What is a Jupiter ACE?

The Jupiter ACE was a British home computer of the 1980s, marketed by a company named Jupiter Cantab. The company was formed by Richard Altwasser and Stephen Vickers, who had been on the design team for the Sinclair ZX Spectrum.

The Jupiter ACE somewhat resembled a ZX81 in a white case, with black rubber keys like the Spectrum. It displayed output on a television, and programs could be saved and loaded on cassette tape, as was standard at that time. The machine came with 3 KB RAM, expandable to 49 K. While it had only one video mode, text only, which displayed 24 rows of 32 columns of characters in black and white, it was possible to display graphics, by redefining the 8x8 pixel bitmap of any of the 128 characters. Like the ZX Spectrum, the machine's audio capabilities were restricted to beeps of programmable frequency and duration, output through a small built-in speaker.

The major difference from the 'introductory computer' that was the ZX81, however, was that the Jupiter ACE's designers, from the outset, intended the machine to be for programmers: the machine came with Forth as its default programming language. Though this gave a great speed advantage over the interpreted BASIC that was used on other machines, it did, along with the meagre sound and graphics capabilities compared to the upcoming competition, keep the ACE squarely in a niche market. Sales of the machine were never very large. The reported number of Ace’s sold before Jupiter Cantab closed for business was around 5,000. Surviving machines are quite uncommon, fetching quite high prices as collectors items.

Jupiter Aces General Specifications.

CPU: Z80A running at 3.25 MHz
Language: O/S: Ace Forth [not a standard fig-Forth or Forth-79].
ROM: 2 x 4kB EPROMs containing the FORTH compiler and editor.
RAM: 3 kB [expandable to 51kB].
Program Storage: 1500 baud cassette tape.
Video Display: 32 x 24 Monochrome Graphics, High Res: 64 x 48, all 128 characters redefinable.
Keyboard: 40 key rubber membrane, with auto-repeat on every key, and two shift keys allow ASCII codes to be produced.
Sound: Single channel buzzer.
Interfaces: TV connector [UHF TV set to Channel 36], Cassette port x2: Ear & Mic, power (9v), two edge connectors: first has a complete address and data lines from the CPU, Second: has data and some selection lines.
Size: 215 x 190 x 30 mm.
Wait: 246 grams.
Documentation: 182 page Users manual.

Ace Forth

Data Structures: Integer, Floating point and String data may be held as constants, variables or arrays with multiple dimensions and mixed data types.
Control Structures: IF-THEN-ELSE, DO-LOOP, BEGIN-WHILE-REPEAT, BEGIN UNTIL, all may be mixed and nested to any depth.
Operators: Mathematical +, —, X, . Logical AND, OR, NOT, XOR. Comparison < , > , =.
Program Editing: FORTH words may be listed, edited and redefined. Comments are preserved when words are compiled.
Word list:
FORTH UFLOAT INT FNEGATE F/ F* F + F— LOAD BVERIFY VERIFY BLOAD BSAVE SAVE LIST EDIT FORGET REDEFINE EXIT . ' ( [ +LOOP LOOP DO UNTIL REPEAT BEGIN THEN ELSE WHILE IF ] LEAVE J I' I DEFINITIONS VOCABULARY IMMEDIATE RUNS> DOES> COMPILER CALL DEFINER ASCII LITERAL CONSTANT VARIABLE ALLOT C, , CREATE : DECIMAL MIN MAX XOR AND OR 2— 1— 2+ 1+ D+ — + DNEGATE NEGATE U/MOD */ * MOD / */MOD /MOD U* D< U< < = 0 0< 0= ABS OUT IN INKEY BEEP PLOT AT F. EMIT CR SPACES SPACE HOLD CLS # #S U. . SIGN #> <# TYPE ROLL PICK OVER ROT ?DUP R> >R ! @ C! C@ SWAP DROP DUP SLOW FAST INVIS VIS CONVERT NUMBER EXECUTE FIND VLIST WORD RETYPE QUERY LINE PAD BASE CURRENT CONTEXT HERE ABORT QUIT OK

Issue 1 Jupiter Ace bought in 1983

A Jupiter Ace chip ID and location.

Just hover your mouse over the parts to find out what they are. On some parts of the image you can click on the link which will give you more info information.

Ace Packaging & Box.

The Jupiter Ace was packed in a polystyrene box with a lid. This housed the machine, manual, power pack, TV cable, cassette Ear+Mic cable and the Ace Demo tape. The poly box was enclosed by a plain brown single wall cardboard box. A sleeve with a few details of the Ace was used to cover the box. These boxes and sleeves are extremely rare as most Aces were properly sold with out the Sleeve or even boxes.