INT E0 - REAL/32 - "P_PDADR" - GET ADDRESS OF PROCESS DESCRIPTOR
	CL = 9Ch
Return: ES:AX -> caller's process descriptor (see #04026)
	may destroy SI,DI
Note:	This function is also called by the DR DOS MEM utility when
	  INT 21/AX=4451h returns either 1463h (MDOS 5.00), 1465h (MDOS 5.01),
	  or 1466h (MDOS 5.10).
SeeAlso: INT E0/CL=8Fh,INT E0/CL=90h