CD-ROM BIOS Functions (8)
Last Update:  14 April 1997

Label:  CD_BOOT		Addr:  $E000
function:  Boot the CD-ROM BIOS
IN:  N/A
OUT: N/A

Brings you to the familiar CD-ROM startup screen.


Label:  CD_FADE		Addr:  $E02D
function:  Begin or cancel linear PCM or ADPCM fade out
IN:  reg A = mode
	$00:  Cancel fade out
	$08:  PCM fade out (6.0 secs)
	$0A:  ADPCM fade out (6.0 secs)
	$0C:  PCM fade out (2.5 secs)
	$0E:  ADPCM fade out (2.5 secs)
OUT:  N/A


Label:  AD_RESET	Addr:  $E030
function:  Reset the ADPCM controller
IN:  N/A
OUT: N/A


Label:  AD_READ		Addr:  $E036
function:  Read data from ADPCM to memory
IN:  	_CX:  ADPCM buffer address
     	_DH:  Destination data address type
	      $00:  Local	$FF:  VRAM	$02-$06: MPR #
     	_BL:  addr low bits	low bits	Bank # ($80-$87)
	_BH:  addr high bits	high bits	Not Used
	_AX:  data size to be read (in bytes)

OUT:  reg A = error status
     	$00:  operation success
	other: error


Notes:  When reading into VRAM, $2272 (VDTIN_FLG) becomes 1.


Label:  AD_WRITE	Addr:  $E039
function:  Write to ADPCM buffer from memory
IN:	_CX:  ADPCM buffer address
	_DH:  Source data address type
	      $00:  Local	$FF:  VRAM	$02-$06:  MPR #	
	_BL:  addr low bits	low bits	Bank # ($80-$87)
	_BH:  addr high bits	high bits	Not Used
	_AX:  data size in bytes

OUT:  reg A = error status
	$00:  no error
	other: error

Notes:  When reading from VRAM, $2272 (VDTIN_FLG) becomes 1.


Label:  AD_PLAY		Addr:  $E03C
function:  Playback a section of data from ADPCM buffer
IN:	_BX:  ADPCM buffer playback start address (START)
	_AX:  Size of data to playback in bytes (LENGTH)
	_DH:  Sampling rate (range:  $00-$0E) (RATE)
	      Khz = 32 / (16 - _DH)
	_DL:  Mode
	      bit 0:  Counter Mode
		      0:  Set START, LENGTH, and RATE
		      1:  Playback using previous START, LENGTH, and RATE
	      bit 7:  Play Mode
		      0:  Auto Stop
		      1:  Repeat


OUT:	reg A = error status
	$00:  no error
	other: error

Notes:  An error will occur if AD_PLAY is called during playback of ADPCM.
	Before executing, call AD_STOP to halt the current playback followed
	by AD_STAT to confirm that playback has stopped.


Label:  AD_STOP		Addr:  $E042
function:  Stop playback of ADPCM buffer data
IN:	N/A
OUT:	N/A


Label:  AD_STAT		Addr:  $E045
function:  Read the state of the ADPCM controller
IN:	N/A
OUT:	reg A:  State of ADPCM controller
		$00:  ADPCM not busy (end or not playing)
		other:  ADPCM busy

	reg X:	ADPCM buffer and playback state
		$00:  Playback in progress and more than half
		      of the buffer data is remaining.
		$01:  Playback halted
		$04:  Playback in progrss and less than half
		      of the buffer data is remaining.