Overview Of A Computer System.

7/28/2019 Overview Of A Computer System.

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Introduction to computer and its components

Computer hardware

Computer software

System unit and memory



Computer :

A set of tools that helps you perform informationprocessing tasks.

An electronic device that inputs, stores, processesdata and generates the useful information.



Two major components of computer:

Hardware:

- Consists of the physical devices that make up your computer system.

- An equipment that processes data to create

information includes input, output, storage andprocessing device.

Software (also called as a program) :

- Set of instructions that your computer hardwareexecutes to process information for you.

- Step by step instruction that tell the computer how todo the work .

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Hardware includes all of those devices that you can touch – monitor, keyboard, a floppy disk and etc.

6 categories of computer hardware:

1. Input devices for capturing information.

2. Output devices for presenting information.3. CPU and RAM for creating new information.

4. Storage devices for storing information.

5. Telecommunication devices for communicatinginformation.

6. Connecting devices for moving information to and fromyour various hardware.

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1. Input devices

Captures information and translates it into a form thatcan be processed and used by other parts of your computer.

Eg: use scanner to capture images, video camera to

capture your likeness in the form of a video, keyboard tokey in data, mouse to click the operation button, andetc.

2. Output devices

Takes information within your computer and present it ina form that you can understand.

Complement to input devices – while input devices helpyou enter information into a computer system, outputdevices help you see, hear or otherwise receiveinformation stored within your computer system.

Eg: use a set of speakers to hear music.

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3. CPU and RAM

The most important components of hardware together make up the real brains of computer.

The central processing unit (CPU or processor ) is the chipthat carries out instructions it receives from software.

RAM (Random Access Memory) is temporary memorythat holds software instructions and information for theCPU. It is rather like your short-term memory when youturn off your computer, all information in RAM is gone.

4. Storage devices

Temporary information storage in RAM is not enough need a means to more permanently store information soyou can recall and use it at a later time.

A storage device stores information so you can recalland use that information at a later time. Eg: disk drive,hard drive, DVD-RW drive, CD-ROM drive.

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http://en.wikipedia.org/wiki/File:Memory_module_DDRAM_20-03-2006.jpg



5. Telecommunication devices Telecommunication devices help

communicate information to people in other location. Eg: cell phones, email, digitalpagers, modem, network card and etc.

6. Connecting devices Computer contains a variety of connecting

devices so that information can move aroundall your hardware.

For example: you need some sort of

connection between your computer and aprinter.

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Input devices – for capturing information

Output devices – for presentinginformation

System unit – for creating new informationand data processing

Storage – for storing information

Telecommunication devices – for communicating information

Connecting devices – for movinginformation to and from various hardware

HA

RDWAR

E

Keyboard, Mouse, Microphone,Scanner, Digital Camera and

Web Cam

Monitor, Speaker and PortableMedia Player

Memory ,Central Processing Unit(CPU), Motherboard, Power

Supply

Hard Disk, Compact Disc, USBFlash Drive, Memory Card

Modem and Network Card

Cables, Telephone Lines,Satellite



SO

FTWAR

E

SystemSoftware

ApplicationSoftware

1. Uses to run computer.2. To control and maintain the operation of

computer and its devices.3. Serve as the interface between computer

hardware, user and application software.4. Example: Operating System (Windows,

Linux,Unix) and Utility Program (Antivirus).

1. Program designed to make user moreproductive.

2. Assist user to with personal task and perform

specific information processing task such aswriting term paper, and creatingpresentation slide, and writing and program.

3. Example: Microsoft Office 2007, MicrosoftPowerPoint 2007,spreadsheets,games,inventory program.

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All computer system have a system unit. System unitcontains most of the computer’s electronic components.

The basic components in the system unit, including thesystem board, microprocessor, memory, system clock ,expansion slots and cards, bus lines, ports, cables andpower supply units.

System board – connects all system components to oneanother.

