7 ms·

"Today, the 680x0 is still used by industrial machines, the aircraft industry, cars vendors and fans of retro-computing around the world." it's right there abov

"Today, the 680x0 is still used by industrial machines, the aircraft industry, cars vendors and fans of retro-computing around the world." it's right there above the fold

deleted 5y ago
[deleted]
unixhero 5y ago
A friend and colleague who is a hardcore electrical engineer swears by 68K chips because he almost adores its instruction set. Says coding the assembly on them is superior to any other option for medium to large use cases.
- karmakaze 5y ago
  This is so true, and also the reason for them being less popular. The 6502 wasn't nice like the 6809. Intel ISA is a mess but was simpler in hardware than M68K. "IBM considered the 68000 for the IBM PC but chose the Intel 8088 because the 68000 was not ready; Walden C. Rhines wrote that thus "Motorola, with its superior technology, lost the single most important design contest of the last 50 years" -- Wikipedia Too bad we missed out on M68K IBM PCs, but in the end Macs ended up running x86 (ARM next I suppose).
  - ch_123 5y ago
    Fun fact: IBM released a 68k microcomputer aimed at the laboratory market in 1982. It faded away into obscurity, largely because it was more expensive than the PC, and sold into a role which the PC was more than capable of handling. https://en.wikipedia.org/wiki/IBM_System_9000 https://en.wikipedia.org/wiki/IBM_System_9000
  - jsymolon 5y ago
    The corollary is the same thing happening which caused Apple to move to the Intel CPUs, basically, Motorola being unable to squeeze more performance out of it. On the other hand, with the volume of units that IBM Compatibles had, it may have allowed more resources to push that boundary.
    - rbanffy 5y ago
      > it may have allowed more resources to push that boundary. For a long time, x86 was a joke when compared to PPC. As it was compared to 68K’s right up to the 68040. And, as such things go, it was until it wasn’t. Now, the tables have turned and ARM is proving easier to tweak into higher performance designs.
- phkahler 5y ago
  >> Says coding the assembly on them is superior to any other option for medium to large use cases. I still have a preliminary instruction set manual for the 68000 printed in 1979. At that time I was learning 8080A machine code. When I saw that book the hardware became something I HAD to get my hands on eventually. I finally got to code one in assembly in college and it was every bit as enjoyable as I had imagined. BTW my dad wrote a disassembler for the 8080 in basic, and to simplify everything he rewrote all the mnemonics in a far simpler form than the official syntax from Intel. I still have the 16x16 instruction map. Because of that, the 68000s primary advantage was the increased number of registers and their 32bit size along with some better instructions. The pain of proper 8080 syntax was never a thing for me.
  - cxr 5y ago
    > my dad wrote a disassembler for the 8080 in basic, and to simplify everything he rewrote all the mnemonics in a far simpler form than the official syntax from Intel If you or he still has his notes, would you be able to ZIP them up and upload them to archive.org?
    - phkahler 5y ago
      >> If you or he still has his notes, would you be able to ZIP them up and upload them to archive.org? Not sure why, we were the only 2 people on earth to ever use that. To summarize, he used single letters for verbs and then single letters for register names: a, b,c, d,e, h,l for the 8-bit registers and x,y,z for the 16 bit pairs (b,c) (d,e) (h,l). It turns out you could always figure out some implied stuff. MAY was move a to y, but since A is 8 bits and Y is 16 this meant Y was an address, whereas MAD would be move A to D as an 8 bit register-to-register copy. This lead to all mnemonics being 3 characters or less. There could also be 8 or 16 bit immediate values. The disassembler used a 4 byte decode table - 3 characters and a size (0,1,2) of the immediate data. It was super clean. I'll post is somewhere some day. I still have my Interact computer in its original box waiting to find a nice museum somewhere. And lots of tapes including a bunch of little kid created basic programs. Hard copies of all the "Interaction" newsletters from the local users group too.
- Eric_WVGG 5y ago
