Operating system


Operating system
Developer	numerous
Publisher	numerous
Platforms	numerous, see operating systems
Released	1947-present
Added to Museum	numerous, see operating systems

An operating system, or OS, is system software that manages hardware and software resources.

Early computers

In the 1940s, electronic digital computers lacked operating systems. Tasks were controlled by switches or by plugs on a plugboard.

Resident monitors

In the early 1950s, general-purpose computers were developed. These computers could run any task given to them, although they could only execute one program at a time.

Another program could not be executed until the task was completed or the computer crashed.

The program was managed by a resident monitor, the precursor of the operating system. The resident monitor was an extremely small program that was resident in the limited memory of the computer.

The resident monitor would control the computer before and after a job by executing non-resident programs for setup and cleanup procedures.

Computers with internal libraries of programs

Another precursor to the operating system came in the mid-1950s. Computers of this era contained libraries of programs.

A program was inserted on external media and one of the internal libraries would be called upon to help with the media inserted.

Examples of the tasks being assisted through the internal libraries include relaying information through input devices or compiling human-readable source code into computer-readable machine code.

The drawback of these internal libraries was that, like the earlier resident monitor, only one program could be executed at a time.

GM-NAA I/O

GM-NAA I/O was the first operating system. It was created in 1956 by Robert L. Patrick of General Motors Research and Owen Mock of North American Aviation for the IBM 704 computer.

It was based on the General Motors-developed resident monitor on the IBM 701.

GM-NAA I/O was designed for batch processing wherein a program would be automatically executed once another program was completed.

SHARE Operating System

The SHARE Operating System was the first operating system that referred to itself as such. It was created in 1958 by the SHARE user group as an improvement on the GM-NAA I/O operating system. As the name suggests, it was designed to improve the sharing of programs.

It was the operating system for the vacuum tube-based computer, the IBM 709, which was released in 1958. It was also ported to the transistor-based update of the 709, the IBM 7090, which was released in 1959.