WonderWitch/FreyaBIOS/Bank

The Bank interrupt provides an abstraction layer for accessing the WonderWitch cartridge's flash and RAM.

Interrupts

INT $18/AH=$00 - bank_set_map

• AH = $00
• BL = Bank region
• CX = Number of bank to map to region

Bank regions:

• 0 = SRAM (1000:xxxx)
• 1 = ROM0 (2000:xxxx)
• 2 = ROM1 (3000:xxxx)

INT $18/AH=$01 - bank_get_map

• AH = $01
• BL = Bank region

Return:

• AX = Number of bank mapped to region

INT $18/AH=$02 - bank_read_byte

• AH = $02
• BX = Bank ID
• DX = Offset within bank

Return:

• AL = Byte read

Bank ID format:

15  bit  8  7  bit  0
 ---- ----  ---- ----
 tiii iiii  iiii iiii
 |||| ||||  |||| ||||
 |+++-++++--++++-++++- Number of bank
 +-------------------- 0 = SRAM, 1 = Flash

INT $18/AH=$03 - bank_write_byte

• AH = $03
• BX = Bank ID
• CL = Byte to write
• DX = Offset within bank

INT $18/AH=$04 - bank_read_word

• AH = $04
• BX = Bank ID
• DX = Offset within bank

Return:

• AX = Word read

INT $18/AH=$05 - bank_write_word

• AH = $05
• BX = Bank ID
• CX = Word to write
• DX = Offset within bank

INT $18/AH=$06 - bank_read_block

• AH = $06
• BX = Bank ID
• CX = Number of bytes to read
• DX = Offset within bank
• DS:SI = Output buffer, of size CX

INT $18/AH=$07 - bank_write_block

• AH = $07
• BX = Bank ID
• CX = Number of bytes to write
• DX = Offset within bank
• DS:SI = Input buffer, of size CX

Return:

• AX = zero on success (undocumented)

INT $18/AH=$08 - bank_fill_block

• AH = $08
• AL = Fill value
• BX = Bank ID
• CX = Number of bytes to write
• DX = Offset within bank

Sets CX bytes in bank BX to value AL starting at offset DX.

INT $18/AH=$09 - bank_erase_flash

• AH = $09
• BX = Bank ID

Return:

• AX = zero on success (undocumented)