Ace Computers (Pilot and Jupiter)

In the interests of the online documentation of obscure connections.

Several years ago, I attended a celebration of the life of Alan Turing (1912-1954) at King's College Cambridge. Turing is recognized nowadays as an influential pioneer in the history of Computer Science and Computers. His key contributions to British code breaking work at Bletchley Park during World War II have historical significance. At the King's event, it was fascinating to meet several of the people who had worked with Turing; a reminder of how young computer technology really is.

This recollection came to mind recently while reading an article (How Alan Turing's Pilot ACE changed computing) on the BBC website. The Pilot Ace was an early computer designed by Turing and developed at the British National Physical Laboratory (NPL) from 1946 to its release in 1950. For several years, the Pilot Ace was used for commercial applications and can now be seen in the London Science Museum. The BBC article refers to a radio interview with Tom Vickers, operations manager on the Pilot Ace project (As of writing, the interview is still available via Harriet Vickers blog where the interview starts 11 minutes into the podcast).

An early home computer called the Jupiter Ace was released in 1982, an untypical device of its time based around the FORTH programming system, an approach that yielded a little more efficiency than similar machines of that era which were mostly programmed using interpreted BASIC.

Computing technology had advanced considerably since the era of the Pilot Ace 30 years earlier but the two devices in their own way illustrate the challenge of trying to work with hardware not quite ready for prime time yet interesting nevertheless. A basic Jupiter Ace came with 1024 bytes (1K) of main memory, expandable to 49x1024 bytes (49K). The Pilot Ace originally had 512 bytes main memory, later expanded to 1408 bytes (implemented using vacuum tubes!) with a 16K byte drum memory peripheral.

Now for the obscure part. The Jupiter Ace ROM software was written by Steve Vickers. Steve had already written much of the ROM software for the Sinclair ZX home computers, popular hobbyist type machines in the UK of the early 1980s. The name "Jupiter Ace" was inspired by the work of his father Tom Vickers on the Pilot Ace. Generations.

It is now 60 years since the Pilot Ace release. Almost 30 since the Jupiter Ace and the computing landscape has changed far more dramatically in the last three decades than in the first three following Turing's work. A myriad of observations could be made but I'll simply note that commonplace telephones nowadays have a billion times more memory than the Pilot, and hundreds of thousands more than the Jupiter.

Perhaps it is time for another Ace computer.