Computer Generations

The Evolution of Computing Technology

What is meant by Computer Generations?
Definition
The term "computer generation" is used to describe the major changes in technology that computers went through over different periods.

Each generation is marked by a new innovation in hardware technology (like vacuum tubes, transistors, ICs, microprocessors) which made computers smaller, faster, cheaper, and more reliable.

There are five generations of computers (till now).
The Five Generations of Computers
1
First Generation
1940 – 1956
Technology
Vacuum tubes
Size
Very large (room-sized), consumed huge electricity
Speed
Very slow (milliseconds per operation)
Programming Language
Machine language (0s and 1s)
Input/Output
Punch cards, paper tape, printouts
Storage
Magnetic drums
Examples
ENIAC
UNIVAC
ENIAC had 18,000 vacuum tubes, occupied a big hall, and generated so much heat that cooling was a problem.
2
Second Generation
1956 – 1963
Technology
Transistors replaced vacuum tubes
Size
Smaller, more reliable, less heat
Speed
Microseconds per operation
Programming Language
Assembly language + early high-level languages (COBOL, FORTRAN)
Input/Output
Punched cards, printouts, magnetic tape
Examples
IBM 7094
UNIVAC 1108
A second-generation computer could fit in a room, unlike ENIAC which needed a whole building.
3
Third Generation
1964 – 1971
Technology
Integrated Circuits (ICs = many transistors on a single chip)
Size
Much smaller, more reliable
Speed
Nanoseconds per operation
Programming Language
High-level languages became common (BASIC, PASCAL)
Input/Output
Keyboards, monitors started replacing punch cards
Storage
Magnetic disks (faster than tapes)
Examples
IBM 360 Series
Honeywell 6000 Series
Students could now interact with the computer using a keyboard and monitor instead of punch cards.
4
Fourth Generation
1971 – 1980s
Technology
Microprocessor (entire CPU on a single chip)
Size
Very small, could fit on a desk (personal computers were born)
Speed
Picoseconds per operation
Programming Language
High-level languages like C, C++
Storage
Hard disks became common
Networking
Started connecting computers (early LANs)
Examples
IBM PC (1981)
Apple Macintosh (1984)
Intel 4004 (1971) was the first microprocessor, marking the start of PCs.
5
Fifth Generation
1980s – Present & Beyond
Technology
VLSI/ULSI (Very/Large Scale Integration), AI, parallel processing
Size
Extremely small (laptops, mobiles, embedded devices)
Speed
Millions of instructions per second (MIPS), gigahertz processors
Programming Language
Advanced languages (Java, Python, AI-focused languages like Prolog, Lisp)
Features
Artificial Intelligence, Robotics, Machine Learning, NLP, Quantum Computing (emerging)
Examples
Smartphones (iPhone, Android)
Supercomputers (Fugaku, Summit)
AI-based systems like ChatGPT
Today's smartphones are more powerful than supercomputers of the 1970s.
Comparison Table of Generations
Generation Technology Size Speed Languages Example
1st (1940–56) Vacuum tubes Very large Milliseconds Machine language ENIAC
2nd (1956–63) Transistors Smaller Microseconds Assembly, COBOL IBM 7094
3rd (1964–71) ICs Smaller again Nanoseconds BASIC, PASCAL IBM 360
4th (1971–80s) Microprocessors Desktop size Picoseconds C, C++ IBM PC
5th (1980s–Now) VLSI/AI/Quantum Very small (phones) GHz, AI-based Java, Python iPhone, Supercomputers
Summary
Each generation of computer = new technology breakthrough → smaller, faster, cheaper, smarter.
Room-sized ENIAC (1st gen)
Desktop computers (4th gen)
Smartphones (5th gen)
AI & Quantum Computing