The Hardware

Computer hardware is made up of the equipment that makes up your computer unit.

These parts include your monitor, central processing unit (CPU), keyboard, mouse, printer, and modem.
It is possible to add other peripherals to this basic configuration, but most computers operate with just the basic configuration.

The computer is an electronic machine that performs the following four general operations:

Input
Storage
Processing
Output.

Input

The input hardware allows you to enter data into the computer. The primary devices used are the keyboard and mouse.

Keyboard - The keyboard looks like the typewriter. A numeric keypad is located to the right of the keyboard. Numeric keys have the same placement as a 10-key calculator, which allow the operator to enter data rapidly.

Mouse - The mouse is a device that allows you to control the movement of the insertion point on the screen. The operator places the palm of the hand over the mouse and moves it across a mouse pad, which provides traction for the rolling ball inside the device. Movement of the ball determines the location of the I beam on the computer screen. When the operator clicks the mouse the I beam becomes an insertion point which indicates the area you are working on the screen. You can also click the mouse and activate icons or drag to move objects and select text. There are other input devices, such as touch screen, joystick, modem, scanner, and voice recognition systems. The mouse rests on a pad on the table next to your computer and has a curved body with an arched back to help it fit comfortably into your right hand. Rest your right hand on the mouse now. Hold the mouse and move it around on its pad, but keep on watching the computer screen. As you move the mouse, you will notice a white arrow/vertical black line moving around the computer screen. The movement of the mouse controls the movement of the arrow/line on the screen. Continue to move the mouse around with your hand some more until you feel comfortable with the connection between your hand movement and the changing position of the arrow/line on the computer screen.

Processing
The central processing unit or (CPU) is the "brain" of your computer. It contains the electronic circuits that cause the computer to follow instructions from ROM (read only memory) or from a program in RAM (random access memory). By following these instructions information is processed. The CPU contains three parts.

1. Arithmetic Logic Unit - ALU is where the "intelligence" of the computer is located. It can add and compare numbers. To multiply 2 x 4 the computer would add 2 + 2 + 2 + 2. The ALU makes decisions by determining if a number is greater, less, or equal to the other number. Processing is completed in nanoseconds, which is a billionth of a second.

2. Memory - Two types of memory contained on a chip are RAM (Random Access Memory) or ROM (Read Only Memory). ROM memory has been installed on your computer by the manufacturer and can not be altered. ROM is the memory that determines all the basic functions of the operation of your machine, such as startup, shut down, and placing a character on the screen. RAM is temporary memory, which displays the information you are working on. RAM remembers what you see on your screen while you are working. Today's applications required large amounts of temporary memory, which may require you to upgrade and add more RAM memory.

3. Control Unit - This is the part of the unit, which directs information to the proper places in your computer, such as calculation of information by the ALU unit or to store and print material.

Output
Output devices such as a monitor or printer make information you input available for you to view or use.

A monitor's front is called a screen with a cathode ray tube (CRT) attached to the screen. Portable computers use a (LCD) liquid crystal display. Today's super video graphics array (SVGA) monitors display 256 sharp and clear colors.

Printers used with computers fall into two categories, impact or nonimpact. Impact printers, such as dot matrix print by contact against a ribbon making imprint on paper. Inkjet printers print images by not touching the paper. Ink jet printers spray ink onto the page while a laser printer works like a copying machine. Laser printers print a higher quality product but might be more expensive than other types of printers.

Storage
Auxiliary storage devices, also called secondary storage devices, are used to store instructions and data when they are not being used in memory. Two types of auxiliary storage more often used on personal computers are floppy disks and hard disks. Also, CD-ROM drives are common.

Floppy Disks - A floppy disk is a circular piece of oxide-coated plastic that stores data as magnetic spots. Personal computers most commonly use floppy disks that are 3 ½ inches in diameter.

To read data stored one floppy disk or to store data on a floppy disk, you insert the floppy disk in a disk drive. If the disk is unused, you must format or initialize it before your computer will allow you to store data on it. Formatting organizes the tracks around the disk into pie like slices called sectors which make it possible for your computer to save and retrieve information. The density of the bits on the track and number of tracks on a disk determine the number of characters that can be stored.

Floppy disks are identified as being double density or high density. Most machines purchased after 1993 will use a high-density disk. A machine that has a double density drive can't process a high-density disk. Note the chart below for disk information.

Floppy Disk Capacity
Description Bytes
5 ¼ inch disk
Double-sided, double-density 360 KB
Double-sided, high-density 1.2MB
3 ½ inch disk
Double-sided, double-density 720 KB
Double-sided, high-density 1.4 MB
1.4 MB is equal to 500 pages of text.

Floppy disks must be handled with care to preserve data. Follow the suggestions to protect your floppy disk.

1. Store in box or disk storage container.
2. Protect disk from dust.
3. Keep disk out of sunlight and away from extremes of hot or cold.
4. Don't press hard when writing on labels. Use a felt tip pen.
5. Insert metal side into drive first with the hub of the disk down.
6. Don't store disk near magnetic sources.

Hard Drive - Much like a floppy, the hard disk located inside the computer case is made of a stack of rotating disks, called platters. Data is recorded on a series of tracks that have been divided into sectors. Most computers have one hard drive, located inside the computer case. If a computer has one hard drive, it is called drive C. If a computer has additional hard drives, they are called drives D, E, and so on. A hard drive stores your programs. When you buy a new program, you must install the program files to your hard drive before you can use the program. A hard drive stores your data files such as documents spreadsheets, and graphics.

CD-ROM Storage - Since each CD-ROM can store 600 million bytes of data or 300,000 pages of text, they are today's answer to make you computer feel like a machine twice its size. Because of its external storage, you can use your machine to access an encyclopedia, games, graphics, and a variety of sources that use large amounts of memory.

DvD's are storage devices that are available with a number of capacities ranging from 4.7GB to 17GB.

Memory Sticks. These handy little gadgets provide flexible storage and also come in a variety of storage capacities.