DESCRIBING COMPUTER ORGANIZATION – HARDWARE

& SOFTWARE

Chapter 1.1:

What is Programming?

Computer programming the art and science of designing and writing computer

programs.

Computer program a sequences of instructions written in a programming

language to achieve a task/to solve a problem.

What is a computer?

HardwareThe physical, tangible parts of a computer keyboard,

monitor, disks, wires, chips, etc.

SoftwarePrograms and data A program is a series of instructions

A computer requires both hardware and software

Each is essentially useless without the other

Computer Organization

Computer System Organization

Hardware• CPU• Main Memory (RAM)• Secondary Storage• I/O Device

Software• System Programs• Application

Programs

Hardware Components of a Computer

Hardware Components of a Computer – motherboard

processor chipadapter cards

memory chips

memory slots

motherboard

Expansionslots for adapter cards

Hardware Components of a Computer CPU

Brain of the computer, most expensive, the faster computer.

CPU components– control unit, program counter, register instruction, arithmetic logic unit, accumulator.

RAMTemporary memory, volatile, directly connected

to the CPU, using memory cells unit.

Hardware Components of a Computer SECONDARY STORAGE

Provides permanent storage for information.Examples of secondary storage:

○ Hard disks○ Floppy disks○ Zip disks○ CD-ROMs○ Tapes.

RAM vs Secondary Storage

Primary memory Volatile Fast Expensive Low capacity Works directly with the processor

Secondary Storage Nonvolatile Slow Cheap Large capacity Not connected directly to the processor

Hardware Components of a Computer INPUT DEVICES

Sheet-fed

Hardware Components of a Computer OUTPUT DEVICES

CPU and Main Memory

CentralProcessing

Unit

MainMemory

Chip that executes program commands

Eg.Intel Pentium 4Sun ultraSPARC III

Primary storage area for

programs and data that are in

active use

Synonymous with RAM

Secondary Memory Devices

CentralProcessing

Unit

MainMemory

Floppy Disk

Hard Disk

Secondary memorydevices providelong-term storage

Information is movedbetween main memoryand secondary memoryas needed

Hard disksFloppy disksUSB drivesWritable CDsWritable DVDsTapes

Input / Output Devices

CentralProcessing

Unit

MainMemory

Floppy Disk

Hard Disk

Monitor

Keyboard

I/O devices facilitateuser interaction

Monitor screenKeyboardMouseJoystickBar code scannerTouch screen

Software

In contrast to hardware, software is an abstract, intangible entity.

Software can be categorized as system or application software (refer next slide)

It consists of program and data to be used to perform certain tasks

A program is a sequence of simple steps and operations, stated in a precise language that the hardware can interpret

The process of programming involve algorithm design & coding.

Software Categories

System Software Systems programs keep all the hardware and software

running together smoothly The most important system software is the operating

system (OS) controls all machine activities provides the user interface to the computer manages resources such as the CPU, memory & I/O Windows XP, Unix, Linux, Mac OS

Application Software generic term for any other kind of softwares word processors, Spreadsheets, Web browsers, games

Algorithm

Algorithm refers to the strategy to solve a problem

It is a clear step by step sequence of instructions that describes how to accomplish a certain task.

2 ways can be used to represent algorithm:a) pseudocode

○ using english-like-phrases to describe the algorithm

b) flowchart○ using diagrams that employ the symbol to describe the

algorithm.

Coding

Algorithm need to be translated into computer language so that it can be executed

Coding refers to the process of expressing algorithm in a programming language

The product of coding is a program. The act of carrying out the instructions

contained in a program is called program execution

A computer program is stored internally as a series of binary numbers known as the machine language of the computer

Digital Information

Computers store all information digitally:numberstextgraphics and imagesvideoaudioprogram instructions

In some way, all information is digitized - broken down into pieces and represented as numbers

Representing Text Digitally

For example, every character is stored as a number, including spaces, digits, and punctuation

Corresponding upper and lower case letters are separate characters

H i , H e a t h e r .

72 105 44 32 72 101 97 116 104 101 114 46

American Standard Code for Computer InterChange (ASCII) The ASCII data set 128 characters (0 until 127) Character A in ASCII 01000001

Binary Numbers

Once information is digitized, it is represented and stored in memory using the binary number system

A single binary digit (0 or 1) is called a bit

A byte consists of 8 bits. Each byte in main memory resides at a

numbered location called its address.

Memory

Main memory is divided into many memory locations (or cells)

927892799280928192829283928492859286

Each memory cell has a numeric address, which uniquely identifies it

Storing Information

927892799280928192829283928492859286

Large values arestored in consecutivememory locations

10011010Each memory cell stores a set number of bits (usually 8 bits, or one byte)

Main Memory

Storage Capacity

Every memory device has a storage capacity, indicating the number of bytes it can hold

Capacities are expressed in various units:

KB 210 = 1024

MB 220 (over 1 million)

GB 230 (over 1 billion)

TB 240 (over 1 trillion)

Unit Symbol Number of Bytes

kilobyte

megabyte

gigabyte

terabyte