It turns out the KA ITS machines have an instruction that does roughly the same thing, but it's different. Here's the relevant code fragment from SYSTEM;ITS >: IFN KA10P,[ SUBTTL STUFF PECULIAR TO KA-10 PROCESSOR ;;;PAGING BOX INSTRUCTIONS LPM=102000,, ;LOAD PG MEM STATE VECTOR DONT CLR ASSOC MEM LPMR= LPM 2, ;CLEAR ASSOC MEM AND LOAD SPM= LPM 1, ;STORE PG MEM STATE VECTOR LPMRI=LPM 6, ;LOAD PM, CLEAR ASSOC REG, AND CAUSE INTERRUPT EXPGNG==4 .SEE UPQUAN ;4 TO TURN ON EXEC PAGING XCTR=103000,, ;EXECUTE INSTRUCTION WITH MAPPING CONTROLLED BY AC FIELD ;VIOLATION CAUSES USER MEM PROTECT INTERRUPT UNLESS INHIBITED ;VIOLATION ALSO SKIPS BUT THIS IS OF NO CONSEQUENCE UNLESS ;INTERRUPT IS INHIBITED SINCE PC WILL BE RESET FROM OPC XCTRI= XCTR 4, ;XCTR WITH PAGE FAULT INHIBITED (SKIPS ON FAULT) ; AC FIELD VALUES FOR XCTR AND XCTRI XR==1 ;MAP READ MAIN OPERAND OF SIMPLE INSTRUCTION (MOVE, SKIPL, HLL) XW==2 ;MAP WRITE MAIN OPERAND OF SIMPLE INSTRUCTION (MOVEM) XRW==3 ;MAP READ/WRITE OPERAND OF SIMPLE INSTRUCTION (E.G. IORM) XBYTE==3 ;MAP BYTE DATA AND BYTE POINTER (ILDB, IDPB) XBR==1 ;MAP BLT READ XBW==2 ;MAP BLT WRITE XBRW==3 ;MAP BOTH OPERANDS OF BLT ;KA10 PAGING BOX GOES BY WHETHER IT'S A READ OR WRITE (OR RW) CYCLE ;KL10 PAGING BOX WORKS DIFFERENTLY (SEE BELOW) ;DO NOT USE MULTI-OPERAND INSTRUCTIONS (DMOVE, PUSH, ETC.) WITH XCTR The KL and KS are both different (although both use XCTR and XCTRI); the KL stuff is later down in that file; the special KS instructions are in KSHACK;KSDEFS > if anyone wants to look at them. Noel