History of Computers

First Generation

Time Duration: 1940 – 1956 Technology Used: Vacuum Tubes

These computers relied on binary-coded language (i.e., 0s and 1s) to perform operations and were capable of solving only one problem at a time.

Examples: ENIAC, EDVAC, UNIVAC

Characteristics of First Generation Computers:

1. Non-portable and very slow equipment.
2. Very large in size, requiring a lot of space for installation.
3. Unreliable as they were prone to frequent hardware failures.
4. Programming was difficult since only machine language was used.
5. Computational speed was measured in milliseconds.

Second Generation

Time Duration: 1956 – 1963 Technology Used: Transistors

Transistors replaced vacuum tubes in this generation. A transistor is made of semiconductor materials like Germanium and Silicon. One of the major developments during this time was the shift from machine language to assembly language.

Examples: PDP-8, IBM 1401, IBM 7090

Characteristics of Second Generation Computers:

1. Smaller compared to first generation computers.
2. Computational time reduced from milliseconds to microseconds.
3. More reliable and less prone to hardware failure; required less maintenance.
4. Programming became faster and less cumbersome.
5. More portable and generated less heat.

Third Generation

Time Duration: 1964 – Early 1970s Technology Used: Integrated Circuits (ICs)

An Integrated Circuit (IC) combines many components such as transistors and resistors on a single chip. These computers introduced keyboards, monitors, and operating systems, allowing multiple applications to run simultaneously.

Characteristics of Third Generation Computers:

1. Computational time reduced from microseconds to nanoseconds.
2. More portable and reliable than second generation computers.
3. Smaller in size compared to previous generations.
4. Commercial production became easier and cheaper.
5. Manual assembly of individual components was no longer required, but manufacturing ICs required sophisticated technology.

Fourth Generation

Time Duration: Early 1970s – 2000s Technology Used: Microprocessor

This generation extended third-generation technology. In 1971, engineers developed a microprocessor — a tiny chip integrating the CPU, memory, and input/output controls on a single circuit. It marked the era of Large Scale Integration (LSI), Very Large Scale Integration (VLSI), and Ultra Large Scale Integration (ULSI).

Examples: Apple II, ALTAIR 8800, CRAY-I

Characteristics of Fourth Generation Computers:

1. Very small in size.
2. Low production cost, making computers more affordable.
3. Portable and highly reliable.
4. Introduced Graphical User Interfaces (GUI) and pointing devices for ease of use.
5. Networking and interconnection improved communication and resource sharing.

Fifth Generation

Time Duration: 2000 – Present Technology Used: Touch Sensors, Artificial Intelligence (AI)

The fifth generation is still evolving, driven by Super Large Scale Integration (SLSI) technology. These computers are designed to respond to natural language inputs, recognize touch and vision, and exhibit elements of artificial intelligence — learning, reasoning, and decision-making capabilities.