Atic Atac: Routine at 807A

The handler for everything that is drawn but never acts -- the three control-method pictures on the title screen among them. It checks whether IX is one of the first three monster records and, if it is, burns a couple of hundred cycles doing nothing; otherwise it returns at once.

The delay looks pointless but is not: those three slots are drawn every frame whatever occupies them, and an inert occupant that returned instantly would make the frame shorter than one holding a creature. Spending the time keeps the pace even.

The handler for everything that is drawn but never acts -- the three control-method pictures on the title screen among them. It checks whether IX is one of the first three monster records and, if it is, burns a couple of hundred cycles doing nothing; otherwise it returns at once. The delay looks pointless but is not: those three slots are drawn every frame whatever occupies them, and an inert occupant that returned instantly would make the frame shorter than one holding a creature. Spending the time keeps the pace even.
INERT_SPRITE	807A	PUSH IX	IX, as a number, against the base of the monster table.
	807C	POP HL
	807D	LD DE,$EE60
	8080	AND A	Not in the table at all -- nothing to do.
	8081	SBC HL,DE
	8083	LD A,H
	8084	AND A
	8085	RET NZ
	8086	LD A,L	Only the first three slots get the delay.
	8087	CP $30
	8089	RET NC
	808A	LD HL,$00C0	192, counted down and thrown away.
INERT_SPRITE_0	808D	DEC HL	The delay itself.
	808E	LD A,H
	808F	OR L
	8090	JR NZ,INERT_SPRITE_0
	8092	RET