Types of Computer

A. Classification with respect to Purposes

With respect to purposes, computers are divided into two types

1. General Purpose Computers

  • All those computers which are used for general purposes. 
  • A personal computer used for playing games, word processing, Accounting Information System, Management Information System etc
  • These computers can store a huge amount of data.
  • PCs are the example of General Purpose Computers.

2. Special Purpose Computers

  • It is also known as dedicated computers, because these are designed to perform a particular jobs.
  • Perform a single & specific task . 
  • Computer for Games, Computer for controlling traffic lights , ATM etc
  • These systems have predefined set of instructions permanently stored into them, that are designed to perform only one task
  • They are fast in processing.

B. Classification with respect to Function or Logic Used

Computers are classified into three types with respect to Function or Internal hardware structure or Logic used

1. Digital Computers

  • Digital Computers works on discrete data.
  • Discrete data refers to discrete values such as 0, 1.
  • Digital computers works on 0,1(Binary Numbers)
  • These computers based on the presence or absence of an electrical charge or binary 0 & 1.
  • The native language of this class is therefore called binary language (Machine Language)
  • These Systems are more accurate and precise than others
  • Examples: - Personal computer, digital watches etc…

2. Analog Computer

  • Analog Computers works on continues data.
  • Continues data refers to those values that cannot be discrete.
  • Temperature, air pressure, speed, current etc.
  • Analog computer calculates the result by measuring the continuous change in these quantities
  • Analog computers do not require any storage capability because they measure and compare quantities in a single operation
  • These Systems are more speedy than digital
  • Examples: Speed meter, air pressure measurement devices, rain gauge etc.
  • Speedometer of a car measure speed in terms of km/h or m/h, the change in temperature is measured by a thermometer in degrees.

3. Hybrid Computer

  • Combine the best feature of both digital and analog systems
  • Works on both analog and digital data
  • Speedy like analog
  • Accuracy like digital
  • They are used mainly in specialized applications where both analog and digital information needs processing
  • Weather forecasting, Air Defense, Radar Controlling systems, digital petrol pumps etc.
  • In petrol pumps, fuel flow converts into quantity and then quantity is converted into values.


C. Classification Of Computers With Respect To Size

With respect to size, speed, and cost, we can classify computers in the following four types:

1. Micro Computers

  • These computers are small in size.
  • A micro computer use to have Primary memory range from a few Kilobytes to Gigabytes.
  • They are usually designed for personal use therefore they are also called as Personal Computers (i.e. PC).
  • These computers can easily be accommodated on the top of a desk due to their small size and hence are also called as DESKTOP computers.
  • There is another kind of Micro Computer which can easily be placed on the lap and such computer is called as Laptops.
  • Micro Computers are highly flexible. These are also called CHIP Computers because its entire circuitry is fabricated on a single chip.
  • Examples:-IBM, APPLE, COMPAC, RADIO SHACK, COMMODORE, ATARI,
  • IBM compatibles:- 286,386,486,Pentium-I,Pentium-II,Pantium-III,Pentium-IV etc…
  • Handheld PCs (such as PDAs) lack the power of a              desktop or notebook PC, but offer features for users     who need limited functions and small size.
  • A Multi-Core Processor is a processing system composed of two or more independent cores. The cores are typically integrated onto a single integrated circuit die(known as a chip multiprocessor or CMP).

Core

Basic processing area of a computer processor

Die

  • A die in the context of integrated circuits is a small block of semiconducting material, on which a given functional circuit is fabricated.
  • A Dual-Core and Core 2 Duo Processor contains two cores, and a Quad-Core Processor contains four cores.
  • A Multi-core processor implements multiprocessing in a single physical package.
  • Cores in a multi-core device coupled together tightly.
  • Cores may or may not share caches.
  • Dual Core and Core 2 Duo’s are both dual core processor.
  • Core2 duo only takes advantage because
  • The Core 2 Duo has the same L2 cache but it has more cache size than a Dual core. However,
  • There are architectural changes to the silicon that give the Core 2 Duo more sophisticated processing.
  • The single- and dual-core models are single-die, whereas the quad-core models comprise two dies, each containing two cores, packaged in a multi-chip module.

2. MINI COMPUTERS

  • These computers are smaller in size but larger as compared to Micro Computers.
  • Less expensive
  • Primary memory is usually in GIGA Bytes
  • Designed for the computerization of scientific research data.
  • Mini computer usually fills a small shelf because it includes many types of peripheral equipment attached to it.
  • Disks are used for secondary storage
  • Support up to hundred’s of users at a time.
  • Examples: - PRIME-9755,VAX-8650,IBM SYSTEM-36 etc…
  • Application :- Departmental systems, Network Servers

3. MAINFRAME COMPUTERS

  • These computers are very powerful.
  • Large in size, large in memory and powerful.
  • Mainframe computers are also capable of connecting terminals with it.
  • These computers are used in networked environment and mainly as network servers.
  • Mainframe computers are very expansive. They are usually designed for the computerization of huge business organizations, universities, banks, scientific laboratories, national and international markets.
  • Multiple Input/Output devices are normally attached with a Mainframe computer.
  • The secondary storage use to be in the form disks in a Mainframe computer.
  • Mainframes are measured in integer operations per second or MIPS.
  • Example of integer operation is moving data around in memory or I/O devices.
  • These computers also allow different users to work on it at the same time like Mini computers but the number of users can be much more than that of the Mini computers (upto 4000 users can work at a time on a single Mainframe computer).
  • Examples:- IBM-4381, IBM-360, ICL-2900,NEC-610 etc…

4. SUPER COMPUTERS

  • Supercomputer is a computer that is at the frontline of current processing, capacity, particularly speed of calculation.
  • Supercomputers are the most powerful computers.
  • They are used for problems requiring complex calculations.
  • It is not possible to consider one computer system as the most powerful, because the power of a computer is not linear.
  • Super Computers are very difficult to design, it requires lot of research and development and at the same time they are very much expansive to manufacture.
  • Presently approximately 30-50 Super Computers are sold per annum.
  • The speed of a super computer is enormous as it was calculated at a rate of 64 billions instruction per second, like Cray T90.
  • The speed of a supercomputer is measured in "FLOPS"
  • Such as "TFLOPS" (10 power 12 FLOPS)(1,000,000,000,000 ), or "PFLOPS" (10 power15 FLOPS,) (1,000,000,000,000,000 operation per second).
  • Example of floating point operation is the calculation of mathematical equations in real numbers. In terms of computational ability, Supercomputers are more powerful.
  • In February 2009, IBM designed supercomputer with 20 pflops.
  • This will be equivalent to 2 million laptops (whereas Roadrunner is comparable to a mere 100,000 laptops).
  • Application in web services and search engines, online banking (Transaction processing), weather forecasting, Climate Prediction (50 years in 30 days by 4.8 Tflops) , Cryptography, Nuclear weapons (test by simulations), Earthquake and structural modeling and petroleum exploration.
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