INT 21,51 - Get Current Process ID (Undocumented DOS 2.x)

AH = 51h

on return:

BX = process ID

- The process ID number is actually the segment address of program's

PSP. This in conjunction with ~INT 21,50~ is useful for TSR's to

access their own file handle table in their respective ~PSP~.

- this function cannot be called while in an ~INT 28~ handler in

DOS 2.x unless the critical error flag is set or stack corruption

will occur

- ~INT 21,62~ is highly recommended for DOS 3.x due to a possible bug

when activated from a TSR. DOS may switch to the wrong internal

stack which may cause a problems with TSR's if called during an

INT 28.

- see INT 21,62 (Get PSP segment) for DOS 3.x applications