TYPES OF COMPUTER

Fig. 1. Types of Computers

We have three types of computer. These are

    1.    Digital Computer    2. Analog Computers        3. Hybrid Computer

                  

1. DIGITAL COMPUTERS:-

  
 The digital computers works upon discontinuous data. They convert the data into digits (binary digits 0 and 1) and all operations are carried out on these digits at extremely fast rates. Digital computers are much faster than analog computers and far more accurate. Computers used for business and scientific applications are digital computers. Digital computers can further be classified in two ways :

    (a) Purpose wise digital computers are classified into two types:-

(i)         SPECIAL PURPOSE COMPUTER :- it is the one that is designed to perform a specific task. The instructions (programs) to carry out the task are permanently stored in the machine. For the specific tasks, this type of computer works efficiently but such computers are not versatile.

Fig. 2 specific purpose computer

(ii)              GENERAL-PURPOSE COMPUTERS:- It is the one that can work on different types of programs input to it and thus be used in countries applications. The programs are not permanently stored but are input at the time of execution. These computers are very versatile.

fig.3 General purpose computer

(b)  SIZE AND PERFORMANCE WISE DIGITAL COMPUTERS:- it can be classified into two categories :

(i)              EMBEDDED COMPUTERS:- computers exist in a wide range of sizez and power. The smallest are embedded within the circuitry of appliance such as televisions, washing machines and wrist watches. These computer are typically preprogrammed for a specific task such as tuning to a particular television frequency or keeping accurate time.

Fig. 4 Embedded Computer

(ii)              MICROCOMPUTER:- A microcomputer is a computer whose CPU is a microprocessor. A microprocessor is a processor whose all components are on a single integrated circuit chip. Those are normally single-microprocessor, single-user systems designed for performing basic operations like educational, training, small business applications etc.

Three major categories of microcomputers :-

(a)  PDAs OR PROGRAMMABLE COMPUTERS :- Programmable computers may vary in their computational power, speed, memory and physical size. The smallest of these computers can be held in one hand and are called Personal Digital Assitants (PDAs). 

Fig.5. Programmable Computer

 (b)LAPTOP (NOTEBOOK) COMUTERS AND DESKTOP PERSONAL COMPUTERS :- these  are typically used in businesses and at home to communicate on computer networks for word processing to track finances and to play games. They have large amount of internal memory to store hundreds of programs and documents. They are equipped with a keyword; a mouse, track ball and other pointing devices. Laptop computers usually have similar hardware and software as PCs but they are more compact have flat, lightweight LCDs instead of video display monitor. Laptop computers can be carried out in brief cases. Laptop computer are so called as they can sit on  a lap and desktop computer are  so called as they can sit on a desk.

Fig.6. Laptop

 (c)   WORKSTATION:- workstations are similar to personal computers but have greater memory and more extensive mathematical abilities and they are connected to other workstations or personal computers to exchange data.

Fig.7. Workstation

(iii)     MINICOMPUTER:- minicomputer also called mid-range servers, are more powerful computers than micro computer in terms of processing power and capabilities. Minicomputers are mainly multiuser systems where many users  simultaneously work on the systems. Mi-n+icomputers posses greater storage capacity and larger memory as compared to microcomputers. These are even capable of handling more input-output devices.
 Examples are PDP-11, VAX, 7500 MAGNUM etc.

       (iv)        MAINFRAME COMPUTER :- These are designed to handle huge volumes of data and information. These can support more than hundred users at same time. These are very algre and expensive computers have great processing speeds and very large storage capacity and memory as compared to minicomputers. These computers even possess and work with more than one processor at the same time. Thus one can say these are multiuser, multiprocessor systems. For mainframe computers very sophisticated operating systems are needed to control and supervise their operation.

Example are :- ICL 39, CDC 6600, VAX 8842, IBM 3090/600, IBM4381.

(v)         SUPERCOMPUTER :- Super computer are the most powerful computers among digital computers. These consist of several processors running together thereby making them immensely faster and powerful. These computers are capable of handling huge amount of calculations that are beyond human capabilities. Super computer can perform billions of instructions per second. Some of the today’s super computers have the computing capabilities equal to 40,000 micro computers. These are mainly used in applications like weather forecasting,nuclear science research,seismology, metrology etc.

Examples are :- CRAY X-MP-14, CDC-205, ETA GF-10, FUJITSU VP-400, NEC SX-2 etc

2        ANALOG COMPUTERS:-  In analog computers, continuous quantities are used. Computations are carried out with physical quantities such as voltage, length, current, temperature ate. The devices that measure such quantities are analog devices. E.g. voltmeter, ammeter. Analog computers operate by measuring rather than counting. The main advantage of analog computers is that all calculations take place in parallel and hence these are faster but their accuracy is poor as compared to digital computers. Analog computers are mostly used in engineering and scientific applications. An electronic weighing scale is an example of analog computers.

3.     HYBRID COMPUTERS :- Hybrid computers utilize the best qualities of both the digital and analog computers. In these computers some calculations take place in analog manner and rest of them take place in digital manner. Hybrid  computers are best used in hospital where analog part is responsible for measurement of patient’s heart beat, blood pressure, temperature and other vital signs and then the operation is carried out in digital fashion to monitor patient’s vital signs. Hybrid computers are also used in weather forecasting.

Analog and hybrid computers perform specialized tasks but the digital computers are used almost everywhere in business and scientific applications.