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Using Information Technology
Chapter 4
Hardware--The CPU & Storage
Hardware--The CPU & Storage How to Buy a Multimedia Computer System
4.1 Microchips, Miniaturization, & Mobility
4.2 The System Unit
4.3 Secondary Storage
4.1 Microchips, Miniaturization, & Mobility
From Vacuum Tubes to Transistors to Microchips
Vacuum Tubes – 18,000 in ENIAC in 1946. Failed every 7 minutes, took 15 minutes to replace!
Transistor (1st was 1/100th size of vacuum tube) - a tiny electrically operated switch, or gate, that can alternate between “on” and “off” many millions of times per second
1960 – 1 transistor was ½ centimeter sq.
2003 – 3 million transistors on ½ cent sq.1940s vacuum tube towering
over 1950s transistor
4
CHIP or MICROCHIP
• A tiny piece of silicon (semiconductor) that contains millions of micro-miniature electronic components, mainly transistors. Silicon is found in sand.
• Microprocessor: Miniaturized circuitry of a computer processor – the part that processes, or manipulates data into information
Steps in Manufacture of a Microchip
1. Make large drawing. Reduce drawing hundreds of times to microscopic size.
2 Duplicate reduced photo many times on sheet.
3 Print sheet of multiple copies on a wafer made of silicon, a semiconductor.
4 Print layer after layer above and below original silicon surface.
5 Cut wafer into chips.
6 Mount chip in frame with connective pins extruding.
[Note: THEN transistors were individually formed. Circuits attached w/wire & solder. TODAY integrated circuits & wires are formed together in a single chip.
4.2 The System Unit
The Binary System: Using On/Off Electrical States to Represent Data & Instructions
The binary system has only two digits--0 and 1.
Bit - binary digit
Byte - group of 8 bits used to represent one character, digit, or other value
The Binary System: Using On/Off Electrical States to Represent Data & Instructions
Kilobyte 1000 bytes
Megabyte 1,000,000 bytes (one million)
Gigabyte 1,000,000,000 bytes (one billion)
Terabyte 1 trillion bytes
Petabyte 1 quadrillion bytes
The Binary System: Using On/Off Electrical States to Represent Data & Instructions
ASCII (American Standard Code for Information Interchange) - the binary code most widely used with microcomputers
EBCDIC (Extended Binary Coded Decimal Interchange Code) - used with large computers
Unicode - uses two bytes for each character rather than one. Instead of 256 character combinations of ASCII, 65,536 character combinations allow all languages to be represented.
The Computer Case: Bays, Buttons & Boards
Bay - a shelf or opening used for the installation of electronic equipment
System unit - houses the motherboard, power supply, and storage devices
Case - empty box with just power supply
Overhead view of system unit
The Motherboard & the Microprocessor Chip
Motherboard - the main circuit board in the system unit
Expansion - increasing a computer’s capabilities by adding hardware
Upgrading - changing to newer, more powerful versions
The Motherboard & the Microprocessor Chip
Two principal architectures or designs of microprocessors:
CISC (Complex Instruction Set Computing) - Supports a large number of instructions at relatively low processing speeds
RISC (Reduced Instruction Set Computing) - Supports a reduced number of instructions in order to obtain faster processing speeds
Two kinds of microprocessors used in most microcomputers today:
Intel-type chips for P/Cs made by Intel, AMD, and others (Pentium. The P4 has 42 million transistors)
Motorola-type chips made by Motorola for Apple Macintosh computers
The Motherboard & the Microprocessor Chip
MICROPROCESSOR – contains a system clock, which controls how fast all the operations within a computer takes place
System clock – uses fixed vibrations from a quartz crystal to deliver a steady stream of digital pulses or “ticks” to the CPU.
Ticks are called cycles
Faster clock speeds result in faster processing and execution of program instructions.
Steps in the machine cycle (Tick) [series of operations performed by control unit to execute a single programmed instruction]:
1. Fetch an instruction
2. Decode the instruction
3. Execute the instruction
4. Store the result Microprocessor speed expressed in Megahertz, a frequency equivalent to 1
million cycles (ticks) per second. (1 GHz - 1 billion cycles per second)
How Processor or CPU works: Control Unit, ALU, & Registers
CPU – Central processing unit (Brain): consists of 2 parts (both contain registers, high speed storage areas).
