Note: This API call is for DOS personality only. Use Family API for portability.
Int 21H, AH=51H
2 and higher
GET CURRENT PROCESS ID (GET PSP ADDRESS)
AH = 51h
BX = segment of PSP for current process
DOS uses the current PSP address to determine which processes own files and memory; it corresponds to process identifiers used by other OSs under DOS 2.x, this function cannot be invoked inside an INT 28h handler without setting the Critical Error flag under DOS 3.0+, this function does not use any of the DOS-internal stacks and may thus be called at any time, even during another INT 21h call supported by OS/2 compatibility box identical to the documented AH=62h this call was undocumented prior to the release of DOS 5.0
Text based on Ralf Brown Interrupt List Release 61