Output devices

1. Output devices MONITOR PRINTER MODEM (COMMUNICATION DEVICE)

2. Monitor – VDU’s • Computer monitors may be referred to as terminals, screens, displays or video display units (VDUs), but most people just call them monitors. • A colour monitor operates much like a high-resolution TV screen, and uses the same basic components. An electron gun sends out a beam that excites pixels on the screen, making them light up. Instead of an antenna to pick up a TV signal, the graphics card inside your computer generates the image sent to the electron gun in your monitor. • Each pixel on any colour monitor has three phosphors, which are red, green and blue (black is created when the phosphors are not illuminated). When the phosphors are all illuminated in different intensities they create the different colours displayed on the monitor. 

3. Ink / Bubble Jet Printers • While the technology is vastly different for inkjet and bubble jet printers, both do basically the same thing - force tiny droplets of ink out of a nozzle and onto the paper. All models made in the last five years have a very high quality capable of producing realistic photo quality • Most new Inkjet and bubble jet printers can use either black ink or colour ink cartridges. Whether you choose an Inkjet or a bubble jet printer is up to your personal preference and the size of your budget. • The speed of inkjet and bubble jet printers is measured in pages per minute (ppm). Most have variable speeds for economy printing (about 3 ppm), normal printing (about 2 ppm) and presentation quality printing (about 1 ppm).

4. Laser Printer • If you are working in an office, the printer you will most likely use is a laser printer. • Have a very high resolution, measured in dots per inch, and are excellent for printing black and white graphics and photos. • Work about the same way as a photocopier. A toner cartridge lays down drops of toner onto the paper, and then the paper passes through heated rollers, which melt the toner and fuse it onto the page. • Part of the reason laser printers are so expensive is that most have computer cards and RAM inside them which process and stores the data received from your PC. • The quality of a laser printer is measured in dots per inch (dpi), with a basic printer starting at 300 dpi. To understand this concept, picture a box exactly 1 -inch square. Using a grid, divide the box into 300 rows horizontally and 300 columns vertically, and you will have 90 000 tiny squares in the box. A 300-dpi printer can place a dot in every one of those squares.

5. Modems • Acronym for MOdulator- DEModulator. A modem is a device or program that enables a computer to transmit data over telephone lines. Computer information is stored digitally, whereas information transmitted over telephone lines is transmitted in the form of analog (SIN) waves. A modem converts between these two forms. • While the modem interfaces are standardized, a number of different protocols for formatting data to be transmitted over telephone lines exist. Most modems have built-in support for the more common protocols -- at slow data transmission speeds at least, most modems can communicate with each other. At high transmission speeds, however, the protocols are less standardized. • bps : How fast the modem can transmit and receive data. At slow rates, modems are measured in terms of baud rates. The slowest rate is 300 baud (about 25 cps). At higher speeds, modems are measured in terms of bits per second (bps). The fastest modems run at 57,600 bps, although they can achieve even higher data transfer rates by compressing the data