Keyboard - the
commonest way to enter data into a computer. Each key is simply a
switch, which when pressed, results in a digital code being sent
to the computer. For example, pressing the 'A' key
produces the code 01100001 representing the lower case
letter 'a'. Holding down the shift key at the same time
produces the code 01000001 representing the upper case
Mouse - the movement
of the mouse over a flat surface is mirrored by a pointer on the
monitor screen. Under the mouse is a ball which rolls and turns
two shafts, one for each direction - left/right & up/down.
Buttons on the mouse enable selections to be made from menus,
movement of objects around the screen, and painting or drawing.
Joystick - works in
similar way to a mouse but usually used for playing action games.
The "fire" button or trigger is used to shoot at the
targets provided in the game.
Microphone - for the
input of voice in place of using the keyboard and mouse. Special
software is used to convert voice into text or to activate menu
options. This requires fast processing and a lot of memory and
will become more common as the technology improves.
light received through the lens is converted to digital signals
by sensors, rather than stored by chemical change on a film as in
a normal camera. The resulting "photograph" can then be
stored on a computer and used just like any clipart files.
enables video signals from a standard video camera or cassette
recorder to be read into a computer. The video can then be stored
as a file, displayed on screen and edited. Still images can be
captured and printed or used as clipart.
normal musical instruments which have a midi port for input into
a midi interface in the computer. The music can then be stored as
a file, displayed on screen and edited ready for playback.
Scanner - like a
photocopier it scans a full page with laser light but instead of
printing copies, it transmits the image to the computer as
digital code, which can be saved as a file. In effect, it
performs the exact opposite function to a printer by converting a
printed page into a computer file. There are also hand held
scanners which can be wiped over the page but they have to be
used very slowly and carefully for good results.
Tablet - a
flat pad which you can write or draw on with a pressure sensitive
stylus (like a pen). Movement across the pad is mirrored by
drawing on the monitor screen. Used for art work and computer
Sensor - chemical
responses to the physical environment or movement can be
converted to electrical signals in the sensor that can be
translated and used by the computer. Various sensors can be used
to measure heat, light, sound, pressure, strain, acidity (pH),
oxygen concentration, humidity, pulse, water level, water flow,
speed, tilt or simply whether something like a door or a valve is
open or shut.
emits a beam of infra red light which carries data signals.
Commonly used for input to TVs and VCRs and now becoming used by
computers as a "wireless" method of communication.
Pen - the pen
works directly on the screen. Touch sensitive screens and
electronic whiteboards that respond to the touch of a finger are
now replacing these.
Code Reader -
almost everything you buy has a bar code either on it or on its
packaging. The bar coded item is wiped over a laser scanner or a
wand is wiped over the bar code to read in the data. It is the
same as a scanner but due to the simple nature of the bar code
the scanning is very rapid. Used at supermarket checkouts and
the keys are marked with raised dots as an aid for the blind.
Keyboard - a
flatbed of contact switches covered by a flexible membrane over
which can be placed an overlay marked with whole words, pictures
or symbols. The computer is then programmed to respond
appropriately to these. Used in education as an early-learning
aid, in restaurants so the operator does not need to know the
prices, and in messy places where a normal keyboard would be at
Character Recognition (OCR) - uses an ordinary scanner to take a
photographic image of printed or even hand-written text. Special
software then looks at the image, recognises each character and
converts it into a text file. This can then be edited using a
word processor. It is also used to automatically recognise post
codes on letters at sorting offices.
Mark Reader (OMR)
- similar to a bar code reader but uses infra-red light to scan
pencil marks on prepared forms such as multiple-choice
examination answer sheets or lottery tickets.
Ink Character Recognition (MICR) - uses ink containing magnetic particles.
This method is used by banks to print on a cheque the amount that
it is made out for, then it is scanned into a computer.