Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

The Curious Case of Jupiter Ace

nemanjatrifunovic.substack.com

Post reply on HN
Print view View original

11–18 of 18 posts

Re: The Curious Case of Jupiter Ace

#11

Post by astrobe_ »

mhandley wrote: post #4

I had one of the early Jupiter Aces - the circuit board said something like v1.00 - and it had some added soldered wires on the board, correcting some errors, but it worked well enough. Forth was definitely what attracted me to it - I was frustrated with Basic on my Sinclair XZ81, and Forth seemed like a big step forward. And I think it was. I was 14 or 15 at the time. The first summer I wrote a whole load of games,…

Meanwhile, I managed to roast an EEPROM that contained a assembler/disassembler for Z80 by pluging it the wrong way in a weird expansion board for a CPC 6128. It was an expensive Xmas present, I almost passed out when I realized my mistake. I don't remember how old I was when it happened, but definitely not enough to RTFM cautiously.

So I had to stick with Basic until I finally got my first PC. It was the time when one could order floppy disks preloaded with "sharewares" you selected from a catalog. The first and only I order contained A86/D86 [2] and PygmyForth [1]. I picked up a Forth because I saw ads in magazines for Forth systems featuring multitasking and other wonderful things.

I spent a lot of time with those two, and eventually started to program my own Forth interpreter as any sane person should do... I ended up writing a minimal assembler with the help of A86's extensive manual in order to be able to boot my system from a floppy, modify its source with a block editor, and recompile it from scratch, boot sector included. It's sole use ever was to prove myself I could do those "difficult" things.

[1] https://pygmy.utoh.org/pygmyforthmanual.html [2] http://eji.com/a86/

Re: The Curious Case of Jupiter Ace

#12

Post by wduquette »

I suspect that the Ace would have failed quickly in the market, at least as an end-user machine, even if it had matched the ZX Spectrum for graphics and memory. It was extremely difficult to corrupt memory in BASIC unless one got too eager with POKE; but every memory set in Forth is basically a POKE.

Might have been a popular hobbyist machine, though.

Re: The Curious Case of Jupiter Ace

#13

Post by satiated_grue »

PaulHoule wrote: post #10

The earliest home computers had tiny amounts of memory: my TRS-80 Color Computer started out with 4K of RAM and BASIC in ROM although within a few years I had it filled out with 64K of RAM. There weren't a lot of languages that would fit in 4K, but they included BASIC, FORTH and assembler (like the actual assembler.) [1] My FORTH experience with that was writing a subroutine-threaded FORTH for the 6809 under the OS-9…

The 6502's lack of registers is one point of view.

Another point of view is that the zero page provides 256 registers:

https://spectrum.ieee.org/q-a-with-co-creator-of-the-6502-pr...

"[Bill Mensch]:Rod Orgill and I had completed the designs of a few microprocessors before the 6501/6502. In other words, Rod and I already knew what was successful in an instruction set. And lower cost was key. So we looked at what instructions we really needed. And we figured out how to have addressable registers by using zero page [the first 256 bytes in RAM]. So you can have one byte for the op code and one byte for the address, and [the code is compact and fast]. There are limitations, but compared to other processors, zero page was a big deal."

https://news.ycombinator.com/item?id=38627821

http://forum.6502.org/viewtopic.php?f=2&t=7304

Re: The Curious Case of Jupiter Ace

#14

Post by renewedrebecca »

satiated_grue wrote: post #13
PaulHoule wrote: post #10

The earliest home computers had tiny amounts of memory: my TRS-80 Color Computer started out with 4K of RAM and BASIC in ROM although within a few years I had it filled out with 64K of RAM. There weren't a lot of languages that would fit in 4K, but they included BASIC, FORTH and assembler (like the actual assembler.) [1] My FORTH experience with that was writing a subroutine-threaded FORTH for the 6809 under the OS-9…

The 6502's lack of registers is one point of view. Another point of view is that the zero page provides 256 registers: https://spectrum.ieee.org/q-a-with-co-creator-of-the-6502-pr... "[Bill Mensch]:Rod Orgill and I had completed the designs of a few microprocessors before the 6501/6502. In other words, Rod and I already knew what was successful in an instruction set. And lower cost was key. So we looked at what instr…

I see this idea a lot, but I don't really buy it. I've coded in 6502 assembly for years, and the zero page is not register-like at all.

