Fairlight: Routine at C000

Used by the routine at START.

Called once, from START, while the loading screen is still up: two voices on the beeper, a note at a time (TUNE_PLAY_NOTE), with the ROM's KEY-SCAN between notes. The voices' pointers are set from TUNE_VOICES first, so the tune starts from its beginning. The tune lasts 52.6 seconds (418 note bytes a voice, of which the last three rest in both and are passed over, so 415 notes heard, each 0.127 s; measured for the sounds page); after it both voices rest, and the routine goes on scanning the keyboard in silence.

Interrupts are off while it plays (KEY-SCAN does not need them); it turns them on as it returns, and START turns them off again three instructions later, for good.

From the first room on, these bytes are part of the clean copy of the screen (RESTOR copies the screen here), so the tune cannot be played again.

Used by the routine at START. Called once, from START, while the loading screen is still up: two voices on the beeper, a note at a time (TUNE_PLAY_NOTE), with the ROM's KEY-SCAN between notes. The voices' pointers are set from TUNE_VOICES first, so the tune starts from its beginning. The tune lasts 52.6 seconds (418 note bytes a voice, of which the last three rest in both and are passed over, so 415 notes heard, each 0.127 s; measured for the sounds page); after it both voices rest, and the routine goes on scanning the keyboard in silence. Interrupts are off while it plays (KEY-SCAN does not need them); it turns them on as it returns, and START turns them off again three instructions later, for good. From the first room on, these bytes are part of the clean copy of the screen (RESTOR copies the screen here), so the tune cannot be played again.
LOADING_TUNE	C000	LD HL,TUNE_VOICES	Both voices to the start of the tune: the four pointers from TUNE_VOICES.
	C003	LD DE,VOICE_ONE_AT
	C006	LD BC,$0008
	C009	LDIR
	C00B	DI	Interrupts off while it plays.
LOADING_TUNE_0	C00C	CALL TUNE_PLAY_NOTE	Play a note (once both voices are resting, nothing).
	C00F	CALL $028E	KEY-SCAN leaves E at $FF while no key is pressed.
	C012	LD A,$FF
	C014	CP E
	C015	JP Z,LOADING_TUNE_0
	C018	EI	A key.
	C019	RET	A key.