Copyright © 2006 by The McGraw-Hill Companies, Inc. All rights reserved.

McGraw-Hill Technology EducationMcGraw-Hill Technology Education Copyright © 2006 by The McGraw-Hill Companies, Inc. All

rights reserved.

Edited by: Edited by: Rahman Ali, Lecturer in Rahman Ali, Lecturer in Computer Science, QACC, Computer Science, QACC, University of PeshawarUniversity of Peshawar

Copyright © 2006 by The McGraw-Hill Companies, Inc. All rights reserved.

McGraw-Hill Technology Education

Chapter 1B

Looking Inside the Computer SystemLooking Inside the Computer System

1B-3

Parts of the Computer System

• Computer systems have four parts– Hardware– Software– Data– User

1B-4

Parts of the Computer System

• Hardware– Mechanical devices in the computer– Anything that can be touched

• Software– Tell the computer what to do– Also called a program– Thousands of programs exist

1B-5

Parts of the Computer System

• Data– Pieces of information– Computer organize and present data

• Users– People operating the computer– Most important part– Tell the computer what to do

1B-6

Information Processing Cycle

• All the steps that are followed to process data into information is called IPC.– Input– Processing– Output– Storage

Information Processing Cycle

1B-7

1B-8

Essential Computer Hardware

• Computers use the same basic hardware

• Hardware categorized into four types:– Input – Memory devices– Processor– Output– Storage

Essential Computer Hardware

1B-9

1B-10

Input devices

• Input devices– Allows the user to interact with the

computer– Input devices accept data

• Keyboard, mouse

1B-11

Memory devices

• Memory devices– Computer Memory are internal storage

areas in the computer used to either temporarily or permanently store data or instructions to be processed

Memory devices

• Types of memory– Primary memory is also called

• main memory or internal memory or volatile memory)

1B-12

Memory devices …

• Primary memory– RAM– ROM– CPU registers– Cache memory

1B-13

Memory devices …• Random Access Memory (RAM)

– RAM is a type of memory device within the computer system which is responsible for storing data on temporary basis

– The data from the RAM is washed out when it is switched off

– The data from the RAM is accessed by the processor for processing

1B-14

Memory devices

• RAM types– Static RAM (SRAM):

• Not refreshed, more power consumption, faster than DRAM

– Dynamic RAM (DRAM):• Refreshed regularly, consume less power,

slower than SRAM• Examples are:

– SDRAM, DDR and Rambus DRAM

• Size of RAM– 2GB, 4GB, 8GB, 16GB and 24GB (installed on

Core i7)1B-15

Memory devices …

• Read Only Memory (ROM)– This type of memory is active, regardless of

whether the system is turned on or is switched off. – It is a kind of permanent non-volatile storage

memory. – As the name 'read only' suggests, the contents in it

cannot be changed or modified. – It is an integrated circuit which is pre-programmed

with important data that should necessarily be present for the computer to carry out its normal functionalities.

1B-16

Memory devices …

1B-17

• ROM chips– It usually contains a small startup program

(BIOS) that is used to bootstrap the computer

Memory devices …

• Read Only Memory (ROM) Types– ROM –

• Read Only Memory

– PROM – • Programmable Read Only Memory : Programmed once

– EPROM – • Erasable Programmable Read Only Memory: Programed

many times

– EEPROM – • Electrically Erasable Programmable Read Only Memory

– Flash EEPROM memory

1B-18

Memory devices …

• CPU register– Processor registers are located inside the

processor. – Each register typically holds a word of data

(often 32 or 64 bits). – Registers are the fastest of all forms of

computer data storage.

1B-19

Memory devices …

• Cache memory– Processor cache is an intermediate stage between

ultra-fast registers and much slower main memory– It is used to reduce the speed mismatch between

fastest speed registers and slow speed RAM – It's introduced solely to increase performance of

the computer. – Cache is divided into multiple level

• Level 1 (L1) cache or primary cache – being smallest, fastest and located inside the processor

• Level 2 (L2) and Level 3 (L3) cache or secondary cache – larger and slower than level 1 and located outside the CPU on motherboard

1B-20

Memory devices …

1B-21

1B-22

Processing devices (CPU)

• Processing devices– Brains of the computer– Carries out instructions from the program– Manipulate the data– Most computers have several processors– Central Processing Unit (CPU)– Secondary processors– Processors made of silicon and copper

Processor

1B-23

Processor …

1B-24

Processor …

1B-25

Processor…• Components of processor

– CU (Control Unit): • The control unit control all the activities of the processor

• It communicates with both the arithmetic/logic unit and memory (registers)

– ALU (Arithmetic Logic Unit):• Perform arithmetic and logical operations

• Arithmetic operation: X=a+b

• Logical operation: – X>Y or – percentage>=70 && percentage<80 then grade=A

– Registers:• A processor register is a small amount of storage available as

a part of a CPU

• 64 bits registers and 128 bits registers are used in latest CPU’s

1B-26

Output devices

• Output devices deliver data– Monitor, printer, speaker

1B-27

Input/output devices

• Some devices are input and output both– Touch screens

1B-28

1B-29

Storage devices …

• Secondary storage (also known as external memory or auxiliary storage), is a permanent storage that stores a large volume of data

• It differs from primary storage in that it is not directly accessible by the CPU and is also a permanent storage

• Types of secondary storage– Magnetic storage– Optical storage

Storage devices …

• Magnetic storage– Floppy and hard drive– Uses a magnet to access data

1B-30

Storage devices …

• Optical storage– CD and DVD drives– Uses a laser to access data

1B-31

Storage devices …

• Other secondary storage devices– Flash Memory: This is another non-volatile

(permanent) kind of memory which is intended to contribute to portable storage and a convenient transfer of data from one computer to another

• Memory cards and • USB flash drives are some modes of this type of

memory storage.

1B-32

1B-33

Software Runs The Machine

• Softwares are the computers programs that tell the computer to perform a specific task

• Two types– System software– Application software

1B-34

Software Runs The Machine

• System software– These are the most important softwares

that control the computer hardwares and make them ready for users operations

System softwares• Types of system softwares

– Operating system• Is the most important system software that that controls

the computer hardwares and run other application softwares.

• Examples: Windows XP, Vista, Windows 7

– Network operating system (OS)• Allows computers to communicate and share data across

a network• Examples: Windows Server 2003

– Utility• These are computer programs that are used to perform

highly specialized tasks• Examples: Symantec AntiVirus, disk management,

calculator etc.1B-35

1B-36

Application software

• Application software– Accomplishes a specific task– Most common type of application softwares

• Word processing– MS Word

• Graphics• Spreadsheet

– MS Excel

• Database management– MS Access

• Multimedia • Web designing

1B-37

Computer data

• Fact with no meaning on its own

• Stored using the binary number system

• Data can be organized into files

• Always be in raw form

• Cannot be used for decision making purpose

• Always used as input to the computers

1B-38

Computer users

• Role depends on ability– Setup the system– Install software– Mange files– Maintain the system

• “Userless” computers– Run with no user input– Automated systems– Controlled by the installed operating system– Examples: washer and dryers machines, automatic

cars etc.

Copyright © 2006 by The McGraw-Hill Companies, Inc. All rights reserved.

McGraw-Hill Technology Education

Chapter 1B

End of ChapterEnd of Chapter