Getting started

A commented disassembly of Cabbage Patch Kids (Konami, RC-716, 1984), the 16 KB MSX cartridge. Everything here comes out of the binary and can be generated from it again.

What you need

• Python 3 (no third-party packages)
• pasmo, to reassemble
• z80dasm, used only for the mnemonics
• the cartridge, which this repository does not distribute

It goes in the root as cabbagepatch.rom, 16,384 bytes, sha256

114945c770531db3ae61eb330d7ed870a3c00d3a90db2a29a4c134135c2c0707

and make comprueba checks it.

The test that decides

make verify

This reassembles src/cabbagepatch.asm with pasmo and compares the result, byte for byte, with the cartridge. If it says OK: reproducible byte a byte, the listing has invented nothing.

What reassembly cannot catch

A listing can reassemble perfectly and still be wrong: if drawings are read as instructions the bytes do not change, only what is said about them. So three more checks run alongside, all in make sanity:

• no range declared as data may come out as code (check_trace.py and check_datos_como_codigo.py, which crosses all 143 declared ranges against the trace);
• no entry point may fall inside one (check_entradas.py) — if both are declared at once, one of them is false;
• not one byte left unassigned (presupuesto.py). Today it says 16,384 of 16,384, 100%.

Everything you can run

make            # trace, listing, verify and the tests
make listado    # regenerates src/cabbagepatch.asm from the annotations
make sanity     # the checks reassembly does not cover
make densidad   # how much is commented, routine by routine
make imagenes   # redraws the PNGs in docs/imagenes from the ROM
make web        # regenerates this site
make test       # the tests

And one more that is specific to this cartridge:

python3 tools/repasa_el_porte.py

The annotations were ported from another cartridge — see Findings — and that tool is the guardian for it: it checks that no address cited in a comment is a leftover, that the other game is not named where it should not be, and it lists every comment that is identical to the sibling's but sits on a different instruction.

What is in here

• src/cabbagepatch.asm — the listing; generated, not hand-edited
• src/cabbagepatch.notes — the annotations, anchored to addresses
• src/cabbagepatch.entries — the entry points, each one justified
• src/cabbagepatch.nocode — the dispatch tables, which the tracer must not read as code
• docs/ — this site, in English and Spanish
• tools/ — the tracer, the listing generator, the format walkers and the drawing tools