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History of SixtyPical


  • Add word (constant or memory location) to word memory location.
  • Add word to pointer (unchecked for now).
  • Added word table type.
  • Can copy from word storage location to word table and back.
  • A vector can name itself in its inputs and outputs or trashes sets.
  • Implementation: --debug shows some extra info during analysis.
  • Fixed bug where copying literal word into word storage used wrong endianness.
  • Fixed bug where every memory location was allocated 2 bytes of storage, regardless of type.
  • Tests: use to disassemble code for comparison.


  • Explicit word literals prefixed with word token.
  • Can copy literals into user-defined destinations.
  • Fixed bug where loop variable wasn't being checked at end of repeat loop.
  • buffer and pointer types.
  • copy ^ syntax to load the addr of a buffer into a pointer.
  • copy []+y syntax to read and write values to and from memory through a pointer.


  • User-defined byte locations can be given an initial value.
  • word type locations which can be defined and copyed between.
  • Can copy directly from one user-defined byte location to another.


  • Added routine and vector types, and copy instruction.
  • Both routines and vectors can declare inputs, outputs, and trashes, and these must be compatible to assign a routine or vector to a vector.
  • Added goto (tail call) instruction, jumps to routine or through vector.
  • call can call a subroutine indirectly, via a vector.
  • Routine name is now shown in analysis error messages.


  • Added byte table type locations and indexed addressing (+ x, + y).
  • Integer literals may be given in hexadecimal.
  • Line comments may be included in source code by prefixing them with //.


  • Added repeat loops to the language, which can repeat until a flag is set (or not set), or which can repeat forever.
  • if not inverts the sense of the test.
  • Added explicitly-addressed memory locations.


  • Added external routine declarations.
  • Added ability to compile to 6502 machine code and output a PRG file.


A complete reboot of SixtyPical 0.1. The reference implementation was rewritten in Python. The language was much simplified. The aim was to get the analysis completely right before adding more sophisticated and useful features in future versions.


Initial inspired-but-messy version implemented in Haskell.