Set Real Mode Interrupt Vector

Call With

AX = 0201H
BL = interrupt number
CX:DX = segment:offset of real mode interrupt handler

Returns

Carry flag = clear (this function always succeeds)

Notes

• 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.