DOS/32 Advanced DOS Extender - Documentation: Programmer's Reference []

DOS/32 Advanced DOS Extender - Programmer's Reference

2.18 - DPMI function 0201h - Set Real Mode Interrupt Vector

Sets the current virtual machine's real mode interrupt vector for the specified interrupt.

In:	AX = 0201h BL = interrupt number CX:DX = segment:offset of real mode interrupt handler
Out:	CF clear

Notes:

a) 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 (ie below the 1 MB boundary) or the client must allocate a real mode callback address. See DPMI functions 0100h and 0303h.

b) If the interrupt being hooked is a hardware interrupt, the memory that the interrupt handler uses should be locked.

c) DOS/32 Advanced DPMI will temporarily disable the Null-Pointer Protection (if it was enabled) in order to modify the first four interrupt vectors, INTs 00-03h.