Enhancing Computer Systems: Input and Output Devices Guide

1. Contents • Introduction • Input devices • Output devices • Input/output devices

2. Introduction • communication between an information processing system (such as a computer)and the outside world • input • gather up and collect information • enter data and instructions into the computer • Output • information has to be returned from the computer to the user

3. Extending your PC • Some computers have limited external expansion capability (e.g. hand-held, laptop, SFF) • Look at the back of a PC and you can see many ports, in various shapes and sizes

4. Keyboard • One of the most critical ergonomic components in the PC • Modelled after typewriter keyboard • How it works • you press keys on the keyboard, • an electrical connection is made - switch • the keyboard to send a signal to the PC, telling it what key or keys were pressed

5. Keyboard 83-key keyboard 101-key keyboard 104-key keyboard

6. Mice • Pointing device • Input spatial data to a computer • Types • Mechanical • Optical • Buttons • One • Two • Multiple • Connector • USB • PS/2 • Wireless

7. Optical Mice • Uses camera technology and digital processing to compare and track the position of the mouse • A small LED helps to highlight slight differences in the surface underneath the mouse • Those differences are reflected back into the camera, where digital processing is used to compare the pictures and determine the speed and direction of movement • No maintenance or regular cleaning is required • Digital processing results in smoother, more accurate performance than prior technologies

8. Display devices • The CRT or “Cathode Ray Tube” was popular • but the flat panel display has made rapid inroads • CRT monitor technology advanced slowly, although the FPD has given it a push • Variable resolution in CRT displays, some claim better colour quality

9. Display devices • Critical information: • Refresh rate (60Hz, 72Hz, 85Hz on) • Resolution (800x600 through 1600x1200 and on) • Diagonal size (15-inch, 17-inch, 21-inch on) • A good modern monitor has a microprocessor controlled display with on-screen display settings • Monitors are sometimes called “SVGA” or “XGA” types - it denotes high resolution compatibility

10. LCD panels • LCD or “Liquid Crystal Display” screen are not the only type of flat panel display • Plasma • Organic light-emitting diode displays (OLEDs) • Active Matrix OLED (AMOLEDs) • Light-emitting diode display (LED) • Electroluminescent displays (ELD) • Until recently, 21-inch panels (diagonal) were considered large - the technology seems to have reached mass-market prices (consider 32-inch TV prices) • LCD screens tend to flicker much less than CRT’s but moving images may “smear”. Pixels are crisper but brightness and colour accuracy may be better with CRT displays

11. Printers • Printers come in many types, including; • Laser, colour laser • Inkjet and similar • Dot-matrix (old!) • Daisy-wheel (ancient!) • Most consumers choose inkjet-type printers due to their versatility (NB ink cost) • Laser printers are common in business

12. Scanners • Flat-bed scanners turn printed images into digital images • Until about 2001, flat-bedscanners were expensive • High spec scanners used SCSI, with lower spec scanners attached to the PC parallel port – now most are USB 2 or USB 3 and part of a multi-function printer system

13. Conclusion • Keyboards, mice, displays, printers and scanners • There are very many different types of add-on devices for computers • The market place changes rapidly, as we have seen • Expect USB connectivity to be popular for quite a while (some years yet) as USB standards are constantly being upgraded