An MSX1: Z80 at 3.58 MHz, TMS9918 VDP, AY-3-8910 sound generator, 16 KB of VRAM and 8 KB of RAM. The cartridge brings 32 KB of ROM and carries neither a mapper nor RAM of its own.
At 32 KB the cartridge takes two pages of the memory map, from 0x4000 to 0xBFFF. The working RAM starts at 0xE000.
| range | what is there |
|---|---|
0x4000-0x4010 | the "AB" header and the entry point |
0x4010-0x4025 | a second "AB" header this cartridge never reads |
0x4025-0x4C19 | the skeleton: scenes, VDP, VRAM, sound, labels |
0x4C19-0x5645 | the presentation, the menu and the sound interpreter |
0x5645-0x651E | setting up the match, the frame, the clock and the goal |
0x651E-0x6BD8 | the penalty shoot-out |
0x6BD8-0x6D18 | the logo scene |
0x6D18-0x853E | the graphics and their loaders |
0x853E-0x8787 | the pitch map, compressed |
0x8787-0x9408 | the pieces, the ball physics and the aim |
0x9408-0xA219 | the pass, the shot, the goal lines and the restarts |
0xA219-0xB4C3 | the tactics and the intelligence |
0xB4C3-0xB9F9 | offside and the final screen |
0xB9F9-0xBFF3 | the trajectory and sprite tables |
0xBFF3-0xC000 | Konami's hidden mark |
The first four bytes say everything the BIOS needs:
41 42 70 40 "AB", and INIT at 0x4070The other three entries —STATEMENT, DEVICE and TEXT— are zero, and so are the six reserved bytes. This is a single-entry-point cartridge.
0x4070 hooks the interrupt at H.KEYI and settles into the jr $ at 0x40BE. The whole game hangs off the interrupt: there is no main loop.
At 0x4010 there is another "AB", with the 0x07 of RC-7xx and the 0x32 of RC-732 inside. Nothing here reads it. It is the header of the Konami Game Master, the cheat cartridge that plugs into the other slot and looks there for the addresses it may touch. Only four of Konami's cartridges carry it.
The eight VDP registers come from the table at 0x4889, and they are
02 E2 0E 7F 07 76 03 E4| register | value | what it sets |
|---|---|---|
| R0 | 0x02 | SCREEN 2 |
| R1 | 0xE2 | 16K, screen on, interrupt, 16x16 sprites |
| R2 | 0x0E | NAME table at 0x3800 |
| R3 | 0x7F | COLOUR table at 0x0000 |
| R4 | 0x07 | PATTERN table at 0x2000 |
| R5 | 0x76 | sprite ATTRIBUTES at 0x3B00 |
| R6 | 0x03 | sprite PATTERNS at 0x1800 |
| R7 | 0xE4 | border and backdrop |
R3 and R4 are not addresses: they are base and mask. Here they leave the COLOUR table low and the PATTERNS high, exactly the opposite of the usual layout. From that comes a rule that holds for all ten graphics batches: the colour of a pattern dump sits 0x2000 bytes lower, at the same address. The patterns at 0x2828 have their colour at 0x0828, the ones at 0x2998 at 0x0998, and so on.
R7 changes with the scene: 0xE4 at start-up and 0x00 during the match, so the pitch's backdrop is black, not blue.
An interpreter of its own at 0x4E50, with 54 sequences pointed at by the table at 0x50DA. The tones come from twelve bytes at 0x50CE, one per semitone, and the octave is got by shifting left.
The last thirteen bytes of the cartridge, from 0xBFF3 to 0xBFFF:
... 0A 32 AATen bytes with the title in katakana —コナミのサッカー— written backwards, its length (0x0A), the 0x32 of RC-732 and the closing 0xAA.
That this mark exists and what shape it has was discovered by Manuel Pazos, and this comes from him: all that was done here was checking that this cartridge carries it and that the number inside is its own.