TYPES OF COMPUTERDue to different behavior of computer we can divide it in three types according to it
- Analog computers show the continuity of specified value means, which are used to measure continuous values.
- Analog computers operate by measuring rather than counting.
- An examples are analog clock, thermometer.
- Digital computers based on the rule of counting. These directly count numbers.
- In fact digital computers used signals, which can distinguish between just two values 0 and 1.
- Digital watches are the example of digital computers.
- Desktop computers and Laptop are also the examples of digital computers.
- The combination of Analog and Digital computer is called Hybrid.
- These are better and widely in used.
- A part of processing is done on analog and a part of processing is done on digital computer.
- An example of Hybrid computer system is a cement plant where all calculations are made by digital computers and action such as increase/ decrease in certain material by analog computer.
GENERATIONS OF COMPUTERS
First Generation Computers (1942-1955)
Second Generation Computers (1955-1964)
Third Generation Computers (1964-1975)
Fourth Generation Computers (since 1971)
Fifth Generation Computers (Present- Beyond)
FIRST GENERATION COMPUTER (1942-1955):
- The vacuum tube technology was used in first generation computers.
- MARK-1, ENIAC, EDVAC, UNIVAC-1 etc machines belong to the first generation of computers.
- Vacuum tubes were only electronic components available during those days.
- Vacuum tube technology made possible the advent of that time.
- They could perform computations in milliseconds.
- Too bulky (large) in size.
- Air-conditioning required.
- Thousand of vacuum tubes were used to produce large amount of heat and burnt out frequent.
- Not portable.
SECOND GENERATION COMPUTERS (1955-1964):
- The transistor technology was used in second generation.
- It was invented in 1948 at Bell laboratories.
- The transistor is smaller in size and more reliable than vacuum tube.
- Smaller in size as compared to first generation computers.
- More reliable.
- Less heat generated.
- These computers were able to reduce computational times from milliseconds (10-3) to microseconds (10-6).
- Better portability.
- Air conditioning required.
- Commercial production was difficult and costly.
- Frequent maintenance required
THIRD GENERATION COMPUTERS (1964-1975):
- The IC (integrated Circuits) technology was used in third-generation.
- It is small in size (upto 5mm square).
- A circuit having large number of electronic components like transistors, capacitors etc.
- Maintenance cost was low because failure rate of hardware was very low.
- Portable and more reliable.
- Easily movable.
- Less power requirement than previous generation computers.
- Commercial production was easier and cheaper.
- Air conditioning required in many cases.
- Highly difficult technology required for the manufacture of IC chips.
FOURTH GENERATION COMPUTERS (SINCE 1971):
- The microchip technology was introduced in this generation. With the advancement in IC technology, LSI (large Scale Integration) chips were developed.
- After LSI, the VLSI (very large scale Integration) was developed and made the development possible.
- Using VLSI technology the entire CPU is designed on a single silicon chip.
- Smallest in size because of high components density.
- Very reliable.
- Heat generation is low.
- Large memory.
- Portable and reliable.
- Cheapest among all generations.
- Highly difficult technology is required for the manufacturing of microprocessor chip.
- Fifth Generation Computers (Present- Beyond)
- Having their own thinking power.
- Making decisions themselves.
- Having capabilities of learning.
- ULSIC (Ultra Large Scale Integrated Circuits) technology.
- Artificial Intelligence