News, Reviews and Letters Index > Jupiter Ace Review in Personal Computing Today

  Jupiter Ace preview in Personal Computing Today December 1982, page 76
THE No 1
David Harwood takes a sneak preview
of the Jupiter Ace.
One of the newest micro computer firms to emerge in recent months is a spin-off from the Clive Sinclair empire, Jupiter Cantab.
The Jupiter Ace micro was the brainchild of two ex-Sinclair Research designers Steven Vickers and Richard Altwasser. The two decided to leave Sinclair and concentrate their efforts on producing their own personal computer.
But don't be fooled into thinking the Ace is an enhancement of, or even an equivalent to the ZX Spectrum. It's not. If you believe this computer to be comparative to the ZX81, you would also be mistaken. The Jupiter Ace is a black and white home computer, priced under £90, which uses the not very well-known, but advantageous programming language FORTH (Fourth General Computer Language).

To give you an idea of size the Jupiter Ace measures 215mm x 190mm with height 35mm. The case unfortunately is of poor quality, white plastic, resembling that of the ZX80 and - wait for it - is held together by those dreaded plastic rivets. The cassette and aerial sockets are on the right and the power supply socket is on the left of the case. This appears to be very neat, although I wish it had an integral power supply, which would be more professional and would certainly be more convenient. The expansion port at the rear brings out every signal you would want, and also it is possible to use the Sinclair RAM pack with slight modification.
The ACE offers no colour facilities, which I feel is a major
I would prefer to pay £20 or so extra to have a full colour facility.
I used the ACE on my Ferguson Colour television and found the white on black display absolutely faultless. It has a proper memory mapped screen with a 32 characters x 24 line display.
There are 28 chips, including a ZX80A CPU running at 3.25 MHz, 8K of ROM and 3K of RAM, which in effect gives a larger capacity than the 3K used on a BASIC computer.
The prototype keyboard consisted of single-solid keys on four sticky strips, poking up through holes in the case. Following a phone call to Steven Vickers I was pleased to learn that this will be changed on the production model. I hope so, as the keys were liable to stick under the top case, causing reptition, as all keys have got an auto-repeat facility. The production model apparently will have a keyboard similar to that of the Spectrum - a one piece rubber mould mounted over a pressure sensitive board.
When the lower copy of the video RAM is addressed you get glitches on the screen, and the wait states are not used, but in the higher copy you get no glitches and the wait states are used. Well, that's about it on the hardware, the only real disappointment being the case, which, although barely adequate, does not affect the operation of the computer.

There is a good syntax-checking system, which will display a question mark if you try to use a word that is not defined or type in something incorrectly such as leaving out a space.
It is initially frustrating that FORTH seems very particular when you omit spaces.
In fact, it will not recognise some commands unless you incorporate a space.
."* * * *" (. is the same as PRINT in BASIC)
will not work, but
." * * * *" where there is a space after the first inverted comma, will - see what I mean?
It can be very annoying when you gaze at the screen for ten minutes, trying to work out "What's wrong?", when you have only left a space out!

Jupiter Ace preview in Personal Computing Today December 1982, page 77
EDITing on the ACE is very simple as all you do is type:-
EDIT name of word
and then alter the contents of. the word by using the cursor and delete keys. A useful function is DELETE LINE (shift 1) which, (Yes!!!) deletes the present line. The INVERSE VIDEO, CAPS LOCK and GRAPHICS are the same as for the Spectrum.
Usually FORTH versions are not capable of Floating Point Arithmetic, but the ACE can handle six significant digits, from 1E + 64 to 1E - 64.
The ACE uses an ASCII character set, incorporating basic graphics, which can be directly accessed from the keyboard. All these characters are stored in RAM and can be redefined, each character being an 8 x 8 array of dots, and is stored as 8 consecutive bytes in the RAM.
FORTH is an interactive language which, unlike BASIC, allows you to define your own commands to meet your specific needs.
FORTH programs are constructed without line numbers as words which are defined in terms of other words, which are in the "Dictionary". (140 words are already defined in the ROM).
If this seems too complicated, let us consider defining a new word.

: ADD 46 + . ;
( : - starts the word definition
ADD - Name of new word
46 - puts 4 and 6 n the stack
+ - adds top two numbers on stack
. - prints the value of the stack)

If we type in ADD, the result of 4 + 6 will be printed out.
We now have a new word - ADD - which now can be used in other words which we can define.

: HEX. 16 BASE C! ADD;

when we type in HEX, the result of ADD will be printed in HEX, as 16 BASE C! changes the system to work in base 16 (HEX).
To learn more about FORTH, see "Getting to know Forth" on Page 44. The FORTH used on the ACE is based on the FORTH 79 standard, but has a number of important improvements, some of which have been mentioned already, e.g. floating point arithmetic, sound, cassette storage, ability to LIST, EDIT and REDEFINE newly defined words. A useful command is VLIST, which lists the complete dictionary on the screen, including the words in the ROM.
There are two possible modes of operation:-
INVIS or VIS - where INVIS stops the copy-up mechanism and suppresses the OK. VIS returns back to normal which is the reverse of INVIS.
FAST or SLOW - where FAST overrides the error checking facility enabling programs to operate faster, SLOW reverts back to normal.
Machine code can be embedden in hexadecimal into FORTH word definitions, and also machine code at an address can be executed by using CALL.
You c PLOT, UNPLOT or OVERPLOT on a grid of 64 x 46 pixels (similar to that on the ZX81).By using the redefined character set you an have a resolution equivalent to 256 x 192 pixels - this is very time consuming as you would need to define 64 characters, with a dot in each square, to obtain
the full advantage of high resolution.
The AT command (seems quite BASIC to me) is used to set the print position and CLS (very BASIC) is used to clear the screen.
Full logical and arithmetical operations are available, manipulating the numbers on the stack. Unfortunately things like SIN, COS, LOG are not available, but they could be defined by you as new words.
After EDITing a word, you can REDEFINE it, (erasing the old definition and putting in the new one). Typing in REDEFINE name can be quite laborious; I would have much preferred to see the question REDEFINE? appear after every EDITing.
There are the usual error codes, which incidentally cannot be suppressed by INVIS.
All in all the ACE version of FORTH is very powerful and is definitely an enhancement of FORTH 79.

Unfortunately there was no documentation available at the time of this review, but there obviously will be a manual, including a step-by-step course in how to program in FORTH.

All in all
Richard Altwasser and Steven Vickers have produced a valuable, versatile computer. The production Jupiter Ace is a very good computer and value for money since it uses the advantageous FORTH. It is a shame that there is no colour, but hopefully someone, somewhere, will produce a colour board.
The FORTH langauge is easily learnt, so the ACE will be of great use in schools and at home. Also, along with extra money and a printer, using the printer interface (and Sinclair's disc drives if they ever materialise) it will be invaluable in an office.
For a 3K Jupiter Ace the price is £89.95. The 16K add on RAM - £30.00 (available later this year) and the PRINTER INTERFACE costs £20.00 (available later this year).
The Jupiter Ace gives you the speed of machine code with the ease of BASIC. Definitely a machine well worth buying.