YC!££l On completion of I/O operation, set appropriate status for command
reject, not ready protection check, incorrect length, channel program check. Set appropriate CC and CSW in users page o. Otherwise post
pending interruption status in YMBLOK, YCHBLOK, VCUBLOK, and VDEVBLOK. If command chaining, process the next ccw. DMKDSPCH -- Exit-to dispatcher. LOCAL GRAPHIC I/O AND INTERRUPTION PROCESSING Entry for local graphic device enable and disable function (from DMKCPVEN unstacked CPEXBLOK) Invoking CP ENABLEjDISABLE commands, start or terminate local 3270 display (and supported print
devices) and certain system console activity. DMKFREE ---Performs enabling function. Gets storage for IOBLOK and TRQBLOK
generation. Form and write out the logo at the screen. DM!2ll, ATT!!!!!! Unsolicited attention for RDEVBLOK (enabled). DMKBLDVM ---Suila LOGON VMBLOK for logon process. Enter console function mode for terminal input. DMKIOS2! Schedule request to clear screen preparatory to logon. DMKDSPCH dispatcher to wait for interruption. Successful logon per
the next interruption begins the operation of building the user's
virtual machine. DMKSCNRU -- From- the IOBLOK, locate the real device blocks related to the
interruption. Analyze IOBLOK CSW and condition code and the I/O operation to determine read/write sequential action. For unit error, retry 10 times (if applicable). If recovery fails, log off. For
ATTN interruptions, attempt to log on the new user if unsolicited
ATTN occurs. Otherwise, set up for READ CCW string. DMKFREE ---aet-storage for function and build CONTASK, IOBLOK, TRQBLOK. Issue the SID. DMKDSPCH ---Wait-for the response. DMKGRFIN ---rociI 3270 display and certain system console interruption entry from dispatcher. On response of CE and DE, go to auxiliary processing
routine address in TRQBLOK extension TRQBCRT and execute the
processing routines: !.Q.Y:t:!.ru! CONRETBF RD8INT GRFCF! SETREJ SETMOR SETWNG RDEXIT STRTREAD NOCTL Function completIon of a write CONTASK Completion of a buffer read
Execute console function Set no accepted tiaer Set more ••• timer delay Set 10 second clear warning
Clear bufferS after PF keys Set read status Process next CONTASK or go idle CP Method of operation and Program Organization 1-193

DMKGRF, RDATA ---Process-read response of data plus ENTER key. DMKCNSED modify length count. Move data to caller's buffer. Schedule rewrite to screen (unless inhibited) • QMKIOS2R Perform start I/O. DMKDSPCH dispatcher. DMKGRFIC ---intry point to process CONTASKS queue for local 3270 and 3066 devices.
DMKFREE for IOBLOK and TRQBLOK.
DMKGRF, BLDCCWS if appropriate. If not - DMKDSPCH dispatcher. DMKGRF, RDMINT read-return, determine function key action and write response (if
appropriate) via KEITEL.
DMKGRFTI point for processing timer interrupts. LOCATE AND VALID1TE AN 151M READ SEQUENCE Entry from D!KCCW modules to locate and modify an lSI! CCW string. Using the IOBLOKs IOBC1W locate the RCWT1SK. Check for the lSI! read CCW. CHK!Q Check for the correct 151M sequence as follows: 1. The last CCW in the RCWTASK is a TIC. 2. This RCWTASK points to the next RCWT1SK with a minimum of 2 CCWs. 3. The first modified CCW is in real storage.
4. The last byte of the 151M read overlays the operation code of
the first CCW in the next RCWT1SK. 5. The TIC in the RCWT1SK is to the next RCIT1SK's first CCW. 6. The date address of the first CCI in the next RCIT1SK is the same address of the lSI! read+1 as it is in real storage. DMKFREE ---Storage obtained for seven double words save block. DMKISM, CHKTSK2 -- Institute-the 151M read modification as follows:
1. Set the read to point to the save block data area.
2. Set the CP TIC to point to the modified CCI in the same block.
3. Set the modified CCI (seek head) in the save block to point to
the save block data area.
4. Set the CP TIC in the save block to return to the RCIT1SK following the modified (seek head) CCW. 5. Set the search cel in the RCWTASK to point to the data area in
the same block.
1-194 IBM VM/370 System Logic and Problem Deter.ination--Volume 1