4 ms·

Oooh. 6809 resurrection project. I studied that arch obsessively when I was a kid with a Tandy Color Computer.

PaulHoule 2y ago
Funny I noticed this one when I was reading a paper about people using an OS-9 variant together with the Turbo9. See https://www.mdpi.com/2079-9292/13/10/1978 https://www.mdpi.com/2079-9292/13/10/1978 I had a Coco 1 and a Coco 3, with the OS-9 operating system you could run C and Pascal compilers as well as use BASIC09 which was like a modern bytecode interpreted language (Python). The 6809 stands out because it was designed to support compiled languages, shared libraries and such. It not only had the right addressing modes but it had just enough registers that code generation was straightforward. When I replaced my Coco3 with a 286 machine I switched to hardware that was more than an order of magnitude faster but MS-DOS was a big step back from OS-9. Lately I have been obsessed with the lost 24-bit generation of micros and was quite delighted to discover the eZ80, would be nice to see the 6809 follow the same route but Motorola was too committed to the ultimately doomed 68k.
- cmrdporcupine 2y ago
  I mean, was 68k really "doomed"? Millions of machines shipped with it, it went through like 6 generations (and then ColdFire), and it's still used in military hardware with new chips made for that industry, and its existence heavily influenced everything about the Unix environments & protocols we use today. It was a great ISA (though clearly completely different from the 6809), and these days big endian looks like a serious anachronism.
  - PaulHoule 2y ago
    Wasn't it the VAX that set the precedent for all the "32-bit" machines ever since? Every company that invested in it, however, had to either go out of business or switch to another architecture, usually the first. Apple and Sun Microsystems survived. Fragmentation, with the Apple Macintosh, Amiga, Atari ST, Sinclair QL, etc. (all similar machines that struggled with cost-performance tradeoffs in different ways), didn't help. The BBC Micro developers probably had more space to really think about how to make a home computer and looked at many architectures and came to the conclusion that the 68k line punched below its weight. People in the early 1980s didn't see that one of the greatest rugpulls in computing was coming and were blindsided by IBM "doing it again" by maintaining long-term software compatibility with the 8088 and derivatives the way they did for the old 360... Companies that invested in the x86 didn't regret it, though many of them were crushed by an increasingly competitive market.
    - cmrdporcupine 2y ago
      I absolutely agree that Motorola fucked up bigtime with the 68k->88k->PPC transition. They listened to the pundits who said the CISC ISA couldn't scale, and then Intel proved that (mostly) wrong but it was too late for 68k/ColdFire then. The rug-pulling actually is probably in large part responsible for both Atari and Commodore just packing it in, and led to Apple being in the wilderness for a decade as they did the first of 3 ISA transitions for the Mac. Also yes the 68k was clearly a dog when it came to interrupt responsiveness and made no sense in home computers or video games, at least not until the '020. It was meant to be a bargain VAX. And that's why I say it was influential. A whole generation (X) of us grew up who could never hope (or care) to touch a VAX, but we had Atari STs, Amigas, etc at home, and were shelling into SunOS 68k boxes for fun or school etc. It lasted quite a while after VAX was a done deal, too. To me 68k was the Unix workstation and hobbyist market and defined 32-bit ISAs as well. I never touched an x86 until I could run Linux on it. I've never learned or written x86 assembly seriously in my entire career despite writing (and enjoying) 6502 68k, ARM, MIPS, RISC-V, others Outside of the UK, ARM didn't play a role except for in some embedded stuff. Obviously that changed :-)
      - KerrAvon 2y ago
        We need to remember that everyone -- not just Motorola -- thought CISC was a dead-end by the late 1980's. Even Intel! And we also need to acknowledge that everyone was RIGHT! Intel ultimately threw billions into keeping x86 competitive, and they seem to have finally hit the wall now with performance per watt measures, which is what cost them Apple's business and is now driving Microsoft to ARM.
        snvzz 2y ago
        >And we also need to acknowledge that everyone was RIGHT! And x86 will, too, be replaced.
      - snvzz 2y ago
        >Also yes the 68k was clearly a dog when it came to interrupt responsiveness and made no sense in home computers or video games, at least not until the '020. In what world? The interrupts were very fast, taking just a few cycles, and the behavior was deterministic. This is why they were popular in realtime applications, and remained so for decades. Back in the day, they were famously used in e.g. the Eurofighter Typhoon.
  - Tor3 2y ago
    It was simply phased out at some point, like so many other processors. I think it's wrong to say it was "doomed". For one of the minicomputer systems I worked with until around 1995 all the interface boards used m68k CPUs and were running their own little operating systems. This made the whole mini quite efficient - all the intelligence in the peripherals meant that a lot of data transfers could be performed independently of the main CPU.
- shrubble 2y ago
  Funny fact: Motorola didn't ship 68040 CPUs over 40Mhz because they didn't think customers would tolerate even a small heat sink and fan combination being required for the chip. *looks at massive heat sink and fan on my desktop system...
- anonymousiam 2y ago
  About 35 years ago, I did some embedded development on a 68k platform running OS-9 (ported to 68k from 6809). I was really impressed with the POSIX-like environment, but thoroughly disgusted with the very poor documentation. I found that I had to write a lot of stub code to fully determine and understand the behavior of the system calls. This was after I had purchased and fully digested the only documentation I could find: "OS-9 Insights" https://www.amazon.com/OS-9-insights-advanced-programmers-guide/dp/0918035015 https://www.amazon.com/OS-9-insights-advanced-programmers-gu...
mordechai9000 2y ago
Me too! I remember laboriously typing in the demo program from "TRS-80 Color Computer Assembly Language Programming" and watching it bubble sort the text on screen by directly accessing video memory.

