Skool Daze: Routine at $BA48

$BA48: Play the 'Got all shields' tune

Used by the routine at $2BB0.
$BA48	SEI	Disable interrupts.
$BA49	LDA #$BA	Set the interrupt routine address at $FFFE to $BAB4.
$BA4B	STA $FFFF
$BA4E	LDA #$B4
$BA50	STA $FFFE
$BA53	JSR $BA90	Initialise the tune buffer.
$BA56	LDA #$73	The 'Got all shields' tune data for voice #1 is at $BC73.
$BA58	STA $BBC3
$BA5B	LDA #$BC
$BA5D	STA $BBC6
$BA60	LDA #$A0	The 'Got all shields' tune data for voice #2 is at $BCA0.
$BA62	STA $BBC4
$BA65	LDA #$BC
$BA67	STA $BBC7
$BA6A	LDA #$C7	The 'Got all shields' tune data for voice #3 is at $BCC7.
$BA6C	STA $BBC5
$BA6F	LDA #$BC
$BA71	STA $BBC8
$BA74	JSR $B9A0	Initialise voices #1, #2 and #3.
$BA77	CLI	Re-enable interrupts to start playing the tune.
$BA78	LDA $BBCE	Has the tune finished playing yet?
$BA7B	BNE $BA80	Branch if so.
$BA7D	JMP $BA78	Otherwise check again.
$BA80	SEI	Disable interrupts.
$BA81	LDA #$39	Set the interrupt routine address at $FFFE back to $39C7.
$BA83	STA $FFFF
$BA86	LDA #$C7
$BA88	STA $FFFE
$BA8B	CLI	Re-enable interrupts.
$BA8C	JSR $302A	Initialise voice #3.
$BA8F	RTS