LIS508 lecture 3: computer & input devices

1. LIS508 lecture 3: computer & input devices Thomas Krichel 2002-10-06

2. Admin news • Grades for the quizzes will be made available at • http://wotan.liu.edu/home/krichel/lis508w03a/grades/secret.html • where secret is your word, transliterated into all lowercase, example • seCret  secret • SecrEt  secret

3. Literature • Peter Norton “New inside the PC” chapter 1 and 5 • Ruth Maran and Paul Whitehead “Teach yourself computers visually”, chapter 1 and 3 • Hutchinson and Sawyer chapter 2 • White, part 5

4. Hardware and Software • Hardware is anything in the computer you can touch. • Software are the instructions that make the computer do things. • In early days, software was closely tied to hardware. It could only run on machines of a specific hardware and was useless on other machines.

5. structure • general things about computers • looking at computer hardware • bus • input devices • keyboard • mouse • other

6. Computers • An old distinction is the following • A Mainframe is a computer that are used by many people in an organization. They access it through terminals. • A personal computer is a machine that is used by only one person at a time. In olden days it could only do one thing at a time. • A PC is a special type of personal computer.

7. What is a PC • The PC was first brought out by IBM in 1981 • IBM published the design. • Processor chips supplied by Intel. • Software to run it was bought from Microsoft • Microsoft had the right to have other companies use the operating system. • A PC is any computer that basically follows this tradition. • Intel processor • Microsoft software

8. Basic parts of a PC • Display do not open • Input no need to open • Keyboard • Mouse etc • System Unit may be opened • Logic system • Display system • Storage system • Input output system • Communication system

9. Opening the system unit • Voltages used in the PC are 3 to 12 V • Be aware of static electricity, touch first unpainted part of case first • Keep power cable plugged in a grounded socket • Never open sealed part of the power supply

10. Logic system I • Motherboard • green plastic sheet • with traces and slots • usually complying to a standard called “plug and play” • Jumpers can set key features • Jumper wires stick out of the motherboard • Can be shortened with jumpers • Do not change unless you have to

11. The logic system II • CMOS or flash memory • Powered by battery • holds the Basic Input Output System (BIOS) • Central Processing Unit (CPU), recognizable through its fan • Cache memory for CPU • Main memory socket • The Bus (see later)

12. BIOS • Is the software that makes the components of the PC work together • When the computer boots it tells you how to “enter setup” • There you can make changes to the BIOS setting • The way that you do this is not standardized • It usually is a simple menu. • Be careful

13. Usual things to set in the BIOS • Set the hardware clock • Set processor speed setting • Tell the machine what disks you have • Power management options • Automatic wake up • Boot sequence setting

14. The Bus • Set of connections between devices in the system unit. Not very precisely defined • Types of bus • Industry Standard Architecture ISA bus (16 bit), old • Peripheral Component Interconnect PCI bus (32 bit) • Accelerated graphics port (AGP) bus, only for graphics

15. The CPU • Quality of CPU is a major component of the speed of the machine • Speed of the CPU is measured in Hertz, as the number of instructions per second. • Intel are the main manufacturer • Pentium • Celeron Processor • but other manufacturers may be offering better quality/price.

16. The components on the bus • The display system • Video card • Storage system • Hard disk • Floppy disk • CD-rom • CD-R • CD-RW

17. Other components on the bus • Modems, allow communication over a phone line • Internal modems with own serial device • It squeaks • Network interfaces • network cards

18. Input/Output components • Parallel port • Parallel because it can move a whole byte at a time • Mainly used for connection to a printer • Nowadays it can handle bidirectional traffic • Serial port • One bit at a time -- Uses thin cable • Slow -- inexpensive • Universal serial bus (USB) replaces those

19. Universal Serial Bus (USB) • It is a new, rectangular port device • 4 wires • 2 for power • 2 for communication • USB has a hub/slave technology • One USB line can connect to a hub • The hub has several outgoing lines, that connect to other devices • This is achieved by a complex set of software

20. Keys on a keyboard • Typewriter keys • Function keys • Arrow keys • Editing keys • Numeric keypad • Alt and Control keys • Escape, windows key • Obsolete keys

21. Scholes layout • Initial layout be Christopher Scholes around 1860. • Early typewriters jammed when adjacent keys were typed to fast. • Scholes design resulted from trying to avoid this occurrence. • This resulted in the famous qwerty keyboard.

22. Dvorak keyboard • An efficient keyboard for the English language, patented by August Dvorak, cousin of the composer. • Result of efforts to study typewriting behavior. • Studies in the US Navy suggest that the payback period would be 10 days from learning Dvorak. • From my own experience, doubtful.

23. The mouse • There are two-button and three button mice. • Since MS uses two buttons, three button mice are a dying species. • The third (middle) button can be emulated on two-button mice by pressing the left and the right button at the same time. • Use of the mouse is best avoided!

24. The two buttons • Primary button -- usually left • Secondary button – usually right • Actions in Microsoft windows • Left click • Right click • Left double click (time adjustable) • Left drag and drop • Right drag and drop

25. Health risks • Keyboard and mouse usage can cause serious injury. • From my experience, they are often not be the lone cause. • Others are • Stress • Bad posture

26. other devices • Replacements for a mouse are • trackballs • touchpads • joysticks • Pen-based devices • vary with respect to text recognition

27. text and code scanners • bar-code readers • magnetic ink character recognition such as on bank checks. • optical mark recognition • optical character recognition • more general form of reading characters out of handwriting or print • expensive and error-prone

28. image scanners • most widely used digitization device • you can try to run OCR once you have the image • resolution measured in dots per inch. dpi • more dpi: crisper image • fewer dpi: smaller file

29. audio input • Microphone with speech recognition software • This used to be mainly for those who can not type • But the quality has improved, and maybe we will use it for more general input. • Other analog to digital sound converters • sound cards • MIDI board

30. Other devices • sensors • biometric devices

31. http://openlib.org/home/krichel Thank you for your attention!