Model of computer

ON THE BASIS OF MODEL
1. XT Computer
XT stands for extended or extra Technology. It is the old text based system with no GVI (Graphic User Interface). It supports only commands given in the form of text. So it is called CLI (Command Line Interface). Input and Output device was not so flexible and is slower than present device. Processor Like Intel 8080, 8086, 8088, etc. used this technology.

2. AT Computer
AT stands for Advanced Technology. AT computer is fast and run GUI based and CLI based on Operating System. Input and output are interactive flexible and faster. Processor like Intel, 80286, 80386, 80486, Pentium I, II used AT.

3. PS/2 Computer
PS/2 stands for Personal Computer System 2. It is a upgraded version of AT Computer with increased speed and performance. It is used in Laptop Computer having rechargeable and battery operated system along with faster and flexible input, Output device.

Vacuum Tube

Vacuum Tube
The Vacuum tube was invented by Lee De Forest in 1907. The Vacuum tube was used in the First Generation of computer. It is more electric power consuming and delicate because more electric power is needed to heat filament. The diode has cathode and anode filled in vacuum tube. Triode has an evacuated glass tube with three electrodes anode, cathode and grid. The grid is applied to control current. The main application of vacuum tube was to raise the strength of a weak signal and thus acts as an amplifier.

IC of computer

Integraed Circuit (IC)

IC is a subject of micro electronics in which very small components are designed for several purpose.An IC is one in which circuit components such transistor,diodes,registors,apacitors etc are mounted(kept).The invention of IC chip had changed communication system data processing technique,space exploration,satelliate,medicine and other machine controlled industrial units.Typical chip is rectangular or square in shape with size of 1 cm square or smaller and contains millions of inter connected elements.
Advantages Of IC

1. IC increased reliability due to lesser number of connections among the components. 2.Extremely small in size,lesser weight low power comsumption and less cost.
Types of Ic

1. SSI(Small Scale Integration) 100 electronic elements on small chip.

2. MSI(medium Scale Integration) 100 to 3000 components on a small chip.

3. LSI(large Scale Integration) more than 3000 components on a small chip.

4. VLSI(Very large Scale Integration) 100000 to 1000000 components on a small chip.

5. ULSI(Ultra large Scale Integration) millions of transistors on a small chip.

6. WSI(wafer Scale Integration).

7. SOC(System On Chip).

Qualities of the Computer

Characteristics of the Computer
1. Speed:
The speed of electronic computer is very fast because the signal can pass at the speed of electricity which is near to that speed of light Pe 2.997x108 m/sec. Thus millions of the calculation can be done in a second. Such speed are beyond the comprehension of human brain.

2. Accuracy
The accuracy of computer is consistently high and every calculation is performed with the same accuracy i.e. Almost 100% accurate result are same as per design.

3. Diligence
Computer can perform repetitive task without being bore. Diligence means being constant and earnest in effort and application. It can continuously work for several hours and day after the data and programs are fields in it.

4. Storage
A computer can storage great amount of data. It has data storage area called Memory. Any data stored in memory can be retrieve at any time and at very fast speed.

5. Automatic
Computer is an automatic machine, capable of functioning, automatically, once the appropriate set of instruction and data are provided to the computer.

6. Reliability
Computer System is particularly adept a lot of work without any mistake and tiredness. That's why they are widely used everywhere because of their reliability.

7. Versatility
Computer can perform different tasks depending upon different program fed to it, is known as Versatility. It has wide range of applications areas i.e. it can do many types of jobs. It can perform operations managing from simple mathematical calculation to highly computer and logical multiplication. Some of the applications areas of computer are education, business, technology, banks, etc. So, it is Versatility in nature

8. Word Length
Digital Computer operates one binary digits(bit) combination of 1(one or high) and 0(zero or low) which means all data or information are kept in computer in terms of 0's and 1's. 8 bit is equal to 1 byte. The number of bits that a computer can process

Types of Operating System

Types of Operating System
An operating system is organized collection of programes(software) that control the averall operation of the computer system.There are different types of operating system,which are described below:

1.Single User Operating System
Single User Operating system is a type of operating system that provides an environment where single user can work at a time.All the resources of the system are available to the user. MSDOS is a good example of single user operating system.

2.Multi User Operating System
A multi user operating system is a kind of operating system that provides an environment where multiple user(no. of user) can work at a time.These system divides the total into number of time slics and schedule the task one after another in the given priority.Unix and Windows NT are some example of multi-user operating system.

3.Multi-tasking Operating System
A multi-tasking operating system is an operating system that allows a computer to execute(run) one or more than one task or jobs at a time.Windows 95/98 is good example of multi-tasking operating system.

4.Real time operating system
Real time operating system are online system that response to input immediately.These operating system are design for the purpose of controlling and monitoring the extra activities with timing constant.Some example of Real time operating system are CCP, BLMX etc.

Computer Software

Computer Software
The term 'software' means a collection of programmes. A programe is a set of instruction that is required to accomplish of a particular task.
The program which makes computer work is called Software.

Types of Software
There are many software available.Every software has been made specifiec to its task,According to the performance,the software can be catagories into two types:
1.Application software
2.System software

Application software
It is a collection of application programmes.An application programmes perform specific job for the users for e.g:result processing,financial accounting,ticket reservation etc.Application software can be standardilized to be used by anyone which is packaged software,An Application software can be classified as follows:

a.Tailored softaware
Taiored software are those software that are epecially designed and developed to solve a specific job.For e.g:processing and printing HSEB results.

b.Packaged software
Packaed software are those software which are designed and developed for the grneral purpose.For e.g:word processing software(MSWORD).

On the basis of brand of computer

On the basis of brand
On the basis of brand , the computer can be classified as IBM PC, IBM compatibles and Apple/Macintosh computer.

1.IBM PC
IBM PC is the largest computer manufacturing company establishing USA. The computer manufacture by IBM PC or branded computer.Personal Computer(PC) is the most important type of micro computer system. The micro computer manufacture by IBM company are called IBM PC.These computers are reliable,durable and have better quality but they are costly.

2)IBM compartibles
The computers that have some functional characteristics and principles of IBM computer are called IBM compatibles. In other word, all the computer are manufactured by the another companies rather than IBM company are Known as IBM compatibles. All the software and hardware of IBM compartibles. These are cheaper and Their Parts are easily available in Market.they are also duplicate or assemble computer.

3)Apple/Macintosh Computer
All the computers manufacture by apple cooperation, a leading computers manufacturing computer of USA are known as apple/macintosh computers. These computer use their own software and hardware . The are totally different than that of IBM computers, In terms of both hardware and software. For e.g software developed for apple computer can't run or IBM computers and vice-versa. Similarly, floppy disk formatting in IBM computer can't be recognized by apple macintosh computer and vice-versa. It are popularly used in desktop publishing (DTP) houses as they provide better quality of graphic output.