  Back in the nineties I heard that, although the SNES had more capabilities in the way of color and 3D, "hard core" devs like David Perry could get better raw performance out of the 68000-based Sega Genesis for similar reasons.
  - cmrdporcupine 5y ago
    Clock for clock a 6502/65816 would outperform a 68000 at raw byte moving and responding to interrupts, but the 68k would smoke it on anything involving heavy integer calculations especially 16-bit or 32-bit integers or anything involving longer words. So as games got more complex, and clock rates higher, a 68k would definitely outperform. The 6502 is very cycle efficient and its ridiculously small register makes it fast to respond to interrupts, which I guess in a game machine is a good thing. But machines like the Amiga, Sharp X68000, and lots of arcade games packed in a bunch of custom video hardware too.
    - rbanffy 5y ago
      The 68000, with its neat ISA, linear address space and large register set, is much easier to program than a 6502/65816. All other things (SDKs, dev hardware) being equal, will result in more, better games hitting the market at a faster cadence.
- cmrdporcupine 5y ago
  The 68k has an excellent instruction set but imho it suffers from two things: a) It's big-endian. This is a bit of a religious thing, but in the end little-endian won out, and probably for good reasons. It's arguably easier to read a big-endian hexdump but harder for the processor itself to manage and harder for some bit twiddling. b) Separate "data" and "address" register sets. Awkward to program, and makes the instruction set more complicated. Looking back, the similar but not nearly as successful NS320xx architecture was better. Atari apparently even prototyped it for use in what became the (68k based) Atari ST, but the first chips produced in that series were too buggy. Both the 68k series and the NS32k series were heavily 'inspired' by the VAX. One thing that makes the 68k cool is that it's about as "retro" of an architecture as you can get that still supports a modern C/C++ toolchain. GCC still (mostly) supports it.
  - kabdib 5y ago
    I worked on the ST and helped evaluate the NS32032/32016. We started counting clock cycles for various operations and got some bad vibes, and then we started finding out about chip bugs (definitely not pretty, and National was coy about them and just said stuff like "we're working on it"), we so decided to use the 68K. The NS parts were really a due-diligence affair, and we looked at them just to make sure we weren't missing out on something really great (we weren't). Definitely a prettier architecture than the 68K, with better toolchains and development support at the time. Didn't make up for the bad, though.
    - cmrdporcupine 5y ago
      Thanks, I always appreciate it when you chime in. Looking back, did Atari Corp actually build any hardware (prototype, wirewrap, etc.) with the 320xx? Or was it just evaluation from the POV of reading datasheets and the like? I've heard conflicting stories around this. That and the story about Atari talking with Microsoft about an early version of Windows for their hardware.
      - kabdib 5y ago
        Whether or not anyone wire-wrapped a board (pretty sure no one did), we didn't write a single line of code for the National parts. There were a number of visits by National sales reps and they dropped a lot of documentation on us, though. We were generally doubtful that the chip would be fast enough, and needed to make a processor decision very quickly; in late July 1984 we were talking about it, and I don't recall anything past August or so. By October the software folks were mostly in Monterey with a bunch of 68K-based systems. Another factor in the 68K's favor was that it was pretty easy to buy off-the-shelf 68K-based workstations (e.g., Motorola VME-10, the Apple Lisa), which let us do 4-5 months of software development while waiting for the actual ST hardware.
- zozbot234 5y ago
  The 68k insn set is a rather traditional CISC architecture, there's not much that makes it "superior" to modern designs. It's comparatively simple because it never really got extended beyond recognition as other architectures have been, but other than that I can't see any reason to recommend it.
duskwuff 5y ago
That statement might have been true when it was first written. It isn't anymore -- nobody is seriously using the 68000 in new hardware designs. Parts availability is limited, and is only going to get more so in the future.
deleted 5y ago
[deleted]