2 parts are linked by electronic roadways “bus.”
1. Control unit – deciphers each instruction stored in it and carries out. Directs electrical signals bet main memory & ALU & input/output devices.
2. Arithmetic Logic Unit – ALU – performs arithmetic & logic operations (comparisons) & controls speed
How Processor or CPU works: Control Unit, ALU, & Registers
Word size - # of bits a processor may process at one time. 32-bit “word” microprocessor will transfer data w/in each processor chip in 32-bit chunks.
BUS – bits are transmitted within the CPU and between CPU & other components of motherboard.
How Memory Works: RAM, ROM, CMOS, & Flash
Types of memory chips:
1. RAM - Random Access Memory, used to temporarily hold software instructions & data in main memory (volatile)
2. ROM
3. CMOS
4. Flash
4 types of RAM chips:1. DRAM – Dynamic RAM – must be constantly refreshed
2. SDRAM – Synchronous DRAM – Synchronized by system clock, goes faster
3. SRAM – Static RAM – doesn’t need to be refreshed, faster than DRAM
How Memory Works: RAM, ROM, CMOS, & Flash
Types of memory chips:
1. RAM
2. ROM - Read-Only Memory, which cannot be written on or erased by the computer user. Contains fixed start-up instructions
3. CMOS
4. Flash
How Memory Works: RAM, ROM, CMOS, & Flash
Types of memory chips:
1 RAM 2 ROM 3 CMOS - Complementary metal-oxide semiconductor;
powered by a battery and thus doesn’t lose its contents when the power is off (non volatile)
4 Flash
How Memory Works: RAM, ROM, CMOS, & Flash
Types of memory chips:
1 RAM 2 ROM 3 CMOS 4 Flash memory chips – to store program - can be erased and
reprogrammed more than once (non volatile)
How Cache Works: Level 1 (Internal) & Level 2 (External)
Cache - temporary storage for instructions and data that the processor is likely to use frequently, thus speeding up processing
Level 1 (L1) internal cache - built into the microprocessor (8-256 kilobytes – operates fast)
Level 2 (L2) external cache - consists of RAM chips outside microprocessor (64-2MB)
Virtual memory - current operating systems allow for use of free hard-disk space used to extend the capacity of RAM
Ports & Cables
Types of ports (connecting socket or jack on the outside of the system unit into which are plugged different kinds of cables):
1 Serial port - sends bits one at a time, one after another (keyboards, mouse, monitor, modem)
2 Parallel port3 SCSI port4 USB port5 Dedicated port6 Infrared port
Ports & Cables
1 Serial port 2 Parallel port -
transmits 8 bits simultaneously (fast data over short distances – 15 ft) (printers, external zip drive)
3 SCSI port4 USB port5 Dedicated port6 Infrared port
Ports & Cables
1 Serial port 2 Parallel port3 SCSI port - allows
fast data to be transmitted in a “daisy chain” to up to 7 devices
4 USB port5 Dedicated port6 Infrared port
Ports & Cables
1 Serial port 2 Parallel port3 SCSI port 4 USB Port (universal serial bus) - can
theoretically connect up to 127 peripheral devices daisy-chained to one general-purpose port (allows plug & play – so peripheral devices & expansions cards can be automatically configured while they are being installed.
5 Dedicated port6 Infrared port
Ports & Cables
1 Serial port 2 Parallel port3 SCSI port 4 USB5 Dedicated port -
special-purpose ports
6 Infrared port
Dedicated ports: mouse port, telephone jack, modem port, and
keyboard port
Ports & Cables
1 Serial port 2 Parallel port3 SCSI port 4 USB5 Dedicated port - special-
purpose ports6 Infrared port - allows a
computer to make a cableless connection with infrared-capable devices (handheld TV remote)
Expandability: Buses & Cards(Open vs. closed architecture)
Expansion slots- sockets on the motherboard into which you can plug expansion cards
Expansion cards - circuit boards that provide more memory or that control peripheral devices
Expandability: Buses & Cards
ISA bus (industry standard architecture) - for ordinary low-speed uses; the most widely used expansion bus
PCI bus (peripheral component interconnect)- for higher-speed uses; used to connect graphics cards, sound cards, modems, and high-speed network cards
AGP bus (accelerated graphics port) - for even higher speeds and 3D graphics
Note: system bus connects CPU to itself and to main memory
Expandability: Buses & Cards
Graphics cards - for monitors
Sound cards - for speakers and audio output
Modem cards - for remote communication via phone lines
Network interface cards - for remote communication via cable
PC cards - for laptop computers (formally PCMCIA cards)
4.3 Secondary Storage
Floppy disk
a removable flat piece of mylar plastic packaged in a 3.5-inch plastic case
Data & programs are stored on disks coating with magnetic spots following on/off patterns of data representation.
