4 ms·

CMOC – a 6809-generating cross-compiler for a subset of the C language

37 points by philonoist 5y ago

johndoe0815 5y ago
My favourite 8 bit CPU! :) There’s also a 6809 backend for gcc - https://gitlab.com/dfffffff/gcc6809 https://gitlab.com/dfffffff/gcc6809
- zabzonk 5y ago
  > My favourite 8 bit CPU! Mine too, on a Dragon 32. Such an elegant instruction set! I wrote about a half of a simulator for it in some years later in C++, but never got the whole thing working.
apricot 5y ago
I love the fact that it comes with a "CMOC for Basic Programmers" manual. http://perso.b2b2c.ca/~sarrazip/dev/cmoc-for-basic-programmers.html http://perso.b2b2c.ca/~sarrazip/dev/cmoc-for-basic-programme...
- vaxman 5y ago
  Because it also targets the CoCo (Tandy's Color Computer sold through the defunct Radio Shack retail chain). Yes, 6809 was an amazing microprocessor. It was doomed by the vaporware-ish Zilog Z8000 and the long delayed Motorola 68000 (the combined effect was to keep potential manufacturers of new 6809-based SBCs waiting on the sidelines for the new 16-bit generation microprocessors, while their much older 6502/8085/Z80/TMS9900 based boards skyrocketed in popularity...making it increasingly difficult to transition them to the far superior, but slightly software incompatible, 6809 microprocessors. Someone even had to eventually make a65C816 to keep the 6502 users on life support. The delayed 68000-series machines (which, like 6809, also broke software compatibility, but offered superior clock rates and 16-bit computing) came in too hot (the high-end workstations like Apple Lisa, SAGE, etc. followed by Mac, Amiga and Atari's knockoff of it.) This temporary market phenom also was probably the driving force behind Acorn/ARM, which is finally "taking over the game" (33 years later lol) after having been put on steroids by a few chip designers (first DEC with the StrongArm, now Apple with M1 Ultra, soon Ampere with the Siryn).
Annatar 5y ago
No full libc or float / double support - what's the point then?
- glonq 5y ago
  Yeah no SIMD either! /s
  - Annatar 5y ago
    The MOS 6502 processor has only three 8-bit registers and only supports 8-bit integer arithmetic, so implementing one's own multiple precision floating point arithmetic is a major pain in the ass. If the C compiler doesn't provide the float and double data types, which are basic C datatypes, this means that a lot of modern software written in C cannot be compiled to 6502 machine code, and that one must write one's own arithmetic routines, at which point one is compelled to ask oneself: what's the benefit of the aforementioned C compiler when one would not be able to compile existing C software with it?

37 points by philonoist 5y ago

My favourite 8 bit CPU! :) There’s also a 6809 backend for gcc - https://gitlab.com/dfffffff/gcc6809 https://gitlab.com/dfffffff/gcc6809

zabzonk 5y ago
> My favourite 8 bit CPU! Mine too, on a Dragon 32. Such an elegant instruction set! I wrote about a half of a simulator for it in some years later in C++, but never got the whole thing working.

apricot 5y ago

I love the fact that it comes with a "CMOC for Basic Programmers" manual. http://perso.b2b2c.ca/~sarrazip/dev/cmoc-for-basic-programmers.html http://perso.b2b2c.ca/~sarrazip/dev/cmoc-for-basic-programme...

vaxman 5y ago
Because it also targets the CoCo (Tandy's Color Computer sold through the defunct Radio Shack retail chain). Yes, 6809 was an amazing microprocessor. It was doomed by the vaporware-ish Zilog Z8000 and the long delayed Motorola 68000 (the combined effect was to keep potential manufacturers of new 6809-based SBCs waiting on the sidelines for the new 16-bit generation microprocessors, while their much older 6502/8085/Z80/TMS9900 based boards skyrocketed in popularity...making it increasingly difficult to transition them to the far superior, but slightly software incompatible, 6809 microprocessors. Someone even had to eventually make a65C816 to keep the 6502 users on life support. The delayed 68000-series machines (which, like 6809, also broke software compatibility, but offered superior clock rates and 16-bit computing) came in too hot (the high-end workstations like Apple Lisa, SAGE, etc. followed by Mac, Amiga and Atari's knockoff of it.) This temporary market phenom also was probably the driving force behind Acorn/ARM, which is finally "taking over the game" (33 years later lol) after having been put on steroids by a few chip designers (first DEC with the StrongArm, now Apple with M1 Ultra, soon Ampere with the Siryn).

Annatar 5y ago

No full libc or float / double support - what's the point then?

glonq 5y ago
Yeah no SIMD either! /s
- Annatar 5y ago
  The MOS 6502 processor has only three 8-bit registers and only supports 8-bit integer arithmetic, so implementing one's own multiple precision floating point arithmetic is a major pain in the ass. If the C compiler doesn't provide the float and double data types, which are basic C datatypes, this means that a lot of modern software written in C cannot be compiled to 6502 machine code, and that one must write one's own arithmetic routines, at which point one is compelled to ask oneself: what's the benefit of the aforementioned C compiler when one would not be able to compile existing C software with it?