BIOS calls

Please see ASM Defines or C Defines for the hex addresses.

Simplify hierarchy and tell on which system each call works ?

Universal BIOS calls

BIOS calls common to every system.

BIOSF_? ($C0044A): (Called every frame)

Sets values in RAM according to buttons states. Often called each frame.

Memory locations set:

BIOS_P1CURRENT     $10FD95 Joystick 1 state
BIOS_P1PREVIOUS    $10FD96 Previous joystick 1 state
BIOS_P1CHANGE      $10FD97 Joystick 1 state change (edges)
BIOS_P1REPEAT      $10FD98 Joystick 1 repeat (edge, and strobe if held more than ? calls)

BIOS_P2CURRENT     $10FD9B Joystick 2 state
BIOS_P2PREVIOUS    $10FD9C Previous joystick 2 state
BIOS_P2CHANGE      $10FD9D Joystick 2 state change (edges)
BIOS_P2REPEAT      $10FD9E Joystick 2 repeat (edge, and strobe if held more than ? calls)

BIOS_STATCURNT     Joystick 1/2 start/select state
BIOS_STATCHANGE    Previous Joystick 1/2 start/select state

Bit definitions: see Joypads

AES/MVS BIOS calls

AES/MVS specific calls.

BIOSF_CRDACCESS: Perform memory card operation

(Informations provided by User:Smkdan)

Memory locations used (all 8bit):

BIOS_CRDF       (8bit): function to perform when calling BIOSF_CRDACCESS, see below table
BIOS_CRDRESULT  (8bit): 00 on success, else 80+ and encodes the error, see below table
BIOS_CRDPTR     (32bit): pointer to read from/write to
BIOS_CRDSIZE    (16bit): how much data to read/write from/to card
BIOS_CRDNGH     (16bit): usually game NGH.  Unique identifier for the game that 'owns' the save file
BIOS_CRDFILE    (16bit): each NGH has up to 16 save 'files' associated with

To access memory card, the RAM addresses above must be set depending on the function being attempted BIOS_CRDF values:

$00 (Format)

No extra parameters

$01 (Find)

In: BIOS_CRDNGH: NGH to find save files for

Out: BIOS_CRDFILE: 16bit mask containing 1 bits for each one of the 16 save files if present.

0 bits mean the save file is not present. i.e. FFFF = all 16 saves used, 8000 = only save file 15 is used

$02 (Load)

In:

CRDPTR: pointer to store loaded data to

CRDSIZE: the max size of data to load (automatically stops when entire file is loaded)

CRDNGH: NGH of file

CRDFILE: the file # of the given NGH to load from

$03 (Save)

In:

CRDPTR: pointer to read data to store to the card

CRDSIZE: size of data to save

CRDNGH: NGH of file

CRDFILE: the file # of the given NGH to save as

$04 (Delete)

In:

CRDNGH: NGH of file

CRDFILE: the file # of the given NGH to delete

$05 (GETNAME)

Gets name of a save file, forgot how these work...

$06 (SETUSER) (the username of the card)

$07 (GETUSER)

Errors may occur and the BIOS will store a value in BIOS_CRDRESULT depending on what went wrong:

• $00: no errors
• $80: no card inserted
• $81: card inserted, but not formatted
• $82: attempted to load a file that doesn't exist on the card
• $83: checksum error?
• $84: attempted to save to a full card
• $85: card write protect switch is active

CD BIOS calls

• Same ones as the AES/MVS ?

BIOSF_UPLOAD ($C00546): Upload data to DRAM

Arguments:

• $10FEF8: Source (Long)
• $10FEF4: Destination (Long)
• $10FEDA: Zone (Byte, 0=PRG, 1=FIX, 2=SPR, 3=Z80, 4=PCM, 5=PAT)
• $10FEFC: Size (Long)
• $10FEDB: Bank (Byte)

For FIX, Z80 (, PAT ?) and PCM upload, Destination has to be multiplied by 2 (8 bit busses). SPR bank size is 1MiB (4 banks), PCM bank size is 512KiB (4 banks).

$10FEF4 is auto-incremented by the size upon completion, which allows to do multiple consecutive uploads.

BIOSF_LOADFILE ($C00552): Load file from CD (with animation)

A0 points to a file information block made of:

• File name, ends with 0 (32 chars buffer ?)
• Bank (byte)
• Eventual padding bytes to align Offset
• Offset (long)

For FIX, Z80 and PCM files, Offset is multiplied by 2 (8 bit busses).

The destination memory is automatically chosen according to the file's extension.

BIOSF_CDDACMD ($C0056A): Issue CDDA command

Word in D0, command/track ?

CDZ BIOS calls

• Check track 0 ? Copy protection