WonderWitch/FreyaBIOS/System

The System interrupt provides assorted system-related functionality.

Types

Suspend/resume structure

This structure is stored in SRAM block 3, offset $7E00 (core 1) and $BF00 (core 0).

Offset	Size	Contents
$0000	16384	Copy of RAM area $0000 - $3FFF
$4000	2	Stack segment?
$4002	2	Data segment?
$4004	224	Copy of IO ports $00 - $DF
$40E4	6	?

Interrupts

INT $17/AH=$00 - sys_interrupt_set_hook

• AH = $00
• AL = Interrupt index
• DS:BX = Pointer to new vector (read from)
• DS:DX = Pointer to old vector (written to)

INT $17/AH=$01 - sys_interrupt_reset_hook

• AH = $01
• AL = Interrupt index
• DS:BX = Pointer to old vector (read from)

INT $17/AH=$02 - sys_wait

• AH = $02
• CX = Frames to wait

INT $17/AH=$03 - sys_get_tick_count

• AH = $03

Return:

• DX:AX = Number of frames since system start

INT $17/AH=$0A - sys_get_ownerinfo

• AH = $0A
• DS:DX = Output buffer
• CX = Output buffer size, in bytes

Errata:

• The FreyaBIOS implementation only works correctly in the "mono" mode. An alternate implementation that supports "color" mode is provided as part of libwwc.

INT $17/AH=$12 - sys_get_version

• AH = $12

Return:

• AX = BIOS version