Fourth Generation of Computers: Features & Examples

The fourth generation of computers is commonly associated with the introduction of microprocessors in 1971 and the expansion of personal computing through the 1970s and 1980s. Placing CPU functions onto integrated chips helped reduce the size and cost of many computers, while advances in semiconductor memory, software and manufacturing enabled increasingly capable systems.

In the familiar five generation classification of computers , the transition from the third to fourth generation is often explained as a move from computers assembled using numerous integrated circuits toward systems built around microprocessors. This is a useful teaching framework, not a universally agreed historical boundary: technology adoption varied by manufacturer and type of machine.

What Is the Fourth Generation of Computers?

Fourth generation computers are generally described as computer systems developed during the microprocessor era, beginning around 1971. Unlike earlier processors constructed from multiple boards or assemblies, a microprocessor implements the central processing unit's main functions in a single integrated circuit. Not every computer made after 1971 used a single chip CPU, and a fourth generation ending date is not consistently defined.

Intel introduced the 4004 commercially in 1971. It was a 4-bit microprocessor containing approximately 2,300 transistors not millions or billions. Later generations of chips used greater levels of integration, including very large scale integration (VLSI), and eventually incorporated vastly more transistors.

Key Characteristics of Fourth Generation Computers

1. Microprocessor Based Design

A microprocessor brings instruction decoding, arithmetic and control functions together in a chip. This simplifies computer design compared with assembling CPU circuitry from many discrete packages. The processor still needs memory, power, clocking and interfaces to become a functional computer. To understand the broader components, see the block diagram of a computer .

2. Increasing Integration and Semiconductor Memory

Large scale and very large scale integration made increasingly complex chips economical to manufacture. RAM and ROM based on semiconductor technology became widely adopted alongside microprocessors. Learn the distinction between storage and primary memory before comparing early computer systems.

3. Growth of Personal and Microcomputers

Microprocessor kits and systems made computing accessible to hobbyists, small businesses and eventually households. The Altair 8800, Apple II and IBM PC reflect different stages in that expansion; they did not appear at the same time or provide identical capabilities.

4. Improved Software and Interfaces

Systems increasingly supported BASIC, C and other programming languages, followed by graphical interfaces on selected personal computers. These capabilities evolved over time; not all early microcomputers had keyboards, graphical displays or multitasking operating systems.

5. Networks and Persistent Storage

Floppy disks, hard disks and networking became important across successive product generations. They are developments of the wider era rather than features unique to the original 1971 microprocessor.

How Does a Fourth Generation Computer Work?

A typical microprocessor-based computer fetches instructions from memory, decodes them and performs the specified operations. The control logic coordinates execution, the arithmetic logic unit carries out numerical and logical operations, and registers hold frequently used values. Peripherals connect through input/output interfaces.

At a high level the flow is input → processor and memory → output . A user may supply input with a keyboard or another input device ; processed results are sent to an output device or stored for later use. The exact organization depends on the system architecture.

What Is a Microprocessor?

A microprocessor is a programmable integrated circuit implementing CPU operations. Its instruction set defines operations the processor can perform, including arithmetic, logical comparisons, data movement and branching. A microprocessor is not the same as a whole computer: it normally requires additional memory and peripheral hardware, although modern processors may include caches and integrated controllers.

Early microprocessors were limited by small word widths, modest clock speeds and memory constraints. The Intel 4004, Intel 8080 and later Intel 8086 illustrate different steps in this evolution. Modern systems have far higher integration and very different performance characteristics.

A related device is the microcontroller, which usually integrates a processor, memory and peripherals intended for embedded control. Our upcoming microprocessor vs microcontroller comparison explains the differences in more detail. Editorial note: activate this link only after the new article is published.

Examples of Fourth Generation Computers

Micral N (1973)

The Micral N was an early commercial microprocessor based computer using the Intel 8008. It demonstrates the transition to a CPU on a chip but did not look or operate like a modern laptop.

Altair 8800 (1975)

The MITS Altair 8800 used the Intel 8080 and became influential among personal computing enthusiasts. Its early configurations used front panel switches and indicator lights rather than a built in screen and keyboard.

Apple II (1977)

Apple II helped bring ready to use microcomputing to homes, education and small businesses. It used a MOS Technology 6502 microprocessor and supported an expanding software ecosystem.

IBM PC (1981)

The IBM Personal Computer model 5150 used an Intel 8088 processor. Its widespread adoption helped establish conventions for the PC ecosystem.

Third vs Fourth Generation of Computers

Read third generation computers for historical background, including why not every 1960s mainframe used the same integrated circuit technology.

Advantages of Fourth Generation Computers

• Smaller CPU circuitry enabled compact systems and lower assembly complexity.
• Mass production made many forms of computing progressively more affordable.
• Semiconductor advances improved processing capability and memory options.
• Personal computing broadened access to programming, productivity software and education.
• More standardized platforms encouraged peripherals and software ecosystems.

Limitations of Fourth Generation Computers

• Early microcomputers often had limited RAM, storage and graphics capabilities.
• Software compatibility differed substantially between systems.
• Design and fabrication required significant investment and expertise.
• Processors still generated heat; cooling requirements depended on power consumption and enclosure design.
• Some early systems needed technical skills to assemble, program or operate.

Conclusion

Fourth generation computers are best understood through the rise of the microprocessor and its impact on the spread of personal computing. The era brought major progress in integration, memory, software and affordability, but these changes happened over decades rather than at a single point in history. For the broader sequence, read the generations of computers and the preceding third generation computers .

Further Reading

• Generations of Computers
• Block Diagram of Computer
• Primary Memory
• Input Devices
• Output Devices
• TCP/IP Model