TLDR: The Atlas Computer was one of the world's first supercomputers, used from 1962 to 1972. It was known for its virtual memory and was a joint effort between the University of Manchester, Ferranti International, and Plessey Co. Two other Atlas machines were built for British Petroleum and the University of London. A derivative system called Titan was also created for Cambridge University.

The Atlas Computer was a British supercomputer that was in use from 1962 to 1972. It was considered one of the world's first supercomputers and was claimed to be the most powerful computer in the world at the time. When the Atlas Computer went offline, half of the United Kingdom's computer capacity was lost. It was known for being the first machine with virtual memory, which is now a common feature in computers.

The Atlas Computer was a second-generation computer that used discrete germanium transistors. It was developed through a collaboration between the University of Manchester, Ferranti International, and the Plessey Co. Two other Atlas machines were built for British Petroleum and the University of London. Another derivative system called Titan, or Atlas 2, was built for Cambridge University.

The University of Manchester's Atlas Computer was decommissioned in 1971, and the final Atlas machine, the CADCentre machine, was switched off in 1976. Parts of the Chilton Atlas are preserved by National Museums Scotland in Edinburgh. The main console itself was rediscovered in 2014 and is now at the Rutherford Appleton Laboratory in Chilton.

In the background, there was a growing awareness in the UK that they were falling behind the US in computer development. The Atlas Computer was developed as a response to this concern. The design process involved input from various customers and engineering teams. Funding was secured, and the detailed design was completed by the end of 1959.

The Atlas Computer had many innovative features, including a 48-bit word size, virtual memory, and an asynchronous processor. It also had an extracode feature that allowed complex instructions to be implemented in software. The hardware and software were designed to work together seamlessly, with dedicated storage and registers for extracode routines and interrupt routines.

The Atlas Computer was highly regarded in the computer industry and influenced the development of future computers. It was praised for its architecture, large address space, and the introduction of extra codes to extend the functionality of its instruction set. In 2022, an IEEE Milestone was dedicated to the Atlas Computer and the Invention of Virtual Memory.

Overall, the Atlas Computer was a groundbreaking supercomputer that played a significant role in the early development of computer technology. It introduced several innovative features and set the stage for future advancements in computing.