Computer Hardware:

A computer consists of both hardware (physical parts of the computer)and software working together to help you accomplish tasks.

Hardware consists of:

• Input devices
• Processor or central processing unit (CPU)
• Memory

Input devices:

• Input devices are machines that communicate with the computer.
• Examples of input devices are the keyboard and the mouse.
• Input devices are controlled by the user.
• For example, typing on the keyboard or clicking on a mouse button.

Processor or CPU:

• CPU is short for Central Processing Unit.
• The CPU is a microchip inside the computer.
• The box that the processor resides in is commonly referred to as the CPU.
• The translation or processing of your input takes place in the CPU.
• Processing is the thinking that the computer does - the calculations, comparisons, and decisions.
• The box contains the microchip, the floppy disk drive, the CD-ROM drive, and memory.

Output devices:

• The cycle (input - processing - output) would not be possible without a holding place for the instructions and data that the processor (CPU) can easily reach.
• This holding place is known as memory.
• There are three basic types of memory:

1. RAM - Random Access Memory
2. ROM - Read Only Memory
3. Storage Devices

RAM:

• The primary memory that holds data and instructions while the computer is in use.
• Can be thought of as the memory the computer uses to obey instructions.
• Can be written to and read from.
• Important to remember that if you do not save the information in RAM to a storage device (such as a floppy disk or hard drive) before turning off the computer the information will be lost.

ROM:

• ROM is more straight forward.
• ROM is built in memory that permanently stores instructions and data.
• The instructions and data in ROM are created when it is manufactured and it cannot be changed.

Storage Devices:

A storage device is a place to store data. Although there are several types of disks, for the purposes of this tutorial, only the following types will be discussed:

• Hard Drive
• Floppy Disk
• Compact Disk/CD

Hard Drive:

• A permanent data storage device built into PCs that permits you to save and retrieve information.
• Also, stores the computer's operating system and other software.
• The size of a hard drive is usually expressed in terms of megabytes and gigabytes.

Floppy Disk:

• Floppy disks allow information to be transported easily from one computer to another.
• Floppy disks have limited storage capacity, generally 1.44 MB.
• Saving and retrieving information from a floppy disk is slower than on a hard drive.
• They are more susceptible to physical damage and viruses than the hard drive.

CD ROM:

• CD ROMs are read only storage medium.
• Typically, a CD ROM holds up to 650 MB of information.
• While information retrieval is faster than from a floppy disk, it is still not as fast as from the hard drive.

• A CD-R is highly effective for storing a large amount of data.
• CD-R can hold up to 700MB of information.
• A CD-R is a one time recordable compact disc.

CD-RW:

• A CD-RW allows you to read, write, erase and write again.
• Writing takes place in a single pass of the focused laser beam.
• This is sometimes referred to as direct overwriting and can be repeated several thousand times per disc.

Bits, Bytes, Kilobytes, Megabytes, Gigabytes:

It is important to know that the terms megabyte (MB) and gigabyte (GB) are used when referring to a computer's memory capacity. The number of megabytes or gigabytes reflects the amount of electronic holding places available for instructions or data.

• The processor only recognizes two digits: the "0" and the "1".
• All information is stored as 0's and 1's.
• The 0's and 1's are referred to as bits. (The smallest unit of information on a computer.)
• The next unit of measure is a byte which is a combination of 8 bits.
• A kilobyte is 1,024 bytes.
• A megabyte is 1,048,576 bytes
• A gigabyte is 1,073,741,824 bytes.

Software is:

• What makes the computer work.
• Software consists of an organized list of instructions that causes the computer to behave in a predetermined manner.
• For work, for play, for kids, and for adults.
• A computer game you play or a word processing program.
• Often divided into two categories: system software and application software.
• System software includes the operating system, compilers and utilities that enable the computer to function.
• Application software includes programs that perform specific tasks (e.g., games, word processors, spreadsheets, and databases).
• Figuratively speaking, application software sits on top of system software because the computer is unable to run without the operating system and system utilities.

Compiler - Program that translates source code into object code. The compiler derives its name from the way it works, looking at the entire piece of source code and collecting and reorganizing the code.

Input - where it refers to data or signals entered into a system for processing or transmission.

Keyboard - The set of typewriter-like keys that enables you to enter data into a computer. Computer keyboards are similar to electric-typewriter keyboards but contain additional keys.

Microchip - electronic equipment consisting of a small crystal of a silicon semiconductor fabricated to carry out a number of electronic functions in an integrated circuit

Mouse - A device that controls the movement of the cursor or pointer on a display screen. A mouse is a small object you can roll along a hard, flat surface.

Operating System - Operating systems perform basic tasks, such as recognizing input from the keyboard, sending output to the display screen, keeping track of files and directories on the disk, and controlling peripheral devices such as disk drives and printers.

Utilities - A program that performs a very specific task, usually related to managing system resources. Operating systems contain a number of utilities for managing disk drives, printers, and other devices.

HowStuffWorks:
http://computer.howstuffworks.com/pc.htm/printable
Provides information and pictures on how computers work.