"Today, the 680x0 is still used by industrial machines, the aircraft industry, cars vendors and fans of retro-computing around the world." it's right there above the fold

deleted 5y ago

[deleted]

unixhero 5y ago

A friend and colleague who is a hardcore electrical engineer swears by 68K chips because he almost adores its instruction set. Says coding the assembly on them is superior to any other option for medium to large use cases.

karmakaze 5y ago
This is so true, and also the reason for them being less popular. The 6502 wasn't nice like the 6809. Intel ISA is a mess but was simpler in hardware than M68K. "IBM considered the 68000 for the IBM PC but chose the Intel 8088 because the 68000 was not ready; Walden C. Rhines wrote that thus "Motorola, with its superior technology, lost the single most important design contest of the last 50 years" -- Wikipedia Too bad we missed out on M68K IBM PCs, but in the end Macs ended up running x86 (ARM next I suppose).
- ch_123 5y ago
  Fun fact: IBM released a 68k microcomputer aimed at the laboratory market in 1982. It faded away into obscurity, largely because it was more expensive than the PC, and sold into a role which the PC was more than capable of handling. https://en.wikipedia.org/wiki/IBM_System_9000 https://en.wikipedia.org/wiki/IBM_System_9000
- jsymolon 5y ago
  The corollary is the same thing happening which caused Apple to move to the Intel CPUs, basically, Motorola being unable to squeeze more performance out of it. On the other hand, with the volume of units that IBM Compatibles had, it may have allowed more resources to push that boundary.
  - rbanffy 5y ago
    > it may have allowed more resources to push that boundary. For a long time, x86 was a joke when compared to PPC. As it was compared to 68K’s right up to the 68040. And, as such things go, it was until it wasn’t. Now, the tables have turned and ARM is proving easier to tweak into higher performance designs.
phkahler 5y ago
>> Says coding the assembly on them is superior to any other option for medium to large use cases. I still have a preliminary instruction set manual for the 68000 printed in 1979. At that time I was learning 8080A machine code. When I saw that book the hardware became something I HAD to get my hands on eventually. I finally got to code one in assembly in college and it was every bit as enjoyable as I had imagined. BTW my dad wrote a disassembler for the 8080 in basic, and to simplify everything he rewrote all the mnemonics in a far simpler form than the official syntax from Intel. I still have the 16x16 instruction map. Because of that, the 68000s primary advantage was the increased number of registers and their 32bit size along with some better instructions. The pain of proper 8080 syntax was never a thing for me.
- cxr 5y ago
  > my dad wrote a disassembler for the 8080 in basic, and to simplify everything he rewrote all the mnemonics in a far simpler form than the official syntax from Intel If you or he still has his notes, would you be able to ZIP them up and upload them to archive.org?
  - phkahler 5y ago
    >> If you or he still has his notes, would you be able to ZIP them up and upload them to archive.org? Not sure why, we were the only 2 people on earth to ever use that. To summarize, he used single letters for verbs and then single letters for register names: a, b,c, d,e, h,l for the 8-bit registers and x,y,z for the 16 bit pairs (b,c) (d,e) (h,l). It turns out you could always figure out some implied stuff. MAY was move a to y, but since A is 8 bits and Y is 16 this meant Y was an address, whereas MAD would be move A to D as an 8 bit register-to-register copy. This lead to all mnemonics being 3 characters or less. There could also be 8 or 16 bit immediate values. The disassembler used a 4 byte decode table - 3 characters and a size (0,1,2) of the immediate data. It was super clean. I'll post is somewhere some day. I still have my Interact computer in its original box waiting to find a nice museum somewhere. And lots of tapes including a bunch of little kid created basic programs. Hard copies of all the "Interaction" newsletters from the local users group too.
Eric_WVGG 5y ago
Back in the nineties I heard that, although the SNES had more capabilities in the way of color and 3D, "hard core" devs like David Perry could get better raw performance out of the 68000-based Sega Genesis for similar reasons.
- cmrdporcupine 5y ago
  Clock for clock a 6502/65816 would outperform a 68000 at raw byte moving and responding to interrupts, but the 68k would smoke it on anything involving heavy integer calculations especially 16-bit or 32-bit integers or anything involving longer words. So as games got more complex, and clock rates higher, a 68k would definitely outperform. The 6502 is very cycle efficient and its ridiculously small register makes it fast to respond to interrupts, which I guess in a game machine is a good thing. But machines like the Amiga, Sharp X68000, and lots of arcade games packed in a bunch of custom video hardware too.
  - rbanffy 5y ago
    The 68000, with its neat ISA, linear address space and large register set, is much easier to program than a 6502/65816. All other things (SDKs, dev hardware) being equal, will result in more, better games hitting the market at a faster cadence.
cmrdporcupine 5y ago
The 68k has an excellent instruction set but imho it suffers from two things: a) It's big-endian. This is a bit of a religious thing, but in the end little-endian won out, and probably for good reasons. It's arguably easier to read a big-endian hexdump but harder for the processor itself to manage and harder for some bit twiddling. b) Separate "data" and "address" register sets. Awkward to program, and makes the instruction set more complicated. Looking back, the similar but not nearly as successful NS320xx architecture was better. Atari apparently even prototyped it for use in what became the (68k based) Atari ST, but the first chips produced in that series were too buggy. Both the 68k series and the NS32k series were heavily 'inspired' by the VAX. One thing that makes the 68k cool is that it's about as "retro" of an architecture as you can get that still supports a modern C/C++ toolchain. GCC still (mostly) supports it.
- kabdib 5y ago
  I worked on the ST and helped evaluate the NS32032/32016. We started counting clock cycles for various operations and got some bad vibes, and then we started finding out about chip bugs (definitely not pretty, and National was coy about them and just said stuff like "we're working on it"), we so decided to use the 68K. The NS parts were really a due-diligence affair, and we looked at them just to make sure we weren't missing out on something really great (we weren't). Definitely a prettier architecture than the 68K, with better toolchains and development support at the time. Didn't make up for the bad, though.
  - cmrdporcupine 5y ago
    Thanks, I always appreciate it when you chime in. Looking back, did Atari Corp actually build any hardware (prototype, wirewrap, etc.) with the 320xx? Or was it just evaluation from the POV of reading datasheets and the like? I've heard conflicting stories around this. That and the story about Atari talking with Microsoft about an early version of Windows for their hardware.
    - kabdib 5y ago
      Whether or not anyone wire-wrapped a board (pretty sure no one did), we didn't write a single line of code for the National parts. There were a number of visits by National sales reps and they dropped a lot of documentation on us, though. We were generally doubtful that the chip would be fast enough, and needed to make a processor decision very quickly; in late July 1984 we were talking about it, and I don't recall anything past August or so. By October the software folks were mostly in Monterey with a bunch of 68K-based systems. Another factor in the 68K's favor was that it was pretty easy to buy off-the-shelf 68K-based workstations (e.g., Motorola VME-10, the Apple Lisa), which let us do 4-5 months of software development while waiting for the actual ST hardware.
zozbot234 5y ago
The 68k insn set is a rather traditional CISC architecture, there's not much that makes it "superior" to modern designs. It's comparatively simple because it never really got extended beyond recognition as other architectures have been, but other than that I can't see any reason to recommend it.

duskwuff 5y ago

That statement might have been true when it was first written. It isn't anymore -- nobody is seriously using the 68000 in new hardware designs. Parts availability is limited, and is only going to get more so in the future.

deleted 5y ago

[deleted]