Unit II-Computer Hardware

Computer Hardware

UNIT II

OBJECTIVES:

At the end of the lecture the students will be able to:

1. Gain Basic knowledge of Computer Hardware2. Familiarize with the different computer input

and output devices3. Operate basic computer hardware4. Appreciate the advancement of the kinds of

computer

COMPUTER HARDWARE

Refers to the physical equipment of the computer system and other peripheral devices attached to the computer for input, output and storage purposes

HARDWARE COMPONENTS

1. Communication Devices Translate one form of communication from

an internal or external device into which the computer can understand, then sends it to an output device or to another computer

HARDWARE COMPONENTS

2. Input devices Or tools are used for entering data into the

computer such as barcode scanners and touch screens

HARDWARE COMPONENTS

3. Output Devices- Are peripheral devices that convert machine-

readable information into people readable form such as monitor, printer, plotter and voice output device

HARDWARE COMPONENTS

4. Secondary Storage Also called auxillary storage Used to store data and programs when they

are not being processed More permanent than main memory as data

and programs are retained when the power is turned off

HARDWARE COMPONENTS

5. Processing Devices Are included in the system unit where

computer program instructions are executed and data are manipulated

•It includes the central processing unit (CPU), main memory, motherboard and disk drives•The CPU contains the control unit, the arithmetic and logic unit (ALU)

CPU

HARDWARE COMPONENTS

5. Processing Devices5.1 The Control Unit- is the part of the CPU or

other device that directs the operation and controls the activity of the entire computer system

5.2 ALU- Arithmetic Logic Unit- is a part of the computer that carries out arithmetic and logic operations by computer instruction

HARDWARE COMPONENTS

5.2 ALU- Arithmetic Logic Unit- In some processors it is divided into 2 units

an arithmetic unit (AU) and a Logic Unit (LU) Some processors contain more than 1 AU,

one for fixed point operations and another for floating point operations

HARDWARE COMPONENTS

5.3 The ALU includes a group of registers that are high-speed memory locations built directly into the CPU used to hold data that are being processed

HARDWARE COMPONENTS

5.3 Cache Memory Is a special type of internal memory used by

CPU to increase performance or throuhput

PROCESSING CHARACTERISTICS AND FUNCTIONS

1. Machine cycle Time or access time is the time when the CPU executes an instruction measured in nanoseconds

PROCESSING CHARACTERISTICS AND FUNCTIONS

2. Clock speed- refers to the number of electronic pulses the CPU produces at a predetermined rate, which affects the machine cycle time

PROCESSING CHARACTERISTICS AND FUNCTIONS

3. Word Length- is simply a fixed-sized group of bits that are handled together by the machine. It is usually has a word size of 16, 32 or 64 bits

MEMORY

1. Main Memory Contains the programs that are currently

being run and the data the programs are opening on

MEMORY

A. Random Access Memory (RAM) Has 2 memory devices, static RAM (SRAM) or

dynamic RAM (DRAM) SRAM retains its contents while power is on

but unleashed when off DRAM has an extremely short data lifetime

like four milliseconds even when power is applied constantly

MEMORY

B. Read-only memory (ROM) Has the ability to retain data and programs

even during power failure and it provides permanent storage for instructions such as programs the computer manufacturer embedded

MEMORY

2. Programmable ROM (PROM) Is purchased in an unprogrammed state. The

process of writing your data in the PROM involves a special place of equipment called a device programmer

MEMORY

3. Erasable and Programmable ROM (EPROM) Is programmed exactly like PROM however it

can be erased and reprogrammed repeatedly

MEMORY

4. Hybrid Memories Can be read and written like a RAM, but

maintain its contents without electrical power like ROM

MEMORY

5. Electrically erasable and programmable ROM (EEPROM) are similar to EPROMs but the erase operation is accomplished electrically rather than by exposure to ultraviolet rays

MEMORY

6. Flash Memory Devices are high density, low cost,

nonvolatile, fast (to read but not to write) and electrically re-programmable

MEMORY

7. Non-volatile RAM (NVRAM) Is like an SRAM with a battery backup.

NVRAM operates when the power is turned on, just like any other SRAM

When turned on the NVRAM draw enough power from the battery to retain its data

SECONDARY STORAGE DEVICE

1. Magnetic Tapes Are magnetically coated strip of plastic on

which data can be encoded

SECONDARY STORAGE DEVICE

2. Magnetic Disk Is a round plate on which the data can be

encoded2.1 Floppy Disk- is a soft magnetic disk that

flops, slower to access than hard disks and have less storage capacity ( 1.2 MB- 1.4MB)

2.2 Hard Disk- can store from 10 to more than 100 gigabytes, it consists of several platters

SECONDARY STORAGE DEVICE

2.2 Hard Disk- all the read and write heads are attached to a single access arm so that they cannot move independently

2.3 Removable Cartridges- are hard disks encased in a metal or plastic cartridge that are removable like floppy disks, as capacious and as fast as hard disks and have the portability of floppy disks

SECONDARY STORAGE DEVICE

3. Optical Disk- records data by burning microscopic holes on the surface of the disk with a laser. To read the disk, another laser beam shines on the disk and detects the holes by changes in the reflection pattern. It can store up to 6 gigabytes

SECONDARY STORAGE DEVICE

3. Optical Disk3.1 Compact disc-read-only memory (CD-

ROM)- is an optical disk capable of storing information up to 1 gigabyte, ideall for storing information that requires large storage capacity and for software applications that support color, graphics, sound and especially video

SECONDARY STORAGE DEVICE

3.2 CD-Rewritable (CD-RW)- is a type of compact disk that enables you to write onto it in multiple sessions. It can read CD-ROMS but it cannot write a normal CD-ROMs

3.3 Digital Versatile disk (DVD) or Digital Video- is a type of optical disk technology to the CD-ROM, it holds a minimum of 4.7 GB of data enough for a full length movie

SECONDARY STORAGE DEVICE

4. Redundant Array of Independent/ Inexpensive Disks (RAID)-is a storage system that links any number of disk drives (disk array) so they act as a single disk for better performance and redundancy

SECONDARY STORAGE DEVICE

5. Storage Area Network (SAN)- is a high speed sub-network of shared storage devices that makes all storage devices available to all servers on a LAN or WAN

SECONDARY STORAGE DEVICE

6. Memory Card or Flash Memory Card- is a solid-state electronic flash memory data storage device used with digital cameras, handheld and laptop computers, telephones, music players, video games, consoles and other electronics

SECONDARY STORAGE DEVICE

7. Memory Stick- is a propriety standard invented by Sony that uses a serial interface data between the host device and card

SECONDARY STORAGE DEVICE

8. Universal serial Bus (USB) flash drives- are typically small lightweight, removable and rewritable with a memory capacity ranges from megabytes to gigabytes

SECONDARY STORAGE DEVICE

9. Multimedia Card- (MMC)- is used as storage media for a portable device and can easily be removed by access by a PC. A digital camera uses a MMC, with an MMC reader, a user could copy the pictures taken with digital camera off to his computer

SECONDARY STORAGE DEVICE

10. Secure Digital Card (SD card)- is a flash memory, non-volatile memory card format used in portable devices like digital cameras and handheld computers.

INPUT DEVICES

1. Personal Computer Input Devices1.1 Keyboard- is a peripheral input device

modeled after the typewriter keyboard, for input of text and characters and also to control the operations of a computer

INPUT DEVICES

1.2 Mouse- is a device that controls the movement of the cursor or pointer on a display screen

1.2.1 Mechanical Mouse- has rubber metal ball on its underside that can roll in all directions

1.2.2 Optical Mouse- uses a laser to detect the mouse’s movement

1.2.3 Serial Mouse- connect directly to an RS-232C serial port or a PS/2 port

INPUT DEVICES

1.2.4 USB Mouse- connects through a USB port1.2.5 Cordless Mouse- is not physically

connected at all, instead it relies on infrared or radio waves to communicate with the computer

INPUT DEVICES

2. Voice Recognition devices- use microphones and special software to record and convert the sound of the human voice into digital signals

INPUT DEVICES

3. Terminals- are input devices that perform data input, A terminal is connected to a complete computer system including a processor, memory and a secondary storage

INPUT DEVICES

4. Touch Sensitive screens- function as input and output devices by touching certain parts of a sensitive screen.

INPUT DEVICES

5. Bar- code scanners- employ a laser scanner to read the bar-coded label

INPUT DEVICES

6. Optical data readers- can be used to scan documents

2 categories:a. Optical mark recognition (OMR)b. Optical character recognition (OCR)

INPUT DEVICES

7. Point-of-sale (POS) devices- are terminals used in retail operations to enter sales information into the computer system

INPUT DEVICES

9. Automatic Teller machine (ATM) devices is a special purpose input and output device and terminal where bank customers perform withdrawals and other transactions for their bank accounts

INPUT DEVICES

10, Radio Frequency Identification (RFID)- technology employs a microchip called smart tag with an antenna that broadcasts its unique 96-bit identifier and location to corresponding receivers

OUTPUT DEVICES

Visual Display Units(VDU) monitors- are used to visually interface with the computer and are similar in appearance to TV

OUTPUT DEVICES

Features of Visual Display Unit1.1 size- usually 14-19 inches1.2 Resolution- determined how clear and

detailed the image is (pixels)1.3 refresh rate- how often the picture is

redrawn on the monitor1.4 Type- determines what resolutions are

available and how many colored can be displayed

OUTPUT DEVICES

Features of Visual Display Unit1.5 Color- 16 to 256 to 64 thousand to 16.7

million colors1.6 Scan Pattern- there are 2 patterns used by

different monitors to cover the whole screenNon-interfaced and interfaced.

PRINTERS AND PLOTTERS

Printer- puts on paper what you see on your monitor by printing you create a hard copy

2 Main types of printer1. Impact printer- which uses a number of metal

pins which strike an inked ribbon placed between the print head and the paper

2. Non-impact printer- uses ink spray or toner powder.

PRINTERS AND PLOTTERS

Plotters- are used to produce graphs and diagrams for buildings and engineering drawings

Two main types:1. Pen Plotters-have an ink pen attached to

draw the images2. Electronic Plotters- work similarly to a laser

printer

COMPUTER SYSTEM TYPES

1. Palmtops or Personal Digital assistant (PDA) Are highly integrated computers that often

use flash memory instead of a hard drive for storage

COMPUTER SYSTEM TYPES

2. Laptops or Notebooks- are portable computers that integrate the display, keyboard, a pointing device or trackball processor, memory and hard drive in all battery operated package slightly larger than an average hardcover book

COMPUTER SYSTEM TYPES

3. Thin client- is a low-cost, centrally managed computer that is devoid of a DVD player, internal disk drive and expansion slots

COMPUTER SYSTEM TYPES

4. Workstation- is a part of a computer network and has more than a regular desktop PC like memory, storage space and speed

COMPUTER SYSTEM TYPES

5. Server- runs a network computers. It handles the sharing of equipment like printers and the communication between computers on the network

COMPUTER SYSTEM TYPES

6. Mainframe computers- are large and expensive computers manly used to government institutions and large companies to bulk data processing such as censuses, industry consumer statistics, bank transaction processing

COMPUTER SYSTEM TYPES

Supercomputers- are mostly comprised or multiple, high performance computers working in parallel on a single system.

HISTORY OF COMPUTERS