CHAPTER 1CHAPTER 1Installing and Supporting

I/O Devices

Suraya Alias

Basic PrinciplesBasic Principles I/O Device

◦ Internal – h/disk, cd drives, dvd drives◦ External – keyboard, monitor, scanner

Can be connected using ports (USB), motherboard (serial) or ports from expansion card

When supporting I/O devices, fundamental principles toremember;1. Every I/O device is controlled by software2. Refer to documentation when installing3. Some devices need application software in order to

function4. Problems with device sometimes can be solved using

driver’s update5. Learning hardware I/O is like a moving target

Working with keyboardWorking with keyboard

Ergonomic keyboard◦ Designed for safe and comfortable interactions between human

beings and machine

4 methods to connect a keyboard

1) DIN connector2) PS/2 connector (mini din)

3) USB 4) Wireless connection

Mouse and pointing devicesMouse and pointing devices

1) Mouse◦ Wireless◦ With keypad

Mouse technologies• Wheel mouse• Optical mouse

2) Trackball

3) TouchpadMethods of connecting a mouse

1) PS/2 mouse port2) Mouse bus card3) Serial port4) USB port5) Y connection6) cordless

Special Input devicesSpecial Input devices

1) Barcode reader2) Fingerprint reader

3) Iris recognition reader

Biometric device – input device that inputs biological data about a person.

Which can be used to identify a person’s Fingerprint, eyes, voice, face and handwriting.

Terms & definitionTerms & definition

Resolution = the number of individual dots of color, known as pixels, contained on a display.◦ Images are formed by series of dots and pixels◦ Resolution is expressed by identifying the number of pixels on the

horizontal axis (rows) and the number on the vertical axis (columns), such as 800x600.

◦ Resolution is affected by a number of factors, including the size of the screen.

Dot pitch = diagonal distance between two closest dots of the same color Refresh rate = how often an image is updated or redrawn on the monitor

◦ Low refresh rate will cause the image to flicker and lead to eye strain Screen size / viewable size = diagonal length of a monitor’s viewing area

(the smaller the better quality) Interlaced = refresh the monitor by painting alternate rows (odd and even)

on the screen Contrast ratio = the contrast between true black and true white color on the

screen (the higher the better)

Choosing MonitorsChoosing Monitors

Characteristics CRT LCD

Screen size Y Y

Refresh rate Y

Interlaced Y

Response Time Y

Dot pitch Y

Resolution Y Y

Pixel Pitch Y

Color Quality Y Y

Multiscan Y

Connectors Y Y

Characteristics CRT LCD

Contrast ratio Y

Viewing Angle Y

Display type Y Y

Backlighting Y

1) CRT 2) LCD

How Monitor WorksHow Monitor Works

CRT LCD CRT (Cathode Ray tube) is a

large sealed glass tube inside the monitor.

Tiny dots of phosphor material in Red, Green and Blue (RGB) combines to make up each pixel (dots of color).

Inside the CRT, an electron beam moves back and forth across the back of the screen.

This causes the dots to glow, producing an image

Also known as Flat panel displays (FPDs).

Liquid crystal display technology works by blocking light. Specifically, an LCD is made of two pieces of polarized glass (also called substrate) that contain a liquid crystal material between them.

A backlight creates light that passes through the first substrate. At the same time, electrical currents cause the liquid crystal molecules to align to allow varying levels of light to pass through to the second substrate and create the colors and images that you see.

Video cardsVideo cards A video card is rated by the bus it uses

and the amount of video RAM on the card. Both features affects the overall speed

and performance of the card

Buses used by video cards

1) VESA bus – (Video Electronics Standard Association), internal bus that was developed for faster connection between the devices and processor

2) PCI bus – (Peripheral Component Interconnect) is a local bus that was developed by Intel for better integration between of data such audio and video

3) AGP bus – (Accelerated Graphic Port) is a bus that directly access the RAM that will improve the graphic display

4) New PCI Express bus – newer bus and faster bus to replace the old AGP and PCI, used in faster CPU

Video MemoryVideo Memory

Types of video memory

1) VRAM (Video RAM)2) SGRAM (Synchronous Graphic RAM)3) WRAM (Window RAM)4) 3-D RAM (3D)5) MDRAM (Multibank DRAM)6) G-DDR (Graphic Double data rate )7) DRDRAM (Direct Rambus DRAM)

Using Ports, Expansion SlotsUsing Ports, Expansion Slots

• Most computers provide one or more USB ports, one parallel port, IEEE 1394 (Firewire) port or serial port to be used for a variety of devices

Using Ports, Expansion SlotsUsing Ports, Expansion Slots

Three types of parallel ports are ;

1. Standard Parallel Port (SPP) – old printer port (data flow in one direction

2. EPP – Enhanced Parallel Port, data flow in two direction3. ECP – Extended Capabilities Port (uses DMA – direct memory

access channel)

USB ports (Universal serial ports) is the easiest port to configure

Serial ports are sometimes configures as COM1, COM2,COM3 or COM4

Parallel ports are configures as LPT1, LPT2 or LPT3

The IEEE 1394 bus provides, 4, 6 or 9 pin connectors