Lesson 1   Defining a Computer System

Hardware Overview

       The world of computing is loaded with lots of specialized, technical terms otherwise know as "computerese". As you work through this module, you will find yourself easily picking up the jargon associated with computing in general, as well as Mac jargon. To get you started, let's begin with a list of terms used to define a computer system. Becoming familiar with these terms will help you as you learn to use the computer.

Defining A Computer System

Central Processing Unit (CPU)
The CPU refers to the microprocessor chip is considered the "brain" of the computer. In this unit you have all of the circuits that make the computer system perform. The hard drive or internal hard drive is located here. Almost all of the hardware plugs into this unit. Some CPU's are combined with the monitor screen into a single unit (see the iMac on the right).

The monitor displays on-screen software applications, documents or whatever you type on the keyboard. The monitor has a power switch and brightness and contrast controls similar to the ones on television sets. Some monitor screens (the front of the monitor) are tinted to ease eyestrain for those who spend extended time working on their computer. Screens can be purchased.

The keyboard is the communication link to the computer. It is an input device consisting of an array of keys and allows the user to interface with the computer. It is very similar to the QWERTY system found on most typewriters in the United States. Some keyboards can be adapted to other key patterns.

The mouse is another input device which allows the user to interface with the computer. It is a pointing device that allows the user to merely point to what is wanted or needed on the screen, select specific windows or commands. Many of the mouse functions also have keyboard shortcuts. (Other input devices are the Trackball, Trackpad and tablet.)

An output device that can be connected to a computer. Printers come in all sorts of sizes, colors, and prices. All have different advantages. There are dot matrix printers which use an imprint from a ribbon. Another type is the ink jet printer that prints documents with ink. The laser jet is the top of the line and also the most expensive to purchase and operate. Some printers will do color work, produce various fonts, use roll paper or single sheets. Most printers come with software which must be installed onto the computer in order to use it.

Hard Disk/Drive (Internal Drive)

This is the big memory of the computer system. It is a storage device; programs and documents are stored here. The hard disk does not "blitz" with power interruption and data stored in it remains there until it is erased. Computers come with different sizes of hard drives and the size usually dictates the price range as well as how much you can store.

Floppy disk drive

Information can be put into the computer via the floppy disk drive. This information is stored on a floppy disk, a removeable storage device. Most floppy disks are 3 1/2 inches, however, some older computers have 5 1/4 inch floppies. The smaller is more contemporary and has pretty much replaced the larger. The 3 1/2" floppy disks are protected in a plastic case and are much easier to handle and care for. This does not mean that they are invincible.
Note: The new iMac does NOT come with a floppy drive.
Floppy Disks

The floppy disk is a storage device and the 3 1/2" is the most common type used in computers today. Other types of storage disks exist (Zip, Jazz, Ditto, etc.) however, require a different type of drive than the 3 1/2" floppy. Floppy disks are encased in plastic; the floppy part is the small magnetic disk inside. Disks differ in the amount of data they can store.

The amount of data is measured in kilobytes (K) and megabytes (MB or Megs). One MB is equal to 1000 K. To give you a point of reference, the average one page document is approximately 10 - 30 K, depending on the word processor and the formatting style that is used. The 3 1/2" disks that you will be working with in most Macintosh computers contain two different capacities:

  1. Double Density (DS, DD) or (2DD) - holds .8 MB (800K)
  2. Double Sided, High Density (DS, HD) or (2HD) - holds 1.4 MB (1400K)
The more common of the two is the 2HD, 1.4 MB floppy disk.

Zip disks can hold up to 100 MB and Jazz disks up to 200 MB. For more information about storage devices, see Iomega's homepage.

System Software

The Macintosh System 7 software consists of two parts: the System software and the Finder.

The System is the basic program the Macintosh uses to start itself (boot-up). The Finder creates, controls and keeps track of the Desktop (what you see on the monitor screen) and enables you to display and manage files. Both of these are stored in the System Folder and without them, the Macintosh will not operate properly.

Several of the above graphics were taken from:
Hewlet Packard Homepage
Apple/Imac Homepage
Corell Gallery software

Assignment Mac 1 - Computer Systems
  1. Practice: Identify on each of the devices listed above on the computer you are using. If you are not sure, ask your trainer for assistance.
  2. Approximately how many one page documents could you put on a 1.4 MB floppy disk? Give your site trainer the answer.

Next: Lesson 2 - Macintosh Tutorial

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