Operating systems have changed over time. As a result, their evolution over time may be traced using operating system generations. Operating systems are classified into four generations. These can be summarized as follows:

Vacuum Tubes and Plugboards: The First Generation (1945-1955)

Digital computers were not invented until after World War II. At the time, calculation engines with mechanical relays were constructed. Mechanical relays, on the other hand, were extremely slow and were eventually replaced by vacuum tubes. These machines were massive, yet they were still quite slow.

A single group of people planned, manufactured, and maintained these early computers. Because there were no programming languages and no operating systems, all programming was done in machine language. All of the questions were straightforward numerical calculations.

Punch cards were used in the 1950s, which improved the computer system. Programs were written on cards and read into the system rather than using plugboards.

Transistors and Batch Systems in the Second Generation (1955-1965)

Transistors paved the way for the creation of computer systems that could be mass-produced and supplied to paying consumers. These machines were known as mainframes, and they were kept in air-conditioned computer rooms with personnel to operate them.

The Batch System was created in order to eliminate computer waste. In the input room, a tray of jobs was collected and read onto magnetic tape. The tape was then rewound and placed on a tape drive. The batch operating system was then loaded, which read and ran the first job from the tape. The output was recorded on the second tape. The input and output tapes were removed after the batch was completed, and the output tape was printed.

Integrated Circuits and Multiprogramming in the Third Generation (1965-1980)

Until the 1960s, there were two kinds of computer systems: scientific computers and commercial computers. IBM merged these in the System/360. This utilized integrated circuits and offered a significant cost and performance advantage over second generation systems.

Multiprogramming was also implemented in third-generation operating systems. This meant that the processor was not idle when a job was performing I/O. Another job was scheduled on the CPU to avoid wasting its time.

Personal Computers, Fourth Generation (1980-Present)

With the introduction of large-scale integrated circuits, it was simple to manufacture personal computers. These were chips with thousands of transistors packed into a square centimeter of silicon. Because of these factors, microcomputers were substantially cheaper than minicomputers, allowing a single person to acquire one.

The introduction of personal computers resulted in the expansion of networks. This resulted in network and distributed operating systems. While utilizing a network operating system, users were aware of a network and could log in to remote workstations and copy files from one machine to another.