Semester One 2001/2002

Sheffield Hallam University 1

What is a Computer?

• System for storage, processing, communication of information– Hardware refers to physical

components which, if dropped, would break!

– Software is the term for sets of programs: specially coded instructions that tell the hardware how to behave

Semester One 2001/2002

Sheffield Hallam University 2

What is a Personal Computer?

• Generally any computer small and cheap enough to be owned by one person - Archimedes, Macintosh, Atari etc.

• Ususally refers to particular type - IBM compatible

• Commonly known as PC

Semester One 2001/2002

Sheffield Hallam University 3

IBM and Clones

• In 1981 IBM produced first PC– cost £3000– 1% of power of today’s machines

• Other companies made ‘clones’– higher specifications– lower cost

• Now very few PCs are actually IBM

Semester One 2001/2002

Sheffield Hallam University 4

IBM and Clones

• Operating System is a set of programs to:– enable user communication– control behind-the-scenes activity

• Microsoft supplied OS for IBM PCs– PC-DOS (Disk Operating System)

• Also sold as MS-DOS to clone makers

Semester One 2001/2002

Sheffield Hallam University 5

Overview of PC Components

• System unit• Monitor• Keyboard and mouse• Printer• Software

Semester One 2001/2002

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System Unit• Otherwise known as computer or

machine• Case with buttons, lights, slot for

floppy disks, plug sockets at the rear• Inside

– hard and floppy disk drives– motherboard– processor, memory and expansion slots

Semester One 2001/2002

Sheffield Hallam University 7

Monitor

• Looks like a TV– most frequently used output device

• means of viewing the results of the computer’s processing

– connects to the system unit by two cables• one draws power• other receives information from display

adaptor housed on motherboard

Semester One 2001/2002

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Keyboard and Mouse

• Both input devices• Keyboard communicates

characters typed via multi-core cable (signal and power)

• Mouse is most common pointing device– communicates different things

according to position when clicked

Semester One 2001/2002

Sheffield Hallam University 9

Printer

• After monitors, printer most common output device

• Unlike components so far, printer can be bought separately from PC package

• Two basic types:– impact (Dot Matrix)– non-impact (Laser and Inkjet

Semester One 2001/2002

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Software

• Minimum software requirement is OS

• Other kinds of software are applications– word processors– spreadsheets– games– programming languages

Semester One 2001/2002

Sheffield Hallam University 11

Desktops and Notebooks• Desktops

– sit on your desk and don’t move often– plenty of room inside for expansion

and upgrading

• Laptops– first of the portable PCs around 1980s

• Notebooks– size of a telephone directory– much dearer than desktops