should be used in a desktop system is if you are adding a secondary video adapter for use with a second video display. Windows 98, Me, 2000, and XP support multiple monitors on a single system, and it's a feature that can be very useful for a variety of applications. If performance is your ultimate goal and you can tolerate the added expense, look for a system that supports dual PCI Express x16 graphics cards. Both NVIDIA and ATI offer high-performance video chipsets that can be used to run dual video cards together to increase video display performance.
See "Accelerated Graphics Port," p. 378.
See "3D Graphics Accelerators," p. 908.
If you are installing a newer video card as a replacement upgrade to your current system, you can remove the existing video card and replace it with any video card that supports the motherboard's standard (be it AGP or PCI Express). In the case of older systems using AGP, you should ensure that the AGP slot and card are compatible because AGP has been implemented in multiple versions based on speed (4x, 8x, and so on). You can also replace an existing PCI video card with another PCI video card if there is no AGP slot, but you should consider a system upgrade instead to provide an AGP or a PCI Express slot for faster video.
Many motherboards with onboard video also have an AGP or a PCI Express slot; if your motherboard has one, you can insert the applicable card into this slot. The onboard video should be automatically disabled in most cases, although you might have to disable it in the system BIOS instead.
Audio Hardware
All systems today should be capable of playing audio to some degree, which means you need at least a passable set of external speakers and either a motherboard with integrated audio or a separate sound card. Most systems today, even those without integrated video, now feature integrated audio, but it can be disabled if you prefer to add a dedicated high-quality sound card. Dedicated cards, such as Creative's X-Fi product line, are ideal if you want the best possible sound quality for DVD playback, audio capture and editing, or surround sound for gaming. Almost any motherboard-integrated audio system and sound card on the market today are compatible with the baseline Creative Sound Blaster series, Windows DirectSound, and other sound APIs. Virtually all dedicated sound cards are based on PCI, although you might be able to find older ISA cards if you look hard enough.
Caution
If you run older DOS-based games or applications, you need to keep in mind that today's audio chipsets (especially when used in a modern OS such as Windows XP) often fail to process audio. In some cases audio playback is spotty; in others it either fails entirely or causes the program itself not to run.
Speakers designed for use with PCs range from tiny, underpowered devices to large audiophile systems. Many of the top manufacturers of stereo speakers now produce speaker systems for PCs. Some include subwoofers or even a full Dolby 5.1, 6.1, or 7.1 surround sound implementation.
Accessories
Apart from the major components, you need several other accessories to complete your system. These are the small parts that can make the assembly process a pleasure or a chore. If you are purchasing your system components from mail-order sources, you should make a complete list of all the parts you need, right down to the last cable and screw, and be sure you have everything before you begin the assembly process. It is excruciating to have to wait several days with a half-assembled system for the delivery of a forgotten part.
Heat sinks/Cooling Fans
Most of today's faster processors produce a lot of heat, and this heat has to be dissipated so your system doesn't operate intermittently or even fail completely. Heat sinks are available in two main types: passive and active.
Passive heat sinks are simply finned chunks of metal (usually aluminum or copper) that are clipped or glued to the top of the processor. They act as a radiator and, in effect, give the processor more surface area to dissipate the heat. Active heat sinks, which include the heat sink itself and an attached fan, are required by most processors today because of their higher capacity and smaller space requirements. Often you have no control over which heat sink you use because it comes already attached to the processor. If you have to attach it yourself, you should use a thermal transfer grease or sticky tape to fill any air gaps between the heat sink and the processor. This allows for maximum heat transfer and the best efficiency.
Obviously, active heat sinks offer greater cooling capacity than the passive types. Boxed processors from Intel and AMD are sold with the heat sink and fan included. And although OEM processors don't include a heat sink from the processor manufacturer, most vendors who sell them add an aftermarket heat sink and fan to the package; often, aftermarket heat sinks and fans provide significantly better cooling than those shipped with boxed processors. Thus, an OEM processor is a better candidate for over clocking.
Caution
All modern heat sinks require that a thermal interface material (usually tape, grease, or paste) be applied to the base of the heat sink before installation.
Another consideration for cooling is with the case. The fan in the power supply and the one on the CPU heat sink are not enough for a modern high-performance system. I recommend you get a case that includes at least one additional cooling fan. This is typically mounted in the rear of the chassis, directing additional air out the back. Some cases include an extra fan in the front or side cover as well.
If you are upgrading an existing system, several companies make fan assemblies that insert into a drive bay for additional cooling. They take the place of a 5 1/4" drive and take air in through the front bezel, directing it back into the case. Bay-mounted fans are an especially good idea if you are using a 10,000rpm or faster hard drive because they run extremely hot (most hard drives still spin at 7,200rpm). There are even fan assemblies mounted on cards that blow air out the rear of the case. Keep in mind that it is best to keep the interior of the PC below 100°F; anything over 110° dramatically reduces component life and leads to stability problems.
Cables
PC systems need many different cables to hook up everything. These can include power cables or adapters, floppy drive cables, parallel and Serial ATA drive cables, and many others. Frequently, the motherboard includes the cables for any of the internal ports, such as floppy or hard drives. Other external devices you purchase come with included cables, but in some cases, they aren't supplied. The Vendor List on the disc included with this book contains contact information for several cable and small parts suppliers that can get you the cables or other parts you need to complete your system.
If you build your system using all OEM (what the industry calls white box) components, be aware that these sometimes don't include the accessories, such as cables, software, and additional documentation, that you would get with a boxed-retail version of the same component.
Hardware
You might need screws, standoffs, mounting rails (if your case requires them), and other miscellaneous hardware to assemble your system. Most of these parts are included with the case or your other system components. This is especially true of any card or disk drive brackets or screws. When you purchase a component such as a hard drive, some vendors offer you the option of purchasing the bare drive or a kit containing the required cables and mounting hardware for the device. Most of the time bare drives don't include any additional hardware, but you might not need it anyway if the mounting hardware comes with your case. Even so, spending the few additional dollars for the complete drive kit is rarely a waste of money. Even if you're left with some extra bits and pieces after
assembling your system, they will probably come in handy someday.
In situations in which you need other hardware not included with your system components, you can consult the Vendor List for suppliers of small parts and hardware necessary to get your system operational.
