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Nic Shulver, [email protected]
Input and Output Devices
IntroductionInput devicesOutput devicesInput/output devices
Contents
Nic Shulver, [email protected]
Input and Output Devices
communication between an information processing system (such as a computer)and the outside world
inputgather up and collect information enter data and instructions into the computer
Outputinformation has to be returned from the computer to the
user
Introduction
Nic Shulver, [email protected]
Input and Output DevicesExtending 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
Nic Shulver, [email protected]
Input and Output DevicesKeyboard
One of the most critical ergonomic components in the PC
Modelled after typewriter keyboardHow it works
you press keys on the keyboard,an electrical connection is made - switchthe keyboard to send a signal to the PC, telling it what key
or keys were pressed
Nic Shulver, [email protected]
Input and Output DevicesKeyboard
83-key keyboard
101-key keyboard
104-key keyboard
Nic Shulver, [email protected]
Input and Output DevicesMice
Pointing device Input spatial data to a computer Types
MechanicalOptical
ButtonsOneTwoMultiple
Connector USB PS/2 Wireless
Nic Shulver, [email protected]
Input and Output DevicesOptical 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
Nic Shulver, [email protected]
Input and Output DevicesDisplay 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
Nic Shulver, [email protected]
Input and Output DevicesDisplay 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
Nic Shulver, [email protected]
Input and Output DevicesLCD panels
LCD or “Liquid Crystal Display” screen are not the only type of flat panel displayPlasmaOrganic 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
Nic Shulver, [email protected]
Input and Output DevicesPrinters
Printers come in many types, including;Laser, colour laserInkjet and similarDot-matrix (old!)Daisy-wheel (ancient!)
Most consumers choose inkjet-type printers due to their versatility (NB ink cost)
Laser printers are common in business
Nic Shulver, [email protected]
Input and Output DevicesScanners
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
Nic Shulver, [email protected]
Input and Output DevicesConclusion
Keyboards, mice, displays, printers and scannersThere are very many different types of add-on
devices for computersThe market place changes rapidly, as we have
seenExpect USB connectivity to be popular for quite a
while (some years yet) as USB standards are constantly being upgraded
