What’s connected to a computer? All about peripherals

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.