Type ASSEMBLE
Source Lines : 705
Fixes Applied : 9
Most Recent Version : Wednesday, December 13, 1978
Last Fix ID : [HRC004DK]

Module

       DMKPSA

Function

       TO PERFORM THE APPROPRIATE ACTIONS FOR VARIOUS
       TYPES OF EXTERNAL INTERRUPT CODES.

Attributes

       SERIALLY REUSABLE, RESIDENT

Operation

       EXTERNAL INTERRUPTIONS ARE HANDLED AS FOLLOWS:

       1.  IF THE EXTERNAL INTERRUPT WAS FROM THE RED "INTERRUPT"
       KEY ON THE 370 SYSTEM CONTROL PANEL, THE NECESSARY STEPS
       (INCLUDING A CALL TO DMKQCNCL) ARE TAKEN TO CLEAR AND
       DISCONNECT THE SYSTEM OPERATOR'S TERMINAL (IF HE IS LOGGED
       ON, AND NOT ALREADY DISCONNECTED).  THE SYSTEM OPERATOR IS
       THEN ABLE TO LOG ON OR BE RECONNECTED AT ANY OTHER TERMINAL,
       VIA THE 'LOGON' COMMAND. THE BUTTON INTERRUPT IS IGNORED FOR
       ANY PROCESSOR OTHER THAN THE MAIN PROCESSOR IN AP SYSTEMS.

       2.  IF THE EXTERNAL INTERRUPT WAS DUE TO A TIMER INTERRUPT,
       THE MACHINE MODE IS DETERMINED, AND ACTION TAKEN AS FOLLOWS:

            A.  IF THE MACHINE WAS IN PROBLEM MODE, THE ADDRESS OF
            CURRENT USER'S VMBLOK IS OBTAINED FROM RUNUSER. THE
            USER'S VIRTUAL PSW (VMPSW) IS UPDATED FROM THE EXTERNAL
            INTERRUPT OLD PSW AND THE ADDRESS OF THE CURRENT VMBLOK
            IS LOADED INTO GPR-11.

            B.  IF THE EXTERNAL INTERRUPT IS FROM THE CPU TIMER
            AND THE VIRTUAL CPU TIMER IS CONTAINED IN THE REAL CPU
            TIMER, A CALL IS MADE TO DMKTMRVT TO PROCESS THE
            INTERRUPT. IF THE REAL CPU TIMER DOES NOT CONTAIN THE
            VIRTUAL CPU TIMER, A FLAG IS SET IN THE VMBLOK INDICATING
            THAT THIS USER'S TIME SLICE HAS BEEN EXCEEDED. CONTROL IS
            THEN PASSED TO THE DISPATCHER.

       3. IF THE EXTERNAL INTERRUPT WAS DUE TO THE TIME OF DAY
       CLOCK COMPARATOR, THE ACTIVE TIMER REQUEST QUEUE BLOCK
       (TRQBLOK) IS STACKED FOR EXECUTION VIA DMKSTKIO. FOR A
       UNIPROCESSOR SYSTEM THE CLOCK COMPARATOR IS RESET FROM THE
       FIRST TRQBLOK ON THE QUEUE. FOR AN ATTACHED PROCESSOR SYSTEM
       THE COMPARATOR IS RESET FROM THE FIRST TRQBLOK NOT ALREADY
       ACTIVE ON THE OTHER PROCESSOR. CONTROL THEN TRANSFERS TO
       THE DISPATCHER.

       4. FOR EXTERNAL INTERRUPTS DUE TO EXTERNAL CALL, EMERGENCY
       SIGNAL, TOD SYNC CHECK AND MALFUNCTION ALERT, CONTROL IS
       TRANSFERRED TO DMKEXTSL.

       THE DMKPSARX, DMKPSARS, DMKPSARR, AND DMKPSAID
       ENTRY POINTS ARE DESCRIBED IN A FOLLOWING SECTION.