Best thing you can say about zero page is that it only requires one read cycle to fetch a value from. (Or one write cycle to store a value to it.)

Why ZP isn't like registers: You can't do register operations with it. For example, you can do this with the accumulator:

LDA #03 ; load immediate value of 3. STA $c000 ; store it at $c000.

or

LDA $1004 ; load a value from $1004. ADC $4000 ; add the value stored at $4000. STA $4001 ; store to $4001.

You can't do this at all with a zero page address. You have to go through an actual register first.

Re: The Curious Case of Jupiter Ace

#15

Post by pjmlp »

wduquette wrote: post #12

I suspect that the Ace would have failed quickly in the market, at least as an end-user machine, even if it had matched the ZX Spectrum for graphics and memory. It was extremely difficult to corrupt memory in BASIC unless one got too eager with POKE; but every memory set in Forth is basically a POKE. Might have been a popular hobbyist machine, though.

There were extensions for the Speccy to use Forth instead of BASIC, I remember such ads.

Don't remember if it was ROM replacements, or plugged into extension port on the back.

Re: The Curious Case of Jupiter Ace

#16

Post by SanjayMehta »

mhandley wrote: post #4

I had one of the early Jupiter Aces - the circuit board said something like v1.00 - and it had some added soldered wires on the board, correcting some errors, but it worked well enough. Forth was definitely what attracted me to it - I was frustrated with Basic on my Sinclair XZ81, and Forth seemed like a big step forward. And I think it was. I was 14 or 15 at the time. The first summer I wrote a whole load of games,…

I think I saw a black and white photograph of your micro mouse in British magazine back then. I used to subscribe to “Your Computer” to feed my ZX Spectrum habit.

Re: The Curious Case of Jupiter Ace

#17

Post by pjmlp »

astrobe_ wrote: post #11
mhandley wrote: post #4

I had one of the early Jupiter Aces - the circuit board said something like v1.00 - and it had some added soldered wires on the board, correcting some errors, but it worked well enough. Forth was definitely what attracted me to it - I was frustrated with Basic on my Sinclair XZ81, and Forth seemed like a big step forward. And I think it was. I was 14 or 15 at the time. The first summer I wrote a whole load of games,…

Meanwhile, I managed to roast an EEPROM that contained a assembler/disassembler for Z80 by pluging it the wrong way in a weird expansion board for a CPC 6128. It was an expensive Xmas present, I almost passed out when I realized my mistake. I don't remember how old I was when it happened, but definitely not enough to RTFM cautiously. So I had to stick with Basic until I finally got my first PC. It was the time when o…

Given how much any kind of peripheral used to cost in the 8 bit home computer days I imagine how much that hurted.

All my stuff on those days were equally Christmas or birthdays gifts, or having to save up during months.

My first Assemblers were a mix of hand translating opcodes into DATA code blocks, and then I upgraded to hexdump editors, never managed to acquire a proper 8 bit Assembler, and during the first year of PC, MS-DOS debug was the only way.

My first Assembler was also A86/D86 shipped on a 5 inch floppy in a book I think from Sybex, no longer certain.

Re: The Curious Case of Jupiter Ace

#18

Post by tabemann »

I largely agree with this article's assessment. As a machine the Jupiter Ace was simply too little, too late. Had it been more powerful, with more RAM and better graphics, it could have given the Speccy a run for its money, but rather it was already obsolete, being positioned as a competitor for the ZX81 when the ZX81 was already very dated and where it had little in the way of a cost advantage over the far superior Speccy. Running BASIC rather than Forth would not have saved the Jupiter Ace, and rather if the Jupiter Ace had had specs that compared with those of the Speccy it could have given it a run for its money.
Post reply on HN