By Andy Walker
Let's go over what you'll see outside your computer. These are known as
"peripherals" and are normally connect by cables.
Display
This is the television-like screen where the results of a computer's tasks are displayed. Displays (or monitors)
come in all sizes, but most commonly they are either
15 or 17 inches (measured diagonally from one corner of the screen to the opposite
corner). The monitors with bulbous back ends are sometimes called CRTs, which is short
for Cathode Ray Tube. This refers to the technology inside the monitor. Some newer
monitors are flat. These are called flat-panel or TFT (thin film transfer)
displays.
Mouse
A mouse is a device that is used to control the computer. It is normally a teardrop
shaped gadget with buttons at one end. A cable connects the mouse to a computer. When
the mouse is moved on a pad, called a mousepad, the cursor on the screen moves. A
cursor is a small symbol displayed on the computer screen (normally a diagonal arrow
that is used as a pointer) that shows you what the mouse is referencing on the screen.
When a computer performs specialty tasks, the cursor changes into a different symbol to
represent that a computer program is in a special mode. For example, when you are
editing text, the cursor is a vertical line that shows where you are in the
text.
Keyboard
A computer keyboard contains all the letters of the alphabet and numbers one through
nine. It operates like a typewriter keypad, but instead of moving an arm, which strikes
the paper, it sends an electronic impulse to the computer, which displays a character
on the monitor.
Floppy Drive
A floppy drive is a part of the computer that can read and record onto a special
disk, referred to as a "floppy disk". The actually drive is a little bigger than half a
piece of bread, but you will only see it as a slit in the front of the computer. This
slit is where the floppy disk is inserted. The actual "floppy disk" is inside a
3.5-inch square plastic covering. Floppy disks, which are magnetic, can contain about
1.44 megabytes of data, which is enough space for perhaps all the works of Shakespeare,
but in the computer world this is not very large. It is used to store information
outside the computer or to move data files between computers.
CD-ROM Drive
A CD-ROM is a computer drive that reads Compact Disks similar to the ones you can
play on a stereo. CD-ROM means "Compact Disk - Read Only Memory". A CD-ROM drive can
read either audio Compact Disks (CDs) or data Compact Disks. Data Compact Disks can
contain computer programs and data. This information is recorded as tiny pits on the
surface of the CD. A laser is used to read these pits and converts these into ones and
zeros (binary information), which is used by the computer. Normally when you buy a
program from a computer store, it comes on a CD.
Printer
A printer is designed to output information from a computer onto a piece of paper.
There are three kinds of printers: dot matrix, laser, and inkjet.
- Dot-matrix printers put ink on paper by hammering tiny pins against an ink
ribbon. These are rarely used any more, though sometimes you'll still see them in
banks, printing information on long rolls of paper. They are also good for printing on
forms.
- A laser printer uses a laser beam to change the electrical charge on a
cylinder called a "drum". The drum is then rolled through a powder (called "toner"). It
picks up toner on the charged portions of the drum (kind of like the way static
electricity can make dog hair cling to clothes). The drum then transfers the toner to
paper using heat and pressure. Laser printers can print black or colour pages, though
the colour ones are expensive.
- An inkjet is the most inexpensive type of printer you can buy. It can create
colour or black output. It works by super heating liquid ink and forcing it through
tiny holes. This results in tiny ink droplets being sprayed onto the paper to create an
image.
Scanner
A scanner is a device used to copy an image off paper and convert it into a digital
image, which can be saved as a computer file and stored on a hard drive. Scanners can
use a special kind of technology called Optical Character Recognition (OCR) available
in some computer programs to read text from paper and save it as an editable document
file.
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