Microprocessor – controls operations and performsarithmetic and logical operations.

Memory – holds data, instructions, and information.

System clock – emits a beats or pulse that sets theoperating pace for all of the components in the systemunit.

Expansion slots – provide connections for expansioncards to the system board.

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Expansion card – allow external devices to connect toand expand a computer’s capability.

Bus lines – provide data pathways that connect varioussystem components.

Ports – socket for external devices to connect to thesystem unit.

Cables – connect exterior devices to the system unit viathe ports.

Power supply unit – converts AC (alternating current) toDC (direct current), providing power to the system unit.

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1. Desktop system units

Typically contain the system’s electronic componentsand selected secondary storage devices.

Input and output devices, such as mouse, keyboard

and monitor are located outside the system unit.2. Notebook system units

Portable and much smaller.

These system units contain the electronic components,selected secondary storage devices, and input devices

(keyboard and pointing device). Located outside thesystem unit, the monitor is attached by hinges.

Often called laptops.

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3. Table PC system units

Similar to notebook system units.

Highly portable device that supports the use of a stylus or pen to input commands and data.

4. Handheld computer system units

The smallest and are designed to fit into the palm of onehand.

Also known as palm computer, this system contains anentire computer system, including the electroniccomponents, secondary storage, and input/outputdevices.

Personal Digital Assistants (PDAs) are the most widely usedhandheld computers.

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While the actual size may vary, each type of SU has the samebasic system components including system board,microprocessor, and memory. However…

HOW DO WE AS HUMAN BEINGS COMMUNICATE WITH AND

CONTROL ALL THIS ELECTRONIC CIRCUITRY… ???



Computers cannot recognize information the same way youand I can.

People follow instructions and process data using letters,numbers and special characters. For example: if we wanted

someone to add the numbers 3 to 5 together and recordthe answer, we might say “please add 3 and 5.”

However… the system unit, is electronic circuitry andCANNOT directly process such a request because itCANNOT UNDERSTAND.

Therefore…

Before any process can occur within the system unit, aconversion must occur from what we understand to whatthe system unit can ELECTRONICALLY process.

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What is the most fundamental statement you can makeabout ELECTRICITY ???



It is simply this:

It can be either on or off. Indeed, there are many formsof technology that can make use of this two-stateon/off, yes/no, present/absent arrangement.

For instance, a light switch may be on or off, or anelectric circuit open or closed.

This is the reason, then, that a two-state or binary systemis used to represent data and instructions.

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What is the BINARY SYSTEM ???



The decimal system that we’re all familiar with has 10 digits(0, 1, 2, 3, 4, 5, 6, 7, 8, 9).

The binary system, however consists of only two digits (0and 1). Each 0 or 1 is called a bit (short for binary digit).

In the system unit, the 0 can be represented by electricity

being off, and the 1 by electricity being on. In order to represent numbers, letters, and special

characters, bits are combined into groups of eight calledbytes. Each byte typically represents one character.

Now, let us consider an important question…

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HOW ARE CHARACTERS REPRESENTED AS 0s AND 1s(“off” and “on” electrical states) IN THE COMPUTER ???



The answer is…

by using of Binary Coding Scheme…

When you press key on the keyboard, a character is

automatically converted into a series of electronic pulsesthat the system can recognize.

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Code Uses

ASCII(pronounced “as-key”)

stands for American StandardCode for Information Interchange.

most widely used for

Microcomputers

EBCDIC

(pronounced “eb-see-

dick”)

stands for E xtended Binary

Coded Decimal Interchange

Code. developed by IBM and is used

primarily for large computers

Unicode a 16-bit code originally designed

to support International languages

like Chinese and Japanase.

The most popular,use 8 bits (1 byte)



The system board is also known as the main board or motherboard.

It is the communications medium for the entire computer system. Every components of the system unit connects tothe system board.

It acts as a data path allowing the various components tocommunicate with one another.

