Getting started

This repository holds the commented disassembly of Konami's The Goonies for the MSX (RC-734, 1986). It does not hold the cartridge: the ROM image is not distributed.

What you need

• pasmo — the assembler that reproduces the ROM
• z80dasm — the disassembler the listing is generated with
• python3 — the tools under tools/
• make
• Your own copy of the cartridge, in the root and named goonies.rom

It is exactly 32,768 bytes and its fingerprint is:

sha256  2ba602b1a17e4797da1588afe6e65640331c15746bf5959f4778b404be929dde

To check it:

make comprueba

Reproducing the whole thing

make

That chains the four things that matter:

step	what it does	what it proves
make listado	builds src/goonies.asm from the trace and the notes	that the listing is not hand-written
make verify	reassembles and compares the sha256	that the listing is the cartridge
make sanity	checks how the bytes are accounted for	that not one byte is left unexplained
make test	44 checks	that what gets published holds up against the bytes

The one that decides is make verify. If the reassembled sha256 is not the one above, the listing is lying somewhere.

The numbers

make densidad

0 routines below 10 %, out of 1176
in total: 8774 instructions, 3236 comments, 36.9 %

The pictures

make imagenes

Draws into work/gfx/ the title screen, the twenty-five level maps with their creatures and hazards, the five round minimaps, the player's figures in colour, the tile sheet and the twenty-three inventory icons. None of them is a capture: they are built by running in Python the same steps the Z80 runs.

Checking against the emulator

make vram

Boots openMSX with the cartridge, lets it run from cold and dumps VRAM at five instants; then it subtracts that VRAM from the one tools/vram.py builds. No playing and nothing to load: the intro, the title and the demo come up on their own and are deterministic, because the demo is a recorded game.

Latest measurement, on the latest build:

screen           colour       spr patt     patterns     names
title            0/6144       0/2048       0/6144       0/768
the nine         0/6144       0/2048       0/6144
level 1 room 1   0/6144       0/2048       0/6144
level 1 room 2   0/6144       0/2048       0/6144
level 1 room 3   0/6144       0/2048       0/6144

How the commenting works

Batches of comments are written into work/coment/tanda-NN-whatever.notes, with lines C 0xADDR text, L 0xADDR name and B 0xADDR HEADING, and then:

python3 tools/aplica_comentarios.py src/goonies.asm src/goonies.notes \
        work/coment --escribe && make listado && make verify

There are forty-two batches.