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Jupiter Ace
Jupiter Ace

Jupiter Cantab’s Jupiter Ace has just turned 30. It is a curious footnote in the history of personal computing.

My review of the Jupiter Ace at Your Computer magazine was published in November 1982. It gets a mention in The Register’s story about the Ace’s 30th birthday.

I still remember the Ace quite well, mainly because it was a quirky home computer. We called them home computers in the early 1980s, the term personal computers came later.

Go Forth with Jupiter Ace

While every other home computer used Basic, the Jupiter Ace used Forth.

Early home computers didn’t have disks or operating system in the modern sense – although you could store programs and data on cassette tape. They mainly had a version of the Basic language stored on Rom.

Basic is an interpreted language. Each line of code is processed or interpreted in turn rather than compiled into machine code. This made it slow.

We need to put slow needs in context here. The Jupiter Ace had an eight-bit processor running at 3.2Mhz. That is roughly 1000th the clock speed of a modern PC.

Forth is still interpreted, but it uses a different structure, so it is many times faster than Basic. It was designed to control radio telescopes, so it was idea for building computer controlled-projects. I had just built a synthesizer and had plans to use the Jupiter Ace to build a drum machine.

However, it was harder to learn and much harder to understand. At the time a friend described it to me as a write-only-language. So the Ace was essentially a computer for serious programmers. That’s not me. I tried to get my head around Forth, but the Ace was soon in a cupboard somewhere collecting dust.

Thanks to Liam Proven @lproven for spotting my name in The Register story.