For example, external devices such as the keyboard, mouseand monitor could not communicate with the system unitwithout the system board.

It is a large flat circuit board covered with a variety of

different electronic components including sockets, slots andbus lines.

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In a microcomputer system, the central processing unit (CPU) or processor is contained on a single chip called microprocessor.

The microprocessor is “brains” of the computer system.

It has two basic components:

1. Control unit :

Tells the rest of computer system how to carry out a program’s instructions.

It directs the movement of electronic signals between memory, whichtemporarily holds data, instructions, and processed information, and thearithmetic logic unit.

It also directs these control signals between the CPU and input/output devices.

2. Arithmetic logic unit :

Usually called ALU, performs two types of operations: arithmetic and logical.

Arithmetic operations as you might expect, are the fundamental math

operation (addition, subtraction, multiplication and division).

Logical operations consist of comparison of two pieces of data (=, <, >)

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Chip capacities are often expressed in word sizes. A word isthe number of bits (such as 16, 32, or 64) that can beaccessed at one time by the CPU.

The more bits in a word, the more powerful and faster thecomputer is.

Eight bits group together to form a byte. So, a 32-bit-wordcomputer can access 4 bytes at a time. Then, a 64-bit-wordcomputer can access 8 bytes at a time. (Therefore, thecomputer designed to process 64-bit-word is faster).

The two most significant recent developments inmicroprocessors are:

1. 64-bit processor powerful and faster microcomputer.

2. Dual-core chip

provides two separate and independent CPUs

allows a single computer to run two programs at the sametime – parallel processing

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Memory is a holding area for data, instructions, andinformation.

Like microprocessors, memory is contained on chipsconnected to the system board.

There are three well-known types of memory chips:

1. Random-access memory (RAM) Hold the program (sequence of instructions) and data that

the CPU is presently processing.

Called as temporary or volatile storage – everything in most

types of RAM is lost as soon as the microcomputer is turned

off (also lost if there is a power failure or other disruption of

the electric).

Cache memory or RAM cache improves processing by

acting as a temporary high-speed holding area between the

memory and the CPU computer detects which information

in RAM is most frequently used. It copies that information into

the cache. When needed, the CPU can quickly access the

information from the cache.22



2. Read-only memory (ROM)

ROM chips have programs built into them at the factory.

Unlike RAM chip, ROM chips are not volatile and cannot bechanged by the user.

“Read only” means that the CPU can read, or retrieve data andprograms written on the ROM chip. However, the computer cannot write (encode or change) the information or instructions.

Typically contain special instructions for detailed computer operations. For example: instructions to start a computer.

3. Complementary metal-oxide semiconductor (CMOS)

CMOS chip provides flexibility and expandability for a computer system.

It contains essential information that is required every time thecomputer system is turned on - current date and time, amountof RAM, type of keyboard, mouse, monitor and disk drive.

Unlike RAM, it is powered by a battery and does not lose itscontents when the power is turned off. Unlike ROM, its contentscan be changed to reflect changes in the computer system – such as increased RAM and new hardware devices.

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The system clock is located on a small specialized chip thatproduces precisely timed electrical beats or impulses.

The system clock emits a beat or pulse that sets theoperating pace for all of the components in the system unit.

A computer’s system clock has a fixed speed that cannot

be varied. For that reason, a computer system’s clock speed is an important measurement indicating the speedof processing or power of a computer system.

The clock speed or clock rate for powerful microcomputersis measured in gigahertz (GHz) or billions of beats per second – the faster the clock speed, the faster the

computer can process instructions.

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Most microcomputers have open architecture – allow users toexpand their systems by providing expansion slots on thesystem board.

Users can insert optional devices known as expansion cards into these slots.

There are a wide range of different types of expansion cards.

Some of the most commonly used expansion cards are:

1. Video cards: also known as graphics cards. These cards connectthe system board to the computer’s monitor. The cards convert theinternal electronic signals to video signals so they can be displayedon the monitor.

