1. Computer Generations

2. Key for Computer Generations
Year
Components used
Memory
Operating Speed
Example
Language Used
1st
Vaccum tubes/thermonic valves
Magnetic drum (10, ,000 characters)
Milli sec
ENIAC
EDVAC
EDSAC
Machine language
2nd
Transistor
Magnetic core and disk. (Up to 64,000 characters)
Micro sec
PDP-8 IBM1401 IBM7090
Assembly lang,
Mnemonics
3rd
1964-early 1970’s
Integrated circuits
Semi-Conductor
(Up to 4 million characters)
Nano sec
NCR 395 B6500
High level lang,
BASIC,FORTAN,PASCAL
4th
Early 1970-till date
Micro processor
1-10 nano sec
Apple II,
Altair8800CRAY-1
4GL
5th
Present & beyond
Artificial Intelligence
CMOS
1-100 nano sec -

3. First Generations
These computers used vacuum tubes for circuitry and magnetic drums for memory.
It is a metal cylinder coated with magnetic iron-oxide material on which data and programs can be stored.
Input: punched cards and paper tape.
Output was displayed on printouts.
It is a binary coded language to perform operations and was able to solve only one problem at a time.

5. Advantages: Disadvantages:
Vaccum tubes were the only electronic components available at that time.
These computers were the fastest calculating device.
Perform computations in milli seconds.
Very big in size.
No reliability
Non portable.
High heat production.
High power consumption.
High cost.

6. Second Generation
These computers used transistors, which were superior to vacuum tubes. It is a made up of semiconductor material like germanium and silicon.
It usually had three leads and performed electrical functions as voltage, current or power amplification with low power requirements.
It is a simple device; the physical size of computers was greatly reduced.
Magnetic cores were used as primary memory and magnetic disks as secondary storage devices.
Input: punched cards; Output: printout
The major development includes the progress from machine language to assembly language.
Assembly language used mnemonics for instructions rather than numbers Ex: ADD, MULT
High level languages COBOL, FORTRAN also came into existence.

8. Advantages: Disadvantages:
Small in size.
Better Reliability.
Better Portability.
Less heat generated.
Better speed.
Computational time in micro seconds.
High cost.
Frequent Maintenance required.
Manual assembly of individual components.

9. Third Generation 1964- Early 1970’s
These computers used an IC (integrated circuit), which consists of a single chip (usually silicon) with many components such as transistors and resistors fabricated on it.
This development made computers smaller in size, reliable and efficient.
Semi-conductor memory elements replaced the magnetic core memory and magnetic disk fully replaced the magnetic tapes as storage medium.
Users interacted with third generation computers through keyboards and monitors and interfaced with operating system.
Another concept developed during this period was the OS and high level languages. It allows the device to run many different applications at one time with a central program that monitored the memory.

11. Advantages: Disadvantages:
Small in size.
Better Reliability.
Better Portability.
Less heat generated.
Less power consumption.
Computational time in micro seconds.
Need Air conditioning.
Highly sophisticated technology required for the manufacture of IC chips.

12. Fourth Generation 1970’s to till date
The development of microprocessor (circuit containing millions of transistors) integrated with storage, input and output unit produces a micro computer.
A microprocessor is built onto a single piece of silicon known as chip which is about 0.5cm along one side and no more than 0.05cm thick.
It leads to an era of LSI (large scale integration technology) VLSI (very large scale integration )
It became more powerful, compact, reliable and affordable.
It uses Semiconductor memories, which resulted in faster random access main memories and secondary memories such as hard disks.
It also saw the development of the GUIs (Graphical User Interface), mouse and handheld devices.

14. Advantages: Disadvantages:
Much more small in size.
Very cheap compared with previous generation computers.
More reliability.
Less power consumption.
Large & Faster primary & secondary storage.
Highly sophisticated Technology required for the manufacture of LSI chips.

15. Fifth Generation - Present
Computers may operate at incredibly fast speed and perform with unbelievable accuracy. But they are unable to act or think on their own.
When an Artificial Intelligent machine could be developed which will even be in a position to think & decide.
Recent researchers are aimed at designing the logic for the thinking computers for building expert systems and knowledge based systems.

17. Advantages: The super computers fall under this generation.
Portable PC’S also fall under this generation.
Consumes less power.
User friendly
Supports wide OS environments.
Supports newer and powerful applications.
Having faster and large primary storage capacity.

18. Information is Power