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.

 


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