Getting started

Just reading

The listings in src/*.asm are commented and need nothing built to be read. Where to start, depending on what you're after:

I want to see...	look at
How the game boots	`alehop_game_nucleo.asm`, at 0xC000
The engine: physics, collision, scrolling	`alehop_game_extra.asm`
The music player	`alehop_game_sonido.asm`
The turbo tape loader	`alehop_slots.asm`
The maps and graphics	`alehop_game_datos.asm`

The comments are in Spanish, matching the game's own language.

Rebuilding it

make

That extracts the tape, traces the code, regenerates the five game listings plus the other three modules, and verifies everything. Green means four things:

Every listing reassembles to the original binary, byte for byte.
The five game chunks, concatenated in load order, reproduce the whole turbo block.
No data region has been mistaken for code.
Not one byte of the 42645 is unexplained.

Then the 36 tests run.

You'll need:

python3
pasmo — to assemble (brew install pasmo)
z80dasm — to disassemble
openmsx — only for the emulator parts

**The .tsx tape image isn't distributed** with this repository. Without it, make says what it can't do rather than pretending it went fine.

The images

make imagenes

Draws the six levels from the game's own data: the full strip for each one (2048x64) and a real screen with its three bands. These aren't screen captures — they're generated by decompressing the graphics and assembling the maps, which is the best evidence that the format is properly understood.

The emulator

ALEHOP_TSX="$PWD/alehop.tsx" ALEHOP_OUT="$PWD/dump" \
  openmsx -machine Philips_VG_8020-20 -script tools/omsx_load.tcl

This loads the original tape using the game's own loader as the decoder and dumps RAM at each stage. It produces dump/full_recolocado.bin, the 64 KB image the code is traced against: addresses only mean anything once the game has been relocated in memory.

To watch it play and take screenshots:

ALEHOP_TSX="$PWD/build/alehop_rebuild.tsx" ALEHOP_OUT="$PWD/build/capturas" \
  openmsx -machine Philips_VG_8020-20 -script tools/omsx_juega.tcl

Loading takes about seven minutes of emulated time, same as it did in 1988.

Modifying the game

Start in src/*.notes: that's where the comments live, anchored to addresses so they survive a full re-trace. The .asm files are generated, so don't edit them by hand.

To change the code, edit the relevant .asm and then:

python3 tools/build_tape.py build build/my_alehop.tsx

That assembles, rebuilds the blocks with their headers and checksums, and produces a loadable tape. As long as make was green before you touched anything, any change in behaviour can be pinned on what you changed rather than on a misreading of the binary.