INTRODUCTION TO PC

1. Introduction to the PC

 A computer is a device or set of devices which work under the control stored program (which can be changed ), automatically accepting and processing data to produce information.

Mainframes:

Are the very largest computers - million dollar machines, which can occupy more than one room, An  example is IBM model 390.

 

Minicomputers:

Are large powerful machines. They typically serve a network of simple terminals. IBM's AS/400 is an example of a minicomputer.

Workstations:

Are powerful user machines. They have the power to handle complex engineering applications. They use the UNIX or sometimes the NT operating system. Workstations can be equipped with powerful RISC processors like Digital Alpha or MIPS.

PC's:

Are the Benjamin's in this order: Small inexpensive, mass produced computers. They work on DOS, Windows, or similar operating systems. They are used for standard applications.

(i) COMPUTER SYSTEM COMPONENT

·         Input devices

·         Central Processing unit (CPU)

·         Output devices

·         Secondary storage

Central processor unit: consisting of two component

-The arithmetic Logic unit  (ALU)

-Control Unit (CU)

Its consists

·         a microprocessor which is a single microchip directly to the motherboard, which is the main electronic board in the microcomputer

2. How computers work

The operating system (OS) is the software that controls functionality and provides lower-level routines for application programs. Most operating systems provide functions to read and write data to files. An operating system translates requests for operations on files into operations that the disk controller can perform. The operating system helps the computer perform four basic operations, :

The input operation

The processing operation

The output operation

The storage operation |

The most common way to input data into a computer is with a keyboard and mouse. Another way to input data is with a touch screen. On full screen computers, touch screens have on-screen buttons that can be accessed with a finger or a stylus. These applications are custom-designed and typically simple to use. Therefore, these applications can be used by anyone. Touch screens are also used on PDAs and tablet computers. Because of the smaller screens, a stylus is required for precise interaction with screen objects. Input devices allow the user to open a Web page, send an e-mail file, or access a file from a network server.

After the data has been entered, the computer can process the data. While a file is open and the text is being reformatted, the computer is processing data.

Processing data usually results in output. Examples of output include a word processor file or a spreadsheet. The most common way to output data is to send the data to the computer monitor, or to a printer. Most computers have a connection to the Internet. Other ways to output the data includes sending the data to the Internet using e-mail or through a web page.

Data storage is probably the most important of the four basic computer functions. Floppy disks and hard drives are examples of storage devices. The most common way to store a file is to save it to a hard drive. Hard drives can be compared to large file cabinets. An operating system will find a place on the hard drive, save the file, and remember the location of the file.