git @ Cat's Eye Technologies SixtyPical / 0.6

Tree @0.6 (Download .tar.gz)


SixtyPical is a very low-level programming language, similar to 6502 assembly, with static analysis through abstract interpretation.

In practice, this means it catches things like

  • you forgot to clear carry before adding something to the accumulator
  • a subroutine that you call trashes a register you thought was preserved
  • you tried to write the address of something that was not a routine, to a jump vector

and suchlike. It also provides some convenient operations and abstractions based on common machine-language programming idioms, such as

  • copying values from one register to another (via a third register when there are no underlying instructions that directly support it)
  • explicit tail calls
  • indirect subroutine calls

The reference implementation can execute, analyze, and compile SixtyPical programs to 6502 machine code.

It is a work in progress, currently at the proof-of-concept stage.

The current released version of SixtyPical is 0.6. The current development version of SixtyPical, unreleased as of this writing, is 0.7-PRE.



For 0.7:

  • always analyze before executing or compiling, unless told not to
  • word type.
  • word table type.

For 0.8:

  • zero-page memory locations.
  • indirect addressing.

At some point...

  • trash instruction.
  • interrupt routines.
  • 6502-mnemonic aliases (sec, clc)
  • other handy aliases (eq for z, etc.)
  • have copy instruction able to copy a constant to a user-def mem loc, etc.
  • add absolute addressing in shl/shr, absolute-indexed for add, sub, etc.
  • check and disallow recursion.