Tracks
sectors
DISK STORAGE
Floppy disk – 1.44 MB (400 typewritten pages)
Zip disks - 100 or 250 Mb
*SuperDisks - 120 Mb
*HiFD disks - 200 Mb
*Drive can also read floppy
Hard Disks
Hard disks - thin but rigid metal platters covered with a substance that allows data to be held in the form of magnetized spots
Read/write head does not touch disk; rides on air cushion
Hard Disks
Head crash - event that happens when the surface of the read/write head or particles on its surface come into contact with the surface of the hard-disk platter, causing the loss of some or all of the data on the disk
Hard DisksNonremovable hard disks - housed in a microcomputer system unit and used to store nearly all programs and most data files
See p. 164
Hard Disks
Removable hard disks - one or two platters enclosed along with read/write heads in a hard plastic case, which is inserted into a microcomputer’s cartridge drive
Bits on disk - dark stripes are 0 bits and bright stripes are
1 bits
Optical Disks: CDs & DVDs
Optical disk - a removable disk on which data is written and read through the use of laser beams
Optical Disks: CDs & DVDs
CD-ROM - read only. For pre-recorded text, graphics, and sound
CD-R - for recording on once
CD-RW - for rewriting many times
CD-Rom Drive’s speed denoted as data transfer by X which represents rate of 150 kilobytes per second. (44X = 44x150 kb)
Optical Disks: CDs & DVDs
DVD-ROM - for reading only [extremely high capacity (4.7-11.7 gigabytes)
DVD-R - for recording on once
For rewriting many times:
DVD-RWDVD-RAM DVD+RW
Magnetic Tape (up to 66 gigabytes)
Magnetic tape - thin plastic tape coated with a substance that can be magnetized (for 1s) or left non-magnetized (for 0s)
Tape cartridges - modules resembling audio cassettes that contain tape in rectangular, plastic housings
Smart Cards
Smart card (holds up to 250 pgs of data)
Looks like a credit card but contains a microprocessor embedded in the card (e.g., telephone debit card)
Optical card (holds up to 2000 pgs of data) Plastic, laser-recordable, wallet-type card used with an optical-card reader
[Note: conventional credit card strip holds ½ page of data]
Smart card in use
Flash Memory Cards
Flash memory card – circuitry on credit-card-size PC card that can be inserted into slots connecting to the motherboard
64 MB – projected up to 1 gigabyte
Concept Check
Which binary code is most often used with microcomputers?
ASCII (American Standard Code for Information Interchange)
Concept Check
How many bytes are in a terabyte?
One trillion
Concept Check
Which type of CD can be written to only once?
CD-R
Concept Check
Which binary code can represent all the characters of virtually every language in existence?
UNICODE
Concept Check
Which chip architecture provides faster processing speed--CISC or RISC?
RISC
Concept Check
Which measure of storage represents one billion bytes?
Gigabyte
Concept Check
What are the two parts of the CPU?
Control unit and arithmetic/logic unit (ALU)
Concept Check
What is the term for increasing a computer’s capabilities by adding hardware to perform tasks beyond the scope of the basic system?
Expansion
Concept Check
What is a gigahertz?
A measure of processing speed representing one billion cycles per second
Concept Check
What is the term for the special high-speed memory area on a chip that the CPU can access quickly?
Cache
Concept Check
What element are wafers composed of?
Silicon
Concept Check
What are the four steps of the machine cycle?
1. Fetch an instruction
2. Decode the instruction
3. Execute the instruction
4. Store the result