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Comment by ralphc | Hacker News Reader

I'm a vintage computer collector and the Jupiter Ace would be the holy grail of my collection. Has anyone seen one in real life?

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A Jupiter Ace was my second computer, when I was 14 or 15, after a Sinclair ZX81. Great little computer, but compared to the Spectrum that came out around the same time, it had a worse keyboard, only black and white graphics and 3KB of RAM. Because it used Forth, you could do quite a lot in 3KB, but it was still a bit limiting. I think mine was a very early one, because it had some added soldered wires on the board, correcting some errors.

Mine got modified quite a bit over the next couple of years. Extra RAM. Some dumpster diving got me several keypads with good quality keys. I took them apart and made a proper keyboard to replace the original dead rubber monstrosity.

I made a parallel I/O port out of TTL logic and veroboard. And then temporarily my Ace rode about on the top of a fairly flaky micromouse exploring mazes. It didn't win any prizes but it did get me an A in O-level Technology.

My school was throwing out an old teletype, so I scavenged that. Then I modified the parallel I/O port to output +/- 12V on one pin, and wrote software to bit-bang RS232 at 110 baud. Back before the Internet, just finding the specs for RS232 was not so simple - our local library was a bit limited in that way - but I got there in the end. A lot of guesswork and trial and error. I don't think anyone made a printer for the Ace, so I may have had the only one. Being able to print code listings really helped.

The first summer I wrote a whole load of games, mostly in Forth, but sometimes Forth just wasn't fast enough. I got a copy of "Mastering Machine Code on Your ZX81", and learned Z80 machine code. If there was an assembler available, I didn't have it, so this was all hand-assembled. Getting jumps right was a total pain, as was debugging. Generally, it either worked first time, or you started from scratch again. Usually I got there in the end.

I sold those games through a ad in "Your Computer" magazine, and earned back the price of the computer several times. But recording and shipping tapes one at a time got tedious really fast, so I didn't take that any further.

Somewhere over the years, with my parents moving house multiple times, the Ace disappeared. Many years later, I found one on Ebay, and still have it. But somehow I never fell back in love with it - it just wasn't as good as I remembered my one rather non-stock one being at that formative time in my life.

Oh man, those were fun times. I started with a Model 15 TTY (for ham radio). When I got my first 8080 machine (statuc RAM was an expensive extra), I learned a lot by making a PC board to convert 45bps (5-bit characters) to 110bps Baudot (using 2 crystals). Then teaching the 8080 to table-convert baudot to ASCII (from a 'ring buffer' filled using interrupts).

The good old days, before layers of 'protection' got baked in (Apple II vs Mac).

There's one in the Cambridge computer museum: https://www.computinghistory.org.uk/det/1332/Jupiter-Ace/

Steve Vickers, one of the founders of Jupiter Cantab, was my university lecturer back in the 90s. He taught a very obscure course in mathematical structures, and in a sense was both the first and last (a decade and a half later) to teach me computer science. Previous comments: https://news.ycombinator.com/item?id=23760382 https://news.ycombinator.com/item?id=26375986

I've seen one once at a HamFest or something.

There are kits out there to make your own though:

https://www.tfw8b.com/product/minstrel-4d-turbo-jupiter-ace-...

several on ebay, here's one:

https://www.ebay.com/itm/115272079823?itmmeta=01J10WB15JY1KF...

For only 1600 pounds.

Do you have any OpenBoot/OpenFirmware machines like the Sun4 or early SPARCstations? I was wondering what they were like as pure Forth machines.

I'm not a Forth programmer, but I used to be a Sun sysadmin. From what I recall, the Forth code on a SPARCstation is interpreted and pretty slow.

These docs support that: https://docs.oracle.com/cd/E19455-01/816-1177-10/816-1177-10...

The system supports FCode, which is processor-independent byte code. This allows expansion devices (like a card or peripheral) to bring with them their own platform-independent device drivers, which is pretty cool. So you could make a disk controller card and then any system that you plug it into could boot off it, no matter the CPU architecture.

Anyway, the point is, since it was mainly used for booting and diagnostics, I don't think they put much effort into performance. For it to be an actually good Forth environment, I think you'd want to have some way to run Forth programs as native code, either by adding the option to JIT the FCode instead of interpreting it or by adding a compiler that compiles Forth source to native.

Also, I believe the old PowerPC Macs (like G3, G4, and G5) used Open Firmware, so if you wanted this Forth experience, you have that option in addition to Sun workstations.

> Also, I believe the old PowerPC Macs (like G3, G4, and G5) used Open Firmware, so if you wanted this Forth experience, you have that option in addition to Sun workstations.

So did the OLPC-1 where the non-FOSS nature of "Open" Firmware was a bit alien.

The text mode on the framebuffer was terrible on most machines, too.

Still, stop-a and then e.g. 3719 824 + 53 * . when you needed a little bit of arithmetic help was always a possibility ;)

The G4 did indeed support Open Firmware: I had an MDD.

Mitch Bradley was the author of a great deal of that Forth; his CForth is on GitHub : https://github.com/MitchBradley/cforth

(It might be easier than finding an old Sun machine)

At my local fine-fare (80s uk superstore) they sold computers in a 'concession' stand.

They sold Jupiter Aces. Wish I had the money back then to get one!

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