Output devices
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The teaching part (2 min) is free to watch. A free account opens the whole lecture: 5 practice questions, 2 real past-paper questions with the answers explained, the mistakes that lose marks, the full-marks tip, a one-card summary and a quick quiz.
What this lecture covers
- From the computer to you
- What is an output device?
- The devices you must know
- LCD and LED screens
- LCD and DLP projectors
Read the transcript of the teaching part
Last time
Before we start: last time, in CPU performance, instruction sets and embedded systems, you learned these points. Here they are again on one card. Keep them in mind, because today builds on them.
From the computer to you
A computer can process millions of numbers a second, but a result that nobody can see, hear or use is worthless. It has to leave the machine. That is the job of an output device. It presents the result, or acts on the world.
What is an output device?
An output device is hardware that presents the results of processing to the user. The result can be seen, heard, printed or turned into movement. It is needed so that information the computer produces can be used. Remember the direction: with an output device, data comes out.
The devices you must know
Cambridge names these output devices. Screens: LCD and LED. Projectors: LCD and DLP. Printers: inkjet, laser and three D. And two that are not about pictures: the speaker, and the actuator.
LCD and LED screens
An LCD screen is a panel of tiny liquid crystal cells, lit from behind. The cells twist to let more or less light through, and that makes the image. An LED screen uses light-emitting diodes as its light source. LED screens use less power, are thinner and brighter, and last longer.
LCD and DLP projectors
A projector throws a large image from the computer onto a screen or a wall. An LCD projector shines a lamp through small liquid crystal panels. A DLP projector reflects light off a chip of millions of tiny mirrors. Each mirror tilts to switch its pixel on or off, many thousands of times a second.
How often it comes up
The whole chapter: Input and Output Devices.
Chapter 3.2: Output devices
- Output devices 6 min
Also for IGCSE Computer Science 0478
Which topics come up most in IGCSE Computer Science 0478 past papers, counted from every paper since 2004: Paper 1 topic frequency, Paper 2 topic frequency.