what is computer

 

About desktop  computer or laptop

Speed

The computer we can assume as a great speed calculation machine. It will take out commands at a very high speed, since computer is an electronic device, all its processes can be performed in terms of microseconds and Nano seconds. A powerful CPU can calculate 3 million calculations per second i.e., a computer is accomplished of adding together two 18-digitized numbers in 300 - 400 Nano seconds.

 Microsecond = 10-⁶ seconds

 Nano second – 10 -⁹ seconds

The speed of the computer is calculated in terms of micro and Nano seconds.

Storage

Storage is nothing but memory of a computer. The memory stores the program and data and provides the information whenever central processing unit wants that. Actually the data is stored in secondary memory.  Secondary memory devices are nothing but registers, magnetic tapes. This secondary memory is also known as auxiliary memory and this will remain outside the memory of CPU. While execution, the necessary data from secondary storage devices is load into internal memory of CPU and processed.

Reliability 

Computers carry out instructions with high speed and reliability i.e., it will execute all the statements very fastly and without any errors. Computer will perform only its task. But it will never do any mistakes.

Versatility 

Computers seem capable of performing any task. Provided that the task can be reduced to series of logical steps i.e., nothing but writing a program for that task.

 Accuracy

The accuracy of computer is consistently high errors can be occurred in that but due to increased efficiency in error detecting techniques, the errors can be debugged fastly.

Automation

 A computer is much more than an adding machine. It completes application targets without manpower as we given instruction In Nano seconds. It do very fast Instead of man power completing job works.

Different types of computer.

Computers widely vary in performance, size and cost. Depending upon these factors, the computers can categorizes them into the four categories:

Microcomputers

Minicomputers

Mainframe computers

Super computers

Performance is measured in terms of speed of processing instruc­tions, storage capacity, ability to handle a large number of input and output devices and nature of operations performed (simple word process­ing to complex scientific calculations). Generally, the better the perfor­mance, the larger the size and the higher the cost.

Microcomputers 

Microcomputers are at the lowest end of the computer range. The special purposed devices that are used to control washing machines and the highly visible personal computers you see on desktops both fall under this category.

The most common applications of the PC's are word processing, spread-sheet calculating and database managing. The other applications are desktop publishing (using computers for publishing), accounting statistical analysis, graphics, investment analysis, project management etc. They are also used in teaching (the computer acts as a teacher) and entertainment is computer games. PC's support a number of I/O devices those are keyboard, mouse, joystick, printer, VDU etc.

Examples of desktop PC's are: desktops, laptops, tablets mobile phones, and Apple's Macintosh.

Minicomputers

Minicomputers perform better are larger in size and costs more than micros. Normally, they are designed to support more than one user at a time. They possess larger storage capacity and operate at higher speeds. They support faster operating peripheral devices like high speed printers which print hundreds of lines as per minute. They can also communicate with mainframes.

These computers are used when the volume of processing is large, for example, data processing for an entire organization. They are used to control and monitor production processes, to analyze results of experi­ments in laboratories, to meet instructional needs of colleges etc. They are also used as servers in Local Area Networks (LANs), Examples of mini's are: Digital equipment's PDP 11/45 and VAX 11 and PCL's Hall mark.

Mainframe computers

 Mainframes are typically more powerful than minis. They operate at very high speeds, have very large storage capacities and can support hundreds of users. They are used for data processing in large organizations where the records of thousands of employees have to be processed. They are also used to manage large centralized databases. Such databases are normally queried by hundreds of users who need to access information from different locations. They are used as controlling nodes in Wide Area Networks (WAN's). Examples of mainframes are: IBM 3000 series, Burroughs B7900 and Univac 1180.

Super computers

 Super computers are at the highest end of the computer range. They are the fastest and the most expensive machines and are considered as national resource. Although initially used for weapons design, currently they are being used for commercial purposes, like designing automobiles that will offer better protection to passengers in case of accidents. They are required and are affordable by a few organizations. These are less than 500 conventional super computers in the world. Examples: mira, trinity, param yuva-2