“… SPL/M is a “small” subset of PL/M, the very first high-level language written specifically for an 8-bit microprocessor (in that case, the Intel 8008) by Dr. Gary Kildall: author of CP/M (written in PL/M!), founder of Digital Research, Inc., educator, TV host, and bon vivant. In 1977, Tom Crosley created a subset of PL/M for his 20KB RAM, 6800-based computer and made a presentation about it at the 2nd West Coast Computer Faire in 1978. The rest is history…or is it??? Crosley himself confirmed just this year that versions of SPL/M existed for the Apple II, IBM PC, and other small machines, but the code is lost…so far!”
I wrote industrial code in PL/M (for an 8085 target) between 1980 and 1983. PL/M had loops and if statements and variables. It was fine. See Now It Can Be Told.
A few years ago, I was thinking of reviving PL/M for the Web Assembly platform (WASM), in order to take advantage of direct allocations… There’s still an argument to be made for this peculiar combination of high-level and very low-level elements.
I did look at it when I started my 6502 project some time back (eek, 8 years now!) - no compilers for the 6502 (that I could find) and I felt it shouldn’t be that hard, however one of many things I never got round to …
The 6502 like the the PDP-8 may be just too primitive to have a compiled
native language. Vitrual machines how ever work great. The lack of stack
addressing is the other limiting factor on the 6502,6800, and 8080/Z80.
There are many compilers for many languages for the 6502. At least 4 C compilers that I know about which work well to compile (or compile and assemble) to native 6502 machine code (cc65, vbc, calypsi, llvm-mos).
I used the Aztec C compiler in the early 80s on the Apple II so it’s not a new concept.
I think you’ll find similar in the 8080/Z80 world too. Let’s not forget the language this very thread is all about; PL/M which was used to compile parts of CP/M which ran on the 8080 and Z80…
There is even a working C compiler for the PDP-8. (although somewhat cut-down PDP-8 C Compiler )
I think, PL/M just doesn’t make sense for the 6502. The low-level features, like register types, are really about fine tuning tasks and avoiding memory access, which is fine and sensible, if you have a handful or so of registers to juggle with. With just the accumulator and two auxiliary index registers, like on the 65xx family, there isn’t much that an optimized compiler couldn’t do as well.
I remember using something called PL/9 on FLEX-09 on my 6809 homebrew machine. It was high level enough to be C like - a single pass compiler/editor for the 6809. I wrote a floppy disk formatter with it.
See