Funny I noticed this one when I was reading a paper about people using an OS-9 variant together with the Turbo9. See https://www.mdpi.com/2079-9292/13/10/1978 https://www.mdpi.com/2079-9292/13/10/1978 I had a Coco 1 and a Coco 3, with the OS-9 operating system you could run C and Pascal compilers as well as use BASIC09 which was like a modern bytecode interpreted language (Python). The 6809 stands out because it was designed to support compiled languages, shared libraries and such. It not only had the right addressing modes but it had just enough registers that code generation was straightforward. When I replaced my Coco3 with a 286 machine I switched to hardware that was more than an order of magnitude faster but MS-DOS was a big step back from OS-9. Lately I have been obsessed with the lost 24-bit generation of micros and was quite delighted to discover the eZ80, would be nice to see the 6809 follow the same route but Motorola was too committed to the ultimately doomed 68k.

cmrdporcupine 2y ago
I mean, was 68k really "doomed"? Millions of machines shipped with it, it went through like 6 generations (and then ColdFire), and it's still used in military hardware with new chips made for that industry, and its existence heavily influenced everything about the Unix environments & protocols we use today. It was a great ISA (though clearly completely different from the 6809), and these days big endian looks like a serious anachronism.
- PaulHoule 2y ago
  Wasn't it the VAX that set the precedent for all the "32-bit" machines ever since? Every company that invested in it, however, had to either go out of business or switch to another architecture, usually the first. Apple and Sun Microsystems survived. Fragmentation, with the Apple Macintosh, Amiga, Atari ST, Sinclair QL, etc. (all similar machines that struggled with cost-performance tradeoffs in different ways), didn't help. The BBC Micro developers probably had more space to really think about how to make a home computer and looked at many architectures and came to the conclusion that the 68k line punched below its weight. People in the early 1980s didn't see that one of the greatest rugpulls in computing was coming and were blindsided by IBM "doing it again" by maintaining long-term software compatibility with the 8088 and derivatives the way they did for the old 360... Companies that invested in the x86 didn't regret it, though many of them were crushed by an increasingly competitive market.
  - cmrdporcupine 2y ago
    I absolutely agree that Motorola fucked up bigtime with the 68k->88k->PPC transition. They listened to the pundits who said the CISC ISA couldn't scale, and then Intel proved that (mostly) wrong but it was too late for 68k/ColdFire then. The rug-pulling actually is probably in large part responsible for both Atari and Commodore just packing it in, and led to Apple being in the wilderness for a decade as they did the first of 3 ISA transitions for the Mac. Also yes the 68k was clearly a dog when it came to interrupt responsiveness and made no sense in home computers or video games, at least not until the '020. It was meant to be a bargain VAX. And that's why I say it was influential. A whole generation (X) of us grew up who could never hope (or care) to touch a VAX, but we had Atari STs, Amigas, etc at home, and were shelling into SunOS 68k boxes for fun or school etc. It lasted quite a while after VAX was a done deal, too. To me 68k was the Unix workstation and hobbyist market and defined 32-bit ISAs as well. I never touched an x86 until I could run Linux on it. I've never learned or written x86 assembly seriously in my entire career despite writing (and enjoying) 6502 68k, ARM, MIPS, RISC-V, others Outside of the UK, ARM didn't play a role except for in some embedded stuff. Obviously that changed :-)
    - KerrAvon 2y ago
      We need to remember that everyone -- not just Motorola -- thought CISC was a dead-end by the late 1980's. Even Intel! And we also need to acknowledge that everyone was RIGHT! Intel ultimately threw billions into keeping x86 competitive, and they seem to have finally hit the wall now with performance per watt measures, which is what cost them Apple's business and is now driving Microsoft to ARM.
      - snvzz 2y ago
        >And we also need to acknowledge that everyone was RIGHT! And x86 will, too, be replaced.
    - snvzz 2y ago
      >Also yes the 68k was clearly a dog when it came to interrupt responsiveness and made no sense in home computers or video games, at least not until the '020. In what world? The interrupts were very fast, taking just a few cycles, and the behavior was deterministic. This is why they were popular in realtime applications, and remained so for decades. Back in the day, they were famously used in e.g. the Eurofighter Typhoon.
- Tor3 2y ago
  It was simply phased out at some point, like so many other processors. I think it's wrong to say it was "doomed". For one of the minicomputer systems I worked with until around 1995 all the interface boards used m68k CPUs and were running their own little operating systems. This made the whole mini quite efficient - all the intelligence in the peripherals meant that a lot of data transfers could be performed independently of the main CPU.
shrubble 2y ago
Funny fact: Motorola didn't ship 68040 CPUs over 40Mhz because they didn't think customers would tolerate even a small heat sink and fan combination being required for the chip. *looks at massive heat sink and fan on my desktop system...
anonymousiam 2y ago
About 35 years ago, I did some embedded development on a 68k platform running OS-9 (ported to 68k from 6809). I was really impressed with the POSIX-like environment, but thoroughly disgusted with the very poor documentation. I found that I had to write a lot of stub code to fully determine and understand the behavior of the system calls. This was after I had purchased and fully digested the only documentation I could find: "OS-9 Insights" https://www.amazon.com/OS-9-insights-advanced-programmers-guide/dp/0918035015 https://www.amazon.com/OS-9-insights-advanced-programmers-gu...

mordechai9000 2y ago

Me too! I remember laboriously typing in the demo program from "TRS-80 Color Computer Assembly Language Programming" and watching it bubble sort the text on screen by directly accessing video memory.