Int 31H Function 0800H

Physical Address Mapping [0.9]

Converts a physical address into a linear address. This function allows device drivers running under DPMI hosts which use paging to reach physical memory that is associated with their devices above the 1 MB boundary Examples of such devices are the Weitek numeric coprocessor (usually mapped at 3 GB), buffers that hold scanner bit maps, and high-end displays that can be configured to make display memory appear in extended memory.

Call With

AX = 0800H
BX:CX = physical address of memory
SI:DI = size of region to map (bytes)


if function successful
Carry flag = clear
BX:CX = linear address that can be used to access the physical memory
if function unsuccessful
Carry flag = set
AX = error code
8003Hsystem integrity (DPMI host memory region)
8021Hinvalid value (address is below 1 MB boundary)


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