Konami's Game Master 2

Konami's cheat cartridge from the inside: how it gets into 30 games, its SRAM, a two-player Tennis and Hockey, a biorhythm and nine tunes. 24 screens drawn from the ROM, on MSX and MSX2.

Konami - (c) Konami 1987 - An RC-755 cartridge, 128 KB with SRAM (Game Master 2 mapper) - MSX (and MSX2) - Dump 5c00f9e3...

Not one capture here. Every picture is drawn from the bytes of the ROM and checked to 0 bytes against the running cartridge or the openMSX VRAM. The tunes come from the cartridge's own engine and match openMSX frame by frame. The listing reassembles byte for byte with make.

The cartridge in numbers

100%of the binary explained
2,338named routines
40.1%of the listing commented
36,633bytes of code
94,439bytes of data
0bytes unidentified

What turned up when we took it apart

It also gets into MSX2 cartridges

To get into the game it looks in its start-up code for the address of an interrupt hook: first H.TIMI, where Konami's six MSX2 cartridges hook in, then H.KEYI, the MSX one (p00:588C). Game Master 1 only looked for the second.

Read in the code.

68 signatures for 30 games

If the game has no second header at 0x4010, it adds up the 256 bytes at 0x5000 and looks the sum up at p00:44BE: Game Master 1's 62 plus five for Vampire Killer and one for Hinotori. 35 are checked by adding up the ROMs.

On MSX it calls a routine that only exists on MSX2

To clear the VRAM it uses BIGFIL (0x016B) on MSX too, where that BIOS entry does not exist: the VRAM is not fully cleared. It does not show because what is left falls on characters the screen does not use.

Checked against openMSX.

Five tracks for three voices

The Tennis and Hockey engine has three music tracks and two effect tracks; the effects take PSG voice B or C while they play and give it back when they end (p08:A291). It never touches an SCC.

Checked against openMSX.

The biorhythm curves fade in

On MSX2 the colours of the three curves rise a little each day of the animation until they end up yellow, cyan and magenta (p06:A2B7).

Checked against openMSX.

A G inside the M

The “GAME MASTER II” title reuses characters between words (p09:8D99). At the bottom of the middle of the M of MASTER (p09:8DD5) it puts character 0x21, the corner of the G, where the M of GAME has 0x26.

Checked against openMSX.

What the cartridge draws

Under each picture is where it comes from and what is on it.

The main menu (p09:82CA).
The main menu (p09:82CA).
The same menu on a non-Japanese machine (p09:8D27).
The same menu on a non-Japanese machine (p09:8D27).
The menu of the cartridge on its own (p00:5DEE).
The menu of the cartridge on its own (p00:5DEE).
The tennis court ready to serve (p07:81A2).
The tennis court ready to serve (p07:81A2).
The hockey rink (p07:81A2).
The hockey rink (p07:81A2).
The biorhythm on MSX, with the example dates (p05:8B1B).
The biorhythm on MSX, with the example dates (p05:8B1B).
The title on MSX2 (p09:8B20).
The title on MSX2 (p09:8B20).
The menu on MSX2 (p09:8692).
The menu on MSX2 (p09:8692).
The biorhythm on MSX2 (p05:8B29).
The biorhythm on MSX2 (p05:8B29).