2. Sound cards: accept audio input from a microphone and convert it

into a form that can be processed by the computer. These cardsconvert internal electronic signals to audio signals so they can beheard from external speakers.

3. Modem cards: also known as internal modem. These cards allowdistant computer to communicate with one another by convertingelectronic signals from within the system unit into electronic signalsthat can travel over telephone lines and other types of connection.

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3. Network interface cards (NIC): also known as network adapter cards, are used to connect a computer to one or more other computers – users can share data, programsand hardware. NIC typically connects the system unit to acable that connects to the network.

4. TV tuner cards: can watch television, capture video, andsurf the internet at the same time.

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Expansion cards fit into slots on the system board



A bus line also known simply as a bus – connects the parts of theCPU to each other.

Buses also link the CPU to various other components on the systemboard.

A bus is a pathway for bits representing data and instructions. Thenumber of bits that can be travel simultaneously down a bus isknown as the bus width.

A bus is similar to a multilane highway that moves bit rather thancars from one location to another. The number of traffic lanesdetermines the bus width.

A highway (bus line) with more traffic lanes (bus width) can movetraffic (data and instructions) faster – is an important factor relating

to the speed and power for a particular computer. For example, a64-bit bus is twice as fast as a 32-bit bus.

Every computer system has two basic categories of buses:

1. System buses: connect the CPU to the memory on the systemboard.

2. Expansion buses: connect the CPU to other components on thesystem board.

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Figure 8: Bus



A port is socket for external devices to connect to the system unit.

Some ports connect directly to the system board while other connect to cards that are inserted into slots on the system board.

Many ports, like the mouse, keyboard, and video ports, are for specific devices. Others, like those listed below, can be used for avariety of different devices.

1. Serial ports:

are used for a wide of purposes. They are often used toconnect a mouse, keyboard, modem, and many other devices to the system unit.

Send data one bit at a time and very good for sendinginformation over a long distance.

2. Parallel ports:

are used to connect external devices that need to send or receive a lot of data over a short distance.

Typically send eight bits of data simultaneously across eightparallel wires.

Mostly used to connect printers to the system unit.

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3. Universal serial bus (USB) ports:

gradually replacing serial and parallel ports.

Faster, and one USB port can be used to connectseveral devices to the system unit.

4. FireWire ports: also known as high-performance serial bus (HPSB) ports.

As fast as USB 2.0 ports and provide connections tospecialized FireWire devices such as camcorders.

29Ports



A computer (or computer system) is a set of tools that helpsyou perform information-processing tasks.

Your computer tools are either hardware or software.

Software

System software: for technology-specific and essential tasks.

Application software: for specific tasks such as writing a paper or managing inventory.

Hardware

Input devices: such as a mouse for capturing information.

Output devices: such as a printer for presenting information.

CPU and RAM: your computer’s brain, for creating newinformation.

Storage devices: such as a disk for storing information.

Telecommunication devices: such as a modem for communicating information to other people.

Connecting devices: such as a port for moving informationaround all your hardware.

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System unit contains electronic components. Four basic types are: desktop, notebook, tablet PC, and handheld.

Data and instructions can be represented electronically with a two-

state or binary system of numbers (0 and 1). Each 0 or 1 is called a

bit. A byte consists of eight bits and represents one character.

Binary coding schemes convert binary data into characters. Three

such schemes are:

ASCII – the most widely used for microcomputers.

EBCDIC – developed by IBM; used primarily by larger

computers.

Unicode – 16-bit code; originally designed to support

international languages like Chinese and Japanese.

To be a competent end user, you need to understand how data

and programs are represented electronically.

Additionally, you need to understand the functionality of the basic

components in the system unit: system board, microprocessor,

memory, system clock, expansion slot and cards, bus lines and

ports. 31

Overview Of A Computer System.

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