OUTPUT DEVICES

An output device is a peripheral device that allows a computer to communicate information to humans or another machine by accepting data from the computer and transforming them into two categories.
(i)                 Output that can be readily understood and used by humans.
(ii)               Output to secondary storage devices that hold the data to be used as input for further processing by computer.
Output that can be understood by humans can be in the form of hard copy or soft copy.
HARD COPY
It is output on paper and can be read immediately or stored and read later. This is a relatively stable and permanent form of output.
SOFT COPY
It is usually a screen – displayed output. It is a transient form of output and is lost when the computer is turned off.
Devices confirming to above specifications are classified as follow:
(A) Soft copy
(i) Virtual; graphic card, VDU (Visual Display Unit)/ Monitor, projector etc.
(ii) Sound; sound card, speaker, computer speech synthesis etc.
(B)  Hard copy
(i) Printer; impact printers etc.
(ii) Daisy wheel printers; non – impact printer.
(iii)             Plotter.
SOFT COPY DEVICES
An output on soft copy devices enables viewing of the work that allows corrections or rearrangement of material to suit specific needs. It also includes the device for voice and sound output, the speaker. The most commonly used soft copy device is a monitor.
VISUAL DISPLAY UNIT (MONITOR)
A computer display unit (also known as a computer monitor, computer screen or computer video display) is a device that can display signals generated by a computer as images on a screen.
Monitor is another term for display screen. The term, ‘monitor’ however usually refers to the entire box, whereas display screen can mean just the screen. In addition, the term monitor often implies graphic capabilities.
FUNCTIONS OF MONITOR
A computer monitor    displays information processed by the computer’s video card. When video card or graphic card converts binary information from 1s and 0s into images, these images are displayed on the directly connected monitor. It is either Cathode Ray Tube (CRT) or liquid crystal displays (LCD). Monitors have display functions that include powering it on and off, controlling brightness, contrast and position among others.
TYPES OF MONITORS
There are many ways to classify monitors. The most basic is in term of colour capabilities which separates monitors into three classes:
(a) MONOCHROME: It actually displays two colours, one for the background and other for the foreground. The colours can be black and white, green and black, or amber and black.
(b) GRAY SCALE: It is a special type of monochrome monitor capable of displaying different shapes of gray.

(c) COLOUR: It can display 16 to over 1 million different colours. Colour monitors are sometimes called RGB monitors because they accept three separate signals; red, green and blue.
SPEAKERS
Computer speakers or multimedia speakers are external speakers and are usually equipped with a male – end phono plug to computer sound cards; and some people link computer sound card to nearby stereo systems. There are also USB speakers which gain their power from 5 volts of a USB port. Computer speakers are usually a simplified stereo system without a radio or other media sources built in.
Computer speakers range widely in quality and in price. Typically, the simplest computer speakers come with computer.
PC SPEAKER
It is the most primitive sound system used in IBM compatible PCs and in fact used to be the only one in use in PC games before more technologically advanced sound cards.
SPEECH SYNTHESIS
Speech synthesis is the artificial production of human speech. A system used for this purpose is termed a speech synthesizer and can be implemented in software or hardware. Speech synthesis systems are often called text – to – speech (TTS) system in reference to their ability to convert text to speech.
REFRESHABLE BRAILLE DISPLAY

A refreshable Braille display is an electro – mechanical device for displaying Braille characters. The display usually sits under the computer keyboard. It is used to present text to computer users who are blind.
HARD COPY DEVICE
A hard copy device is a printed copy of information from a computer.


PRINTER
A printer produces output usually in the form of text on paper.
TYPES OF PRINTER
Impact printer: it is one that generally operates by using a hammer to strike a character against an inked ribbon. The impact printer then causes an image of the character to be printed.
An impact printer functions just as typewriters do. Their main disadvantage is that they are relatively slow, noisy and subjected to mechanical breakdown. Examples are Dot matrix, character printer etc.
Non – impact printers: They were recently developed to meet some of the needs that were not being satisfied by impact technology. Most high – speed page printers use some form of non – impact device, but high speed are not the only benefit of non – impact technology. Examples are; Laser, Thermal, Inkjet etc.
Plotter: This is a vector graphics printing device that connects to a computer. Plotters print their output by moving a pen across the surface of piece of paper.


Comments

Post a Comment

Popular posts from this blog

COMPUTING DEVICE (PRE – COMPUTER AGE TO 19TH CENTURY)

Image
(i)                   ABACUS: This is the first calculating device invented by Chinese. It is made up of a frame divided into two parts by a horizontal bar an vertical threads. It is also known Soroban in Japan and Suan Pan in China. It is used for adding and subtracting numbers. (ii)                 JOHN NAPIER BONE: In 1917, Scotsman named John Napier invented logarithm which are a technology that allows multiplication. It consists of a set of eleven rods, with four sides each used as a multiplication tool. These rods were made with bones. (iii)               SLIDE RULE: Napier’s invention led directly to slide rule. It was first built in England in 1632. It uses two logarithm scales to allow rapid multiplication and    division of numbers. (iv)               PASCAL’S CALCULATOR: In 1642, Blaise Pascal, a French mathematician and scientist at age 19 invented the PASCALINE which is the first mechanical calculating machine. It is used for addition and subt
Read more

COMPUTING DEVICE (20TH CENTURY TO COMPUTER AGE)

Image
HARVARD MARK I In 1937, Howard A. Aiken of Harvard University, using the techniques already developed for punched card machinery, began work on the design of a fully automatic machine in collaboration with International Business Machines Corporation. His aim was to develop a machine that could help him in the solution of difficult differential equations, the large calculation of which would have been unreal manually. COMPONENTS The Mark I was originally controlled from pre – punched paper tape without provision for reversal, so that automatic transfer of control instructions could not be programmed. Output was by card punch and electric typewriter. USES Harvard Mark I, handled 23 – decimal – place numbers (words) and could perform all four arithmetic operations; moreover, it had special built – in programs or sub routine to handle logarithms and trigonometric functions. ENIAC ENIAC used a word of 10 decimal digits instead of binary ones like previous automated calcula
Read more

INFORMATION AND DATA

DATA AND INFORMATION Data is derived from the Latin word called DATUM which means “fact that is yet to be manipulated to produce result. Therefore, data is a raw fact, event, transaction or activities that have not been processed. Examples are 1, k4, Olu etc. TYPES OF DATA (i)                  ALPHABETIC DATA: This is a data that have relationship with alphabets A – Z. Examples are sex, name, State of origin etc. (ii)                NUMERIC DATA: These are data that made up of numbers or digits value only. Examples are number of students in a class, number of children in a family, age etc. (iii)              SYMBLOIC DATA: These are data that represents symbolic values. Examples are - , +, x ,/, % etc. (iv)              ALPHANUMERIC DATA: These are data that combines alphabetic and numeric data. Examples are date of birth, address, Peugot 407, Ak 47, SS1 etc. SOURCES OF DATA (i)                  Library. (ii)                Past records. (iii)              Inte
Read more