The cartridge
16 KB in page 1 (0x4000-0x7FFF), an AB header with INIT at 0x407B and no BASIC. The screen is SCREEN 2.
The RAM
The game's whole RAM is 1 KB: 0xE000-0xE3FF, cleared by INIT with the ldir over itself. The stack sits at 0xE500.
| area | what is there |
|---|---|
0xE000 | the current scene |
0xE003 | the frame counter |
0xE005 | the interrupt re-entry lock |
0xE052 | the act type, 0 to 4 |
0xE0B0 | the buffer for the 32 sprites, copied whole to 0x3B00 every frame |
0xE130 | the player: position, position and pose |
0xE150 / 0xE170 / 0xE1B0 | the moving objects, the pick-ups and the loose one |
0xE280 | the second decompressor's buffer |
The BIOS
It uses seven routines: RDVDP, SETRD, SETWRT, WRTVDP, WRTPSG, RDPSG and SNSMAT. And it reads two bytes of its table, (0x0006) and (0x0007), which are the VDP ports.
The two menu screens
They are not the same one: the company screen (the KONAMI logo and "- VIDEO CARTRIDGE -") and the title screen. They share their scenery byte for byte; only the name table changes. Both are drawn from the ROM and checked down to zero bytes.
