Program Logic Manual - All about the IBM 1130 Computing System

SECTION 7. CORE IMAGE LOADERFLOWCHARTSPhase 1: CIL01Phase 2: CIL02PHASE 1Phase 1 of the Core Image Loader handles the threeentries to the Skeleton Supervisor - LINK, DUMP,and EXIT, The Core Image Loader is assigned thistask in order to minimize transfer time (via CALLLINK) from one link to another.Phase 1 of the Core Image Loader is naturallyrelocatable. It is read into core storage by theSkeleton Supervisor immediately following whicheverdisk I/O subroutine is currently in the ResidentMonitor. (This can be done by the Skeleton Supervisorwith minimal core requirement because theword count and sector address of this phase permanentlyreside at the end of each disk I/0 subroutine.)If the Skeleton Supervisor was entered at$DU1V1P ($RMSW is positive), phase 1 tests$DUMPF, the dump format code indicator. If$DMPF is negative, phase 1 fetches and transferscontrol to the Auxiliary Supervisor. If $DMPF isnot negative, phase 1 fetches and transfers controlto the System Core Dump program.If the Skeleton Supervisor was entered at $ EXIT($RMSW is negative), phase 1 tests $DZIN to determinewhether DISKZ is in the Resident Monitor. IfDISKZ is in the Resident Monitor, phase 1 fetchesand transfers control to the Monitor Control RecordAnalyzer. If DISKZ is not in the Resident Monitor,phase 1 fetches phase 2 of the Core Image Loader.Using phase 2 as a subroutine, phase 1 overlaysDISK1 or DISKN with DISKZ.. Phase 1 then fetchesand transfers control to the Monitor Control RecordAnalyzer.If the Skeleton Supervisor was entered at $LINK($RMSW is zero), phase 1 tests $COMN in COMMAto determine if COMMON was defined by the coreload just terminated. If $COMN is non-zero, phase1 saves Low COMMON on the CIB. (Low COMMONis the lowest 320 words that could have been definedas COMMON by the core load just terminated.)Depending on the disk I/O subroutine currently inthe Resident Monitor, Low COMMON is defined asfollows:Low COMMONDisk I/0 Subroutine Decimal HexadecimalDISKZ 896 - 1215 /0380 - /04BFDISK1 1216 - 1535 /04C0 - /05FFDISKN 1536 - 1855 /0600 - /073FThe area occupied by Low COMMON is used byphase 1 as a disk I/O buffer during the LET/FLETsearch and/or as the area into which phase 2 isfetched when phase 2 is to be used to fetch DISKZ.Once Low COMMON has been saved, or if noCOMMON was defined by the core load just terminated,phase 1 searches LET/FLET for the nameof the program or core load to be executed next.The name of tile link has been saved in $LKNM by theSkeleton Supervisor.If the link is in disk system format (DSF), phase1 saves any COMMON defined below 4096 on theCIB. It then fetches phase 2, uses phase 2 as asubroutine to overlay DISK1 or DISKN with DISKZ,fetches phase 0/1 of the Core Load Builder, andtransfers control to phase 1 of the Core LoadBuilder.If the link is in disk core image format (DCI),phase 1 fetches and transfers control to phase 2 tofetch the link and the required disk I/O subroutine,if necessary, and to transfer control to that link.Special Techniques. Phase 1 of the Core ImageLoader places a disk call subroutine in COMMA at$HASH+8 through $HASH+19. Using this disk callsubroutine, phase 1 is able to overlay itself whenfetching phase 2, the Monitor Control RecordAnalyzer, etc.PHASE 2Phase 2 of the Core Image Loader is naturallyrelocatable. It is read into core storage (by phase1) immediately following the end of phase 1 if it isto be used by phase 1 to fetch DISKZ, or (by eitherphase 1 or the Core Load Builder) following the endof the disk I/O subroutine currently in the ResidentMonitor if it is to fetch and transfer control to acore load. Phase 2 provides two functions: (1)to overlay the disk I/O subroutine currently in theResident Monitor with the requested disk I/O sub-Section 7. Core Image Loader 27