COMPUTER BASICS

Computers are playing a very important role in how individuals work as well as how they live. Almost every organization has computers to help them operate more efficiently. Individuals also use computers at home for educational, entertainment, and business purposes. This paper tries to teach the basics about computers, the different categories of computers, hardware and software, and maintaining your computer. It also teaches about computer applications in education and explore various technology issues that are related to computers such as ethice, privacy and security.


Personal computers

Personal computers are desktop computers designed for an individual's use. They run programs designed to help individuals accomplish their work more productively.

Servers

Servers are not designed to be used directly. They make programs and data available for people hooked up to a computer network, a collection of computers connected together so that they can exchange data.

Minicomputers

Minicomputers are multi-user systems that can handle the computing needs of a smaller corporation or organization. Many people use them simultaneously by means of remote terminals or personal computers.

Personal computers

Mainframes are huge, multi-user systems designed to handle gigantic processing jobs in large corporations or government agencies.


Supercomputers
Supercomputers are ultra fast computers designed to process hugh amounts of scientific data then display the underlying patterns that have been discovered.

Input Devices

An input device allows you communicate with a computer. You use input devices to enter information and issue commands. Input devices include keyboard, mouse, scanner, digital camera, touch pads and joystick

Output Devices

Some Common Output Devices:

Monitors and Display Shows the processed information on a screen
A monitor uses a Picture Tube like a television with the image displayed on the front of the tube, which is called the screen.

Displays are flat and use plasma, LCD, active-matrix, or some other technology.
Monitors used to be called Cathode Ray Tubes (CRTs) because of the picture tube, which is a large vacuum tube.

Storage Devices

Storing information ON the Computer
The computer stores information as a string of zeros (0) and ones (1)
The standard string length is eight 0's or 1's in a row
This standard length is called a byte
A byte equals one character
A character is a letter, number, or symbol - it is about any thing that can be typed on a keyboard
There are 256 standard characters used by almost all computers
Information size measurements
Kilobyte (KB)
One kilobyte equals about 1024 bytes
1KB is about 140 words, about a half page of typed double-spaced text (words only)
Megabyte (MB)
One megabyte equals about 1000 KB
One megabyte equals about 1,000,000 bytes
One megabyte equals about 500 pages of text, or one large book
Gigabyte (GB)
One gigabyte equals about 1000 MB
One gigabyte equals about 1,000,000 KB
One gigabyte equals about 1,000,000,000 bytes
One gigabyte equals over 1,000 books of text
Some Common Storage Devices
Hard Drive
The hard drive is the primary device that a computer uses to store information. The hard drive stores programs, data files, saves files, and organizes files. The hard drive is located inside the computer case. The hard drive, magnetically stores data on stacks of rotating disks called platters.
Floppy Drive
The floppy drive stores and retrieves information on a floppy disk.
CD -ROM Drive
CD-ROM is a device that reads information stored on a compact disc. CD-ROM stands for Compact Disc Read Only Memory. One CD is equal to the space in over 40 floppy disc.

Removable Hard Disk
A zip disk is a removable disk that holds a large amount of information. A zip disk can be used to achieve, protect and transfer large amounts of data.
Zip Drive & Zip Disk
A computer system unit contains many parts.
Motherboard - The motherboard is the main circuit board of a microcomputer. It is also known as the mainboard or system board.
CPU - The CPU is the central electronic chip that determines the processing power of the computer.
Memory - Memory is the part of the computer that temporarily stores applications, documents, and stem operating information.
Bus - A bus is an electronic line that allows 1s and 0s to move from one place to another.
Expansion Slots - Expansions slots appear on the motherboard. They are sockets into which adapters are connected.
Ports and Connectors - A port is a connector located on the motherboard or on a separate adapter.
Bays - A bay is a space inside the computer case where a hard drive, floppy drive or CD-ROM drive sits
Power Supply - A power supply changes normal household electricity into electricity that a computer can use. Sound Components - A sound card lets a computer play and record high quality sound.

Central Processing Unit (CPU)
Does all of the work for the computer
Does all of the mathematics, mainly addition
Does all the logical comparisons of values
Directs the flow of data in a computer
Controls the operation of the parts of the computer
Today, all CPUs are microprocessors
A microprocessor is a complete computer on a silicon chip
A microprocessor does all of the functions of a computer
stores data and instructions waiting to be used
follows changeable instructions
does input, processing, and output
CPUs have three basic parts
The Arithmetic Logic Unit (ALU)
does all of the mathematics in a computer
does all of the logic comparisons of values
some common logic comparison symbols
= equal to
<> greater than
<= less than or equal to >= greater than or equal to
<> not equal
The Control Unit
directs the flow of information into the CPU and/or memory or storage
controls which instructions the CPU will do next
Registers
Used to store data and instructions inside the processor
Size of the registers can affect the speed and performance of the processor
Speed of CPUs
The speed of CPUs is measured in hertzs.
A hertz is on cycle per second.
Need to measure time to determine cycles per second
All computers have a clock built into them for timing the cycles
The clock is usually located in a small metal box on the motherboard.
Today, many CPUs can complete over six (6) instructions per second.
Speeds of modern CPUs
Most computers have a CPU that can do more than 400 MHz.
MHz stands for megahertzs
A MHz is 1,000,000 cycles per second.
Computers will soon be at speeds of over a gigahertz, 1,000,000,000 Hertzs.
Memory
Primary memory can be used directly by the CPU
Consists of silicon chips, usually either VLS or VLSI technology is used to create the chips
Two forms of Primary Memory
Read Only Memory (ROM)
Random Access Memory (RAM)
Primary memory is also called primary storage
Read Only Memory (ROM)
Stores instructions that are used by the CPU
Tells the CPU how to be the kind of computer it is, for example a Windows, Macintosh, or Play Station computers.
Tells the CPU how to work with the different parts of the computer
ROM can also hold programs that are directly accessed by the CPU. One such program is the self-test when the computer is first turned on. The self-test tests to seem if all the parts on the main circuit board (mother board) are working correctly.
The instructions in ROM can not usually be changed
The instructions are built into the electronic circuits of the chips
These instructions in ROM are called firmware
To change the instructions in ROM you need to usually change the chips or do some other special process that is normally not available to an average user.
The instructions in ROM are nonvolatile. They stay in ROM even when the computer is turned off.
Access to information is random access.
Random access means that any piece of information in ROM can be accessed at any given time without access other information first. It is a lot like the tracks on a music CD. You can access any track at any time and in any order.
The other kind of access is sequential access. You must access the information in the order that they are located. This is a lot like a music tape. You must play the songs in order, or you have to fast forward past songs to get to the one you want.
Random Access Memory (RAM)
Store data and instructions that are used by the CPU to perform some task.
These instructions are usually loaded into RAM from a secondary storage device.
RAM is also used to store instructions that tell the CPU how to work with its parts. These instructions are usually called drivers.
The instructions in RAM are constantly changing, depending on the needs of the CPU.
The instructions in RAM are volatile.
When the computer is turned off the information in RAM disappears.
The information in RAM needs to be saved to secondary storage before the computer is turned off.
Access to information is random access.
Communications Devices
Specific equipment and programs are needed to connect to the Internet or to communicate with other computers. You can use any type of computer such as IBM compatible or Macintosh to connect to the Internet or communicate with other computers. You need special programs to use the Internet. Most companies that connect you to the Internet provide the programs you need free of charge. You also need a modem to connect to the Internet. A modem translates computer information into a form that can be transmitted over telephone lines. Modems can be used to connect you to the Internet, exchange information, and to send and receive faxes.