The code

The numbers

• 100% of the binary explained: 35,620 bytes of traced code and 95,452 of named data, which add up to the cartridge's 131,072.
• 17,071 instructions in banks 0, 1, 2, 3, 4, 6, 9, 12 and 15, with 7,985 comments: 46.8%.
• 2,190 routines and labels; none below 10% of comments, and no call to an unnamed routine.

How it is organised

The frame's game (p01:6672) dispatches on the game state (0xC000): the logo and the title, the wait, the demo, PLAY START, the new game, the game, GAME OVER, the pause and the ending.

Inside the game (p01:6F18) the mode rules (0xC151, table p01:6F7A): play, room change, the weapons and equipment windows, the transceiver, the lorry, the lift, opening a door, the telescope, Snake dead, the text window, the capture and room 0x85.

Snake has his own state (0xC180, table p01:6001) and his pose mode (0xC18B, table p01:6508).

The records

IX points to three kinds of record, and tools/anotaciones.py comments their fields wherever IX is surely one of them:

• actor (0xD000, 16 of 0x80): +0 the type (bit 7: dying), +1 the step, +3 the Y, +5 the X, +7/+9 the speeds, +0x0B the frame, +0x0C the frame count, +0x0D the stamina, +0x0E what it collides with, +0x11 the direction, +0x1E the hit marks, +0x20 how many sprites;
• projectile (0xC200, 6 of 0x40): the weapon, the step, the Y, the X, the ground Y and whether it hurts;
• sound channel (0xC010, 4 of 0x20): the list, the note, the period, the volume, the instrument and the vibrato.

Actors

Each type has two handlers: creation (p00:575F, table p00:5762) and every frame (p01:722C, table p01:722F, from the loop at p01:71E5). In the listing they are called crea_tipo_N and cuadro_tipo_N. The frame's collisions are at p02:88EF: projectiles against actors, Snake against actors, the tiles and rooms that hurt, doors and items.

Texts

159 texts (p12:A37D) with 92 shared pieces (p12:B8A7): a byte from 0xA1 on inserts a piece. The window works in steps (p00:5D03) and writes a letter every 4 frames with its sound.

The names

The names and the automatic comments come from tools/anotaciones.py, each with the routine where it is read; tools/anota.py writes them into the notes. The per-type handlers are named on their own from the two dispatch tables, and the bank 0 trampolines after the routine they call.