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Jupiter Ace

Updated on March 9, 2017
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Martin has been a software developer for many years. This is mixed with a passion for retro machines and game,

Jupiter Ace

The Jupiter Ace was a British home computer that was available in the early 1980s.

The machine was produced by a company with the rather awesome name of Jupiter Cantab.

This is a lesser known machine from the annals of computer history that preceded the boom years of the VIC 20, ZX Spectrum, Commodore 64, Amstrad CPC 464 and BBC Micro.

For some people it would have been their first machine before they upgraded to one of the newer and more powerful computers mentioned above.

So let's take a look at a machine that is not overly known, and as such is more difficult to get hold of nowadays...

What does a Jupiter Ace look like?

You can tell the Jupiter Ace is more than 30 years old...
You can tell the Jupiter Ace is more than 30 years old...

The Jupiter Ace, a good alternative to the ZX81

The Jupiter Ace differed from other computers of the era in that it used FORTH as the built in language, instead of the more traditional BASIC that tended to be a stalwart of 8-Bit machines.

FORTH as a language, combines high performance and code compactness with the programming benefits of high-level programming languages, such as ease of use and learning.

This language was chosen by Jupter Cantab as it was well adapted to microcomputers with a small amount of memory and relatively low-performaning processors.

FORTH allowed control structures to be nested to any level with the only limitation being the machines available memory.

FORTH also allows implementation of machine code assembly routines, which meant that certain tasks within a program could be executed this way; again giving a fantastic performance boost with little overhead.

The choice of FORTH did make the machine stand out from the crowd a little and was obviously a good choice for anyone wanting to learn a language other than BASIC.

The Jupiter Ace Technical Overview

The Jupiter ACE is (and often was) compared to the ZX81 due to its similar size and low cost. Despite this comparison, internally the computer was of a completely different design.

The ZX81 used 75% of its CPU time (the trusty Z80 processor) to drive the video. Not in this machine though; here the Z80 CPU was fully utilised for running programs.

The ACE was blessed with a dedicated video memory of 2 Kilobytes (yes a whopping 2 KB!), leaving the 1 Kilobyte of main memory free for user programming.

If you wanted to learn how to write efficient code then this machine would certainly show you how!

The Jupiter Ace was new to the market and the designers could not afford to use a 'ULA' (uncommitted logic array),which were common in other computers such as the ZX81. The logic array could not be used as they had to keep the component count as low as possible.

By clever design the creators of the machine managed to use less chips overall which was a fantastic method of saving motherboard space.

Just like the Sinclair Spectrum, the Ace was 'blessed' with black rubber keys for the would-be typist. This rubber 'dead flesh' keyboard on both machines was never great, but you did get used to it after a while.

Audio capabilities were CPU controlled with programmable frequency and duration.

Sound output was through a small built-in speaker, again very similar to the likes of the ZX Spectrum. A television was needed as a display device (no monitor was available) which, just like the ZX80 and ZX81 was monochromatic only.

As usual for the era data was saved from the machine and loaded into the machine via a standard cassette tape; a standard portable cassette player could be connected to the machine.

Those 8-Bits Of Jupiter Ace Power

How fast could you type on one of these? The Jupiter Ace
How fast could you type on one of these? The Jupiter Ace

The Jupiter Ace Never Quite Took Off

Various add-ons became available for the machine such as various RAM packs which would boost the overall memory to 16KB, 32KB and a huge 48KB!

With 48K to play with you could put together a pretty lenthy and feature rich program in Forth - so for those that liked to dabble in programming a RAM pack could really open up the possibilities to you.

It was also possible to pick up a better keyboard, a printer and (gasp!) an external disk-drive. A disk-drive back in 1980-81 was a real luxury item - not many of us had them at home.

A sound board was also available for the Ace (manufactured by Essex Micro Electronics) which presumable allowed you to create sounds which were, ace!

Depsite these great peripherals the machine never went on to be a huge seller - in fact it is not very likely that it sold any more than 10,000 units during it's pretty short commercial life-span.

It was never a good choice for school use either as it just was not robust enough for classroom life. Many companies tried to get a foothold in the educational sector but it was Acorn who ended up top trumps in schools and colleges with their excellent (and robust!) BBC Micro.

Very few computer games made it onto the machine (although there are some real gems available for it and versions of those classic arcade games) and unfortunately it ended up being swept aside as the Spectrum and Commodore 64 took hold of the home market in the UK.

Magazine advert for the Jupiter Ace

A magazine advert for the Jupiter Ace micro-computer complete with order form
A magazine advert for the Jupiter Ace micro-computer complete with order form

Moon Buggy Was Unreleased On The Jupiter Ace

Steve Benway takes us on an Ace Voyage to Jupiter

Ace Invaders - Jupiter Ace

A Rare Jupiter Ace Game - Ace Invaders

Here is one of the few games that was created for the machine.

Ace Invaders is (as you would guess) a version of the classic arcade game Space Invaders.

There is nothing else I can really say about it apart from that plays as you would expect. Shoot the invaders, avoid their bombs and clear the screen!

By any stretch it is always good too see versions of classic games on such a rare and vintage machine!

Snake - So Simple Yet Always Fun On The Jupiter Ace

Micro Maze On The Jupiter Ace

Classic Jupiter Ace Platform Action In Jumpman

Classic Shmup Action In Meteor Racer On The Jupiter Ace

Demo Scene On The Jupiter Ace?

Clever coders still work on machines such as this.

New demo's and games are still being created for the Jupiter Ace - have a look at the impressive demo below.

This just shows how far this older technology and hardware can be pushed. I doff my cap!

Let The Jupiter Ace Demonstration Commence!

The Jupiter Ace For The Collector

As we know sales of the machine were never very large (less than 10,000 units were sold originally) and as of the early 2000's Jupiter Ace's are relatively uncommon.

This of course leads to high prices as collector's items and good condition units are not easy to find.

One main reason for low sales back in the early 1980's seems to have been the need to buy the extra 16 Kilobyte RAM pack extension, which almost doubled the price of the machine.

The absence of any colour capability on this machine also kept the ACE squarely in a niche market of programming enthusiasts. As soon as the other colour 8-bit machines started to appear the ACE's days were well and truly numbered.

Prices for these machines on Ebay are usually quite high, and good quality examples will certainly fetch a good price.

Dark Star On The Jupiter Ace

Any Fans Of This Computer?

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    • Crewman6 profile image


      8 years ago

      Another informative hub. I love seeing these 'captures' of computing history. This one sounds like it came out about the time Shatner was touting Vic-20 as the 'Wonder Computer of the 80's"


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