Code I'OS' X'09' X'44' X'80' X'82' X'9C' X'9D' X '9E' X'9F' X'AC' X' AD' X· B l' X'B202' X'B203' X'B204' X'B206' X'B207' X'B208' X'B209' X'B20A' X 'B20B' X'B20D' X 'B6' X'B7' X'BA' X' BB' Q,Eeratio,!! SSK - Set storage key ISK - Insert storage key EX - Execute instruction SSM - Set system mask LPSi - Load PSi SID - Start I/O TID -Test I/O HID -Halt I/O TCH -Test Channel STNSM - store, then AND system mask STOSM - store, then OR system mask LRA -Load real address STIDP - Store processor ID STIDC - store channel ID SCK - Set TOD clock SCKC - set TOD clock comparator STCKC - Store TOD clock comparator SPT - Set CPU timer STPT - Store CPU timer SPKA - Set PSi key from address IPK - Insert PSi key
PTLB - Purge TLB STCTL - Store control registers
LCTL -Load control registers CS - Co.pare and swap CDS - Compare double and swap DMKPRV, The system lock must be obtained before other supervisor routines are
called. If the system lock is not immediately available, defer the
interrupt and exit to DMKDSPRU. DMKHVCAL ---on--Privileged operations of DIAGNOSE X'83' and the associated
function code, perform the service. DMKVSIEX privileged I/O operations of SIO, HIO, TIO and TCH. DMKTMRTN Perform privileged operations related to TOD clock, TOD clock comparator and the processor timer. DMKPRGSK Program interruption is reflected back to the user
instruction operands, unsupported instruction operand DIAGNOSE '83' function codes that are not a multiple of 4.
on invalid codes and Virtual I/O Operations and Interruption Processes
CTCA OPERATIONS BETiEEN TiO VIRTUAL MACHINES DMKVSIEX ---virtual I/O operation is reflected to DMKVCA, the channel adapter
module, for processing. For SIO, check if the CTCA is coupled. If not coupled, call DMKDIASM. DMKDIASM - Simulate return status. For a coupled CTCA, analyze operations resulting in X-side (read) and Y-side (write) of the data transfer operation. CP Method of Operation and Program OrganiZation 1-189

DMKVCA, VCASIOB ---netected-Interruptions are presented to users via stacked IOBLOKs and DMKSTKIO. CTCA TIO activity is determined by examining Y-side information to
determine mode and activity. DMKVCASH ---cTci-HIO and HDV is processed by determining the conition code to
present and whether the Y-side should be notified. CTCA process results from RESET xxx or SYSTEM RESET commands. The CTC! status is reset but the CTCAs are not uncoupled. DMKVCARS ---Uncoupling CTC! is achieved in the VDEVBLOK (VDEVNRDY flag) idle CTC!
plus an invoked DETACH xxx or user LOGOFF. Return to calling
routine. SCHEDULING I/O FOR CP AND THE VIRTUAL MACHINE Entered via SVC. Entry point indicate a CP I/O event as indicated in
the IOBLOK. For start request, increment the SIO count in the RDEVBLOK and start the device if it is available. If not (device
busy or already scheduled) queue the IOBLOK and return the operation
to the caller. Entered via SVC. Entry point indicates virtual machine initiated I/O event. Preserve VMBLOK address in Rll, turn off IOBCP bit in the IOBLOK, add 1 to SIO count in the VDEVBLOK (or RDEVBLOK). Process
the SIO if there is any available path to the device. If not, queue
the IOBLOK and return the operation to the caller. STANDARD DASD I/O INITIATED VIA DIAGNOSE DMKDGDDK ---perform si.ple disk I/O of a standard format. Entry is via DMKHVC code X'18'. DMKSCNVU ---rInd-device related to SIO cuu address. DMKFREE -- Allocate storage for IOBLOK and RCWTASK. DMKGDDK ---SuIld and check the CCW string. Execute I/O. On completion, post condition code (and error return
code in R15, if detected). DMKDSPCH dispatcher. 1-190 IBM 1M/370 System Logic and Problem Deter.ination--Voluae 1