12MKQCN, If NORET or DEFRET specified, build and stack CPEXBLOK to alert the
interruption handler and return via EIIT SVC otherwise go to
specified interruption handler. Entry via SVC to disconnect and logoff a virtual machine as a result of transmission line failures. Place the virtual machine in a wait
state, VMRSTAT=VMCFWAIT. DMKSCHDL virtual machine to unrunnable state. DMKFREE for message for the system operator. DMKSCNRN, DMKSCNRD, DMKCVTBH, DMKSYSNM - FiII-in-message variables. -------- Fill in message variables. Send the user disconnect message to the operator. 12!!!2CN, Build TRQBLOK, if needed, for 15 minute delay, schedule it, and exit
via SVC. !2!!!2£!, After time elapse, TRQBLOK is unstacked and VMOSTAT is set to VMKILL for inevitable DMKUSOFF logoff operation. DMKDSPCH dispatcher.
3104/3105 INTERRUPTION HANDLER !2!!KRNH!£ Entry via DMKQCN or via CPEIBLOK for 3104/3105 resource
initialization. Locate the NICBLOK and check resource avaiability. For resource unavailable, set RC=12 in CONTASK save area and return
task via DMKQCNET. DMKRNH, For resource available, set CONTASK values per input and output task requirements. 12!!KR!]!, Move CONTASK from RDEVBLOK chain to NICBLOK chain. DMKRNH, RNSTART ---on-3104/3705 available condition, search NICLIST and build an IOBLCK if required. DMKRNHIC, RNEXLST ---search the-NICBLOKs for CONTASKs to be sent to 3104/3105, build and
chain for output. 1211KRN]!, RN£J!!!! Perform necessary function for each resource. Start output I/O operations. 121!KRNJ!, !U!l£J!!l Return via R1. Entry via SVC to schedule resource control tasks. 