Int 31H Function 0201H
Set Real Mode Interrupt Vector
Sets the current virtual machine's real mode interrupt
vector for the specified interrupt.
AX = 0201H
BL = interrupt number
CX:DX = segment:offset of real mode interrupt handler
Carry flag = clear (this function always succeeds)
- The address passed in CX must be a real mode segment address, not
a selector. Consequently, the interrupt handler must either reside in
DOS memory (i.e. below the 1 MB boundary) or the client must allocate
a real mode callback address. See Int 31H
Functions 0100H and 0303H.
- If the interrupt being hooked is a hardware interrupt, the memory
that the interrupt handler uses must be locked.