Computer Notes Chapter- 5 CLASSIFICATION OF COMPUTER ! Classification according to Date - Handling capabilities ! Analog Computer ! Digital Computer ! Hybrid Computer ! Classification according to Functionality ! Micro Computer ! Mini Computer ! Mainframe Computer ! Super Computer !l

CLASSIFICATION OF COMPUTER 

Today, computers come in multiple shapes, size and types, ranging from those that fit in the palm of your hard or hide in the corner of your microwave or VCR  to those that occupy entire rooms: from the ones generally used by one peroson at a time to those  simultaneouly used by dozens or even hundreds of people. Computer also differ in their data processing ability, e,g. some computer work on digital data, while some might work on analog data. Computers are classified on the basis of following: 

1. Data Handling :  Whether the computer is using analog, digital data, or a combination of both. 

2. Functionality:   Whether the volume of work that the computer can handle is large or small. 

        

    Computers are meant for different purposes. They can be used either for general or for a specific purpose. General- purpose computers are designed to handle a variety of problem and are used in countless applications. A general - purpose computer can be used for varied applications such as payroll, inventory control, budgeting. Amd sa: es amalsis. Although, such machines are versatile but they normally lack speed efficiency. A specific purpose computer designed to handle a specific problem or to perform a specific task. Examples os special purpose computers are those used for collection highway tolls, airline reservations, satelite  tracking, air traffic control, and industrial process control. These systems may lack versatility but they perform their specific task very efficienty and quickly. 

Classification according to Data - Handling capabilities :

 Various types of computers process the data in a different manner, and according to this basic working principle, they classified into the following three categories. 

1. Analog Computer

2. Digital Computer

3. Hybrid Computer

Analog Computer 

  The term analog means continuous wave or data such as electronic current and any device. which measures this continuous data by some system of unit such as speed, pressure, etc, can be termed as analog computer. The data, which does not, changes in steps, but changes in a smooth continuous manner can be measured by some  physical quantities and can be termed as continuous data, e.g. Analog devices are speedometer of an automobile, voltmeter, etc. The basic operation of these devices is first measuring the data and then counting it. In computers, the variable that is to be measured is an electrical current. Analog computers are specific purpose devices. They are very fast in operation because all the measurements are achieved in truly parallel mode, i.e. they can perform several calculations at the same time.

Digital Computer :

 Digital means data consisting of discrete levels. Devices that work (manipulate) with these discrete stages, e.g. performing arithmetic and logic operations on them, are known as digital computer. In computers, these discrete levels are represented by binary digits (0s and 1s ) where 0 means absence of electric current and 1 represent presence of electric current. Now days, we preliminary use these kind of computers. Digital computers perform counting rather than measuring the data, which is done in analog systems. A digital computer performs sequential operations one at a time and operates on discrete (non continuous) numbers. They are more accurate, precise, and faster than analog computers. 

Hybrid Computer : 

  Hybrid computer are  machines that incorporate both analog as well as digital feature in a single computers and the counting feature of computer. These computers are acquired by connecting a digital and an analog computer via a hybrid interface. The digital unit controls the analog unit with the help of stored instructions and the analog unit interpolates digital unit for various I/O operations. These computer are used to solve special type of problems relating to science and engineering, such as space vehicle simulations, training of  astronauts, etc.

Classification According to Functionality :

   Computer differs in performance, size and cost. Depending upon these parameters, the computer industry classifies them into the following categories. 

1. Micro Computer 

2. Mini Computer 

3. Mainframe Computer

4. Super Computer 

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

Micro Computer:

 i. This is the smallest category of computers.

ii. It consists a microprocessor and associated storage device and input and output devices. 

iii. Due to very large scale integrated technology, now a microcomputer is available in very small size.  Example- Personal Computers (PC).

   

     PCs are of following types-

              

       a. Desktop- place on the top of the desk.

       b. Portable Computer

                      

            i. Laptop -Set on the lap of the user.

            ii. Personal Digital Assistant (PDA).

            iii. Hand- held or Mobile Computer.

a. Desktop computers are lower and computers meant for common users. They are termed as desktop computers because these computers are placed on the top of the user's . Desktop computers or PCs (Personal computers) are used to store data and program required by the user. 

b. Portable computers are similar to desktop computers but unlike desktop computers they are mobile, i.e. the user can carry these computers with them wherever they go. Portable computers can be of many types namely, laptops, palmtops, etc.

I.      Laptop Computer:  Laptops are small PCs with all the features of latest computers in a compact form. They are small, light in weight and portable. Laptops are more expensive than desktop computers. They are also referred as notebook. Laptop does not require any external power source as they have an inbuilt battery, which can be changed from any electrical socket. 

II         Personal Digital Assistant (PDA):  Also known as palmtop, These are the smallest of portable computers, which user a pen or an electronic stylus, father than a keyboard for input. PDAs are less powerful than PCs or laptop and are used special purpose like creating spreadsheets , maintaining address book or storing telephone numbers. They do not have disk drivers rather they use small cards to store the programs or data.

III.      Hand-help or Mobile Computer:  These are microprocessors, which can store the information in devices like mobile sets, digital diary, etc. These chips possess a very small memory and therefore can store little information like phone number, call records, short message etc. 

  

Mini Computer :

 i. Term Minicomputers originated in 1960

 ii. 16-Bit minicomputer was more powerful machine, could be used in variety of applications and                could support business application along with the scientific applications.

iii. Mini computer used as multi-user system.

iv. 32-Bit microcomputers  known  as super minicomputers.

v. Cost of minis is lower than the Mainframe.

vi. It supports 10 to 12 terminals. 

Mainframe Computer :

  i. They are 32-bit machine or on the higher -side.

  ii. It Can handle all kinds of scientific and business applications.

  iii. More thand 1,000 terminals can be supported by mainframe. 

 iv. Example- ES/9000 family of computers of the IBM(International Business Machines) corporation.

Super Computer:

 Super computers are at the apex of the computer range.They are the faster and the most expensive machines and are considered a national resource. An existing super computer may have several processing units working together to produce a billion or more scientific operation every second. Initially , used for weapon designing, currently they are being used for commercial purposes like designing automobiles that will offer better protecton to passengers in case of accidents. Some to other areas in which super computers are being used are weather forecasting, biomedical research and aircraft design. Recently CDAC  India has also built its own super computer named PARAM,  which is primarily used for weather forecasting Other examples of super computers are CRAY-3, Cyber205, etc.