Notable early computers
Notable early computers are computers which marked significant steps on the road from early computing devices to the widespread adoption of computers. The ones given below are the ones which the author of this page deems the most significant ones.
Depending exactly how one defines 'computer', some of those early stored program computing devices might have been computers. If a computer has to be able to modify its own program, none of those qualify. If it only has to have the ability to do conditional branches, those were added to the Automatic Sequence Controlled Calculator and Zuse Z4 later in their lives.
The earliest computers
Babbage's Analytical Engine would unquestionably have the pride of place here, but sadly, he never produced a working instance. It was definitely a true 'stored program computing device' although it could not modify its own program, and lacked some common capabilities seen in many later machines (such as hardware support for subroutines and stacks) - but the need for them was not obvious to designers of the early machines, either, until they started to do actual work on them.
Whether the ENIAC was merely the last step before true computers ('merely' a large digital electronic computing device), or (eventually) a true computer, is a fairly complex question. As originally designed, it was only configurable, requiring considerable effort to re-configure it to perform a different computation (although it was general-purpose, unlike the Atanasoff-Berry Computer and Colossus). In 1947 an effort was started to re-configure it in a way that added a certain amount of programmability, via a program stored in the 'function-table switches' (originally intended as a EPROM data source). Later, minor hardware modifications improved ENIACs efficiency when configured as a stored-program machine; it started to operate in that mode in 1948. However, it apparently never had the capability to modify its program, which is, to some people, the hallmark of a true computer.
Whether it, or the Manchester Baby, was the first true computer, is thus an open question. The latter was more of an 'experiment' (used for testing the then-new idea of Williams tube main memory) than a 'prototype' - although it very quickly had more capable descendants.
British machines
The first operational and generally-available computer anywhere was the Cambridge EDSAC. A copy of it was the LEO, the first computer to do business work anywhere.
Among the first computers in the UK was the Manchester Mark I (it being a re-built and considerably expanded Baby); copies were made available as the Ferranti Mark 1, the first commercially-available computer.
The UK had a third computer effort, one that was (unusually) not connected to the flurry of work set off by the Moore School Lectures; its design in late 1945 preceded those. That line started with the ACE, designed by Turing himself; when slowness at the NPL, its home institution, delayed it, a scaled-down version, the Pilot ACE was done instead. This too was commercially copied, as the DEUCE.
American machines
The design of the EDVAC started very early, in August, 1944. As an actual machine, it was not that influential, because after it was designed, the team that had done so scattered, which led to a considerable delay before it was actually built, completed, and working. Its real importance is because of its very early architectural design document, the widely-distributed First Draft of a Report on the EDVAC, which set the path for essentially all later computers.
Whirlwind, at MIT (which set MIT off doing important work on computers for many decades), was important for several reasons, not just its early start. (Work on it started, in a way - the project which produced it originally started as an effort to produce a general-purpose flight simulator - in 1944.) It was the first real-time computer, unlike all the other first-generation computers, which were intended only for large-scale numerical computations. It was also used interactively, rather than in batch processing mode - which set the path for almost all of today's computers. Whirlwind was also the first computer with core memory, which was the main memory technology which made widescale use of computers practical.
The IAS computer and its many copies, built by a team led by von Neumann, served to spread detailed engineering knowledge of the then-state of the art of digital electronic computers very widely, across the world. The IBM 701, which set IBM on the path which led to it standing across the world of computers like a Colossus for several decades, was apparently a 'cleaned up' copy.
It was, however, the UNIVAC I of Mauchly and Eckert which was the first commercially-available computer in the USA - marking the birth of an industry/field that the US slowly came to dominate.
See also
Further reading
- Paul E. Ceruzzi, Reckoners: The Prehistory of The Digital Computer, From Relays to the Stored Program Concept, 1935-1945, Greenwood, Westport, 1983
- William Aspray (editor), Computing Before Computers, Iowa State University Press, Ames, 1990
- Brian Randell (editor), The Origins of Digital Computers: Selected Papers, Springer-Verlag, Berlin, Heidelberg, New York, 1973, 1982 (3rd edition)
- Nicholas Metropolis, Jack Howlett, Gian-Carlo Rota (editors), A History of Computing in the Twentieth Century, Academic Press, New York, 1980
- Raúl Rojas, Ulf Hashagen (editors), The First Computers: History and Architectures, MIT Press, Cambridge, 2002
- Simon H. Lavington, Early British Computers, Manchester University, Manchester, 1980
