What was the first operating system?

Answer 1

The earliest computers did not use operating systems; a simple loading program was loaded into the computer - via front panel switches or punched tape, the loading program would load the actual program to run. The program would take over the entire machine until it halted or was interrupted by the operator.

This process of loading programs from storage was automated, to some extent, in the 1950s and MIT may be able to claim the earliest such system in 1954 (see attached link).

This is one of the things no one will ever know for sure. When I developed software for the IBM 704 in conjunction with a missile guidance project in 1957, I had never heard of an operating system but I eventually realized that that's what I had created. It's written up in the Annals of the History of Computing, Volume 11 (1989). I can't say that it was first, but it was early, and I don't know any older ones.

In 1961, Burroughs introduced the MCP (Master Control Program) for its B5000 mainframe computer. These early operating systems were little more than loaders. With the advent of high speed disk drives, virtual memory systems and disk control systems became more widely used.

In 1969, Unix was being developed. Unusually for the time, Unix was designed to run on different machines, small device drivers were written for specific hardware, but the bulk of the code was unchanged.

The first microprocessor operating system was CP/M; as with Unix by separating the hardware dependent parts of CP/M from the majority of the code, it made it easy to port CP/M to different hardware platforms (although it was written for the 8080 family of microprocessors).