millfork/doc/api/target-platforms.md

Target platforms

Currently, Millfork supports creating disk- or tape-based programs for Commodore, Apple and Atari 8-bit computers, but it may be expanded to support other 6502-based platforms in the future.

Supported platforms

The following platforms are currently supported:

• c64 – Commodore 64

• c64_scpu – Commodore 64 with SuperCPU in emulation mode

• c64_scpu16 – Commodore 64 with SuperCPU in native, 16-bit mode (very buggy)

• c16 – Commodore 16

• plus4 – Commodore Plus/4

• vic20 – Commodore VIC-20 without memory expansion

• vic20_3k – Commodore VIC-20 with 3K memory expansion

• vic20_8k – Commodore VIC-20 with 8K or 16K memory expansion

• c128 – Commodore 128 in its native mode

• pet – Commodore PET

• a8 – Atari 8-bit computers

• apple2 – Apple II+/IIe/Enhanced IIe

The primary and most tested platform is Commodore 64.

Currently, all targets assume that the program will be loaded from disk or tape. Cartridge targets are not yet available.

A note about Apple II

Apple II variants other than II+/IIe/Enhanced IIe are untested; this includes the original II, IIc and IIc+, but also later compatible computers (Apple III and IIgs). They may or may not work.

The compiler output is a raw machine code file, which then has to be put on a disk. You can do it using CiderPress, AppleCommander, or some other tool.

The file has to be loaded from $0C00. An example how to put such file onto a disk using AppleCommander:

java -jar AppleCommander-1.3.5.jar -p disk_image.dsk FILENAME B 0xc00 < compiler_output.a2

Creating a bootable disk is beyond the scope of this document.

Adding a custom platform

Every platform is defined in an .ini file with an appropriate name.

[compilation] section

• arch – CPU architecture. It defines which instructions are available. Available values:

  • nmos (original 6502)

  • strict (NMOS without illegal instructions)

  • ricoh (Ricoh 2A03/2A07, NMOS without decimal mode)

  • strictricoh (Ricoh 2A03/2A07 without illegal instructions)

  • cmos (WDC 65C02 or 65SC02)

  • 65ce02 (CSG 65CE02; experimental)

  • huc6280 (Hudson HuC6280; experimental)

  • 65816 (WDC 65816/65802; experimental; currently only programs that use only 16-bit addressing are supported)

• modules – comma-separated list of modules that will be automatically imported

• other compilation options (they can be overridden using commandline options):

  • emit_illegals – whether the compiler should emit illegal instructions, default false

  • emit_cmos – whether the compiler should emit CMOS instructions, default is true on compatible processors and false elsewhere

  • emit_65816 – which 65816 instructions should the compiler emit, either no, emulation or native

  • decimal_mode – whether the compiler should emit decimal instructions, default is false on ricoh and strictricoh and true elsewhere

  • ro_arrays – whether the compiler should warn upon array writes, default is false

  • prevent_jmp_indirect_bug – whether the compiler should try to avoid the indirect JMP bug, default is false on 65C02-compatible processors and true elsewhere

[allocation] section

• main_org – the address for the main function; all the other functions will be placed after it

• zp_pointers – either a list of comma separated zeropage addresses that can be used by the program as zeropage pointers, or all for all. Each value should be the address of the first of two free bytes in the zeropage.

• himem_style – not yet supported

• himem_start – the first address used for non-zeropage variables, or after_code if the variables should be allocated after the code

• himem_end – the last address available for non-zeropage variables

[output] section

• style – not yet supported

• format – output file format; a comma-separated list of tokens:

  • literal byte values

  • startaddr – little-endian 16-bit address of the first used byte of the compiled output

  • endaddr – little-endian 16-bit address of the last used byte of the compiled output

  • allocated – all used bytes

  • <addr>:<addr> - inclusive range of bytes

• extension – target file extension, with or without the dot