Computer Hardware SyStem

Course: COMP101 Subject: Computer Skills

Chapter: 3

What is a computer?

• An electronic device that accepts input, processes the data and

instructions, produces output from the processing that is useful

and meaningful and stores the results for future use.

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Computer Organization

• Computer organization refers to the operational units and their interconnections that realize the architectural specifications.

• Examples: – instruction set, – number of bits used to represent various data

types, – I/O mechanisms, – techniques for addressing memory.

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Four Main Sub-systems of Computer

• Memory • ALU (Arithmetic/Logic

Unit( • Control Unit • Input/output System

(I/O(

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CPU • Abbreviation for Central

Processing Unit. • The brain of the computer. • Three main parts:

– Control Unit (CU). – Arithmetic Logic Unit (ALU). – Registers .

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CPU Control Unit (CU) • It directs the

computer system to execute stored program instructions and communicates with other parts of the hardware.

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CPU - Arithmetic Logic Unit (ALU)

• Performs arithmetic operations

– Addition, Subtraction, Division and Multiplication

• Performs logical operations

– Less than, Greater than, Equal, etc…

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CPU - Registers

• a special, high-speed storage area within the CPU. – Store data before process – Store data after process. – It can hold address as well.

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Computer Memory

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What is Memory ?

• Memory is a large collection of circuits, each cell capable of storing a bit.

• Each cell assigned an address. • Two categories of memory:

– Primary memory • RAM • ROM

– Secondary (Auxiliary)

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RAM • Random Access Memory. • Also know as volatile memory. • Takes the same amount of time

to access any memory cell, regardless of its location.

• Hold instructions for processing data, processed data, and raw data.

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RAM (continue …..)

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ROM • Read Only Memory. • This type of memory cell can be

read from, but not written to. • ROM is non-volatile. • used to distribute firmware that is

software very closely tied to specific hardware.

• Does not require frequent updates. • Mainly there are three types of

ROM: – PROM, EPROM, EEPROM

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PROM • Programmable ROM • Programmed via a special

device called a PROM programmer.

• Can only be programmed once.

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EPROM • Erasable PROM. • Can be erased and re-

used. • Erasure is caused by

using an intense ultraviolet light.

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EEPROM • Electrically EPROM. • Allows its entire contents

(or selected banks) to be electrically erased.

• Can be found in camera, MP3 player, etc.

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Secondary Memory • Auxiliary memory is the lowest-cost, highest-

capacity, and slowest-access storage in a computer system.

• It is where programs and data are kept for long-term storage or when not in immediate use.

• Can be accessed: – sequentially. Example: magnetic tape – or directly. Example: Hard disc, DVD, Flash etc.

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Magnetic Tape • Consisting of a thin tape

with a coating of a fine magnetic material.

• Using tape drive to store data on the tape.

• Cheap and durable.

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Hard Disc • The main and usually

the largest data storage device in a computer.

• Made up of platters which stored the data, and read/write heads to transfer data.

• Can be used internally or externally.

• Many types: PATA, SATA, SCSI, SSD,

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PATA • Parallel Advanced

Technology Attachment.

• known as Integrated Drive Electronics (IDE) and Enhanced Integrated Drive Electronics (EIDE) drives .

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SATA • Serial Advanced

Technology Attachment. • Different connector than

PATA. • Different power adapter

than IDE. • More efficient, and use

less power than PATA ones.

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SCSI • Small Computer System

Interface. • Similar to IDE hard drives. • Spin at a higher rate in

comparison to IDE and SATA. • SCSI hard disks need a

controller that operates the interface between the drives and the computer motherboard.

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SSD • Solid State Drive. • No moving components. • Using semiconductors to

perform the function of data storage.

• Faster than other types of hard discs, but expensive.

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Optical Discs • It is flat, circular, plastic or

glass disk on which data is stored in the form of light and dark pits.

• Two basic types of optical disks: Read-only optical disks, and Rewritable Optical disks.

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CD • Known as “Compact Disk”, • Can store 80 minutes of continues video

recording. • The space of CD is up to 700 mb. • There are two types of CD :-

– CD ROM. – CD R/W.

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DVD

• Known as “Digital Versatile Disk”. • Storage capacity of DVD is up to 4.7GB. • Types of DVD :-

– DVD ROM. – DVD R/W.

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Memory and Storage Convertor

• Computers store information in the form of "1" and "0"s.

• Computer data is expressed as bytes. • But 1 kilobyte is 1024 bytes not 1000 bytes. • Data storage units are: bits, bytes, kilobytes,

megabytes, gigabytes, terabytes, petabytes, exabytes, zettabytes and yottabytes.

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Input / Output

Input Devices • Converts incoming data and

instructions into a pattern of electrical signals in binary.

Output Devices • Reverses the process,

translating the digitized signals into a form intelligible to the user.

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Input / Output Devices

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Input / Output Control Circuits • Every peripheral device

(keyboard, modem, monitor, etc.) requires a control circuit that interfaces with the computer's processor (CPU).

• Either built into the chips on the motherboard or are contained on plug-in cards.

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Advanced Input Devices (Imaginary Interfaces )

• A concept to which

users could spatially interact with screen-less devices and interfaces that existed only in the imagination.

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Non-Speech Voice Input • Detect speech-like

movement of the mouth, face, and throat even when no sound.

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Implantable Brain–computer interfaces (BCIs)

• Sensors are placed closest to the neurons (nerve cells) that carry the brain’s electrical signals.

• Allow direct recording of the activity in a subset of the brain’s neurons.

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Advanced Output Devices (Glasses) • Wearable computing has

long sought an effective mobile display built into eyeglasses.

• A simple version of this vision is an LCD-based display that clips onto one side of a pair of eyeglasses.

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Haptic Feedback • Use of our sense of touch

through programmable haptic output.

• Might enable a user to “feel” who is calling his/her phone, without needing to pull the phone out and glance at the display.

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Motherboard (System board) • A printed circuit board

holds the main electronic components of the system; like the central processing unit and memory.

• Provides the connectors for other peripherals such as printers, scanners, monitors, mouse, and keyboard devices.

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Types of Motherboards • AT motherboard. • ATX motherboard,

Advanced technology extended .

• LPX motherboard, low profile extension.

• The major difference between the LPX and previous boards is that the input and output ports in these boards are present at the back of the system.

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What to consider when buying a computer?

• CPU (Central Processing Unit).

• RAM (random access memory).

• Hard Drive. • Networking. • Ports. • Graphics Card.

• Optical Drives. • Peripherals. • Battery and Power

Consumption. • Size or "Form Factor“. • The most, however, to

consider is your requirements and budget.

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