USER subroutine

The USER subroutine (not called, always jumped to by the BIOS) needs to perform actions according to the command value set in USER_REQUEST ($l0FDAE.b).

Command 0

Initilization of the soft/debug DIPs in the 68k user RAM. Used only once, when the game is started for the first time on a MVS system (probably when the BIOS doesn't find the game's NGH number in the backup RAM).

(The DIPs settings in RAM should then be copied to backup RAM by calling what function ?)

Initilization of the rest of the user RAM, the display, and I/O.

Command 1

Show the game's own boot logo animation (when $114 = 1).

Command 2

Show demo. Jump to SYSTEM_RETURN when finished.

Command 3

Show title. SELECT_TIMER ($10FDDA.b) is used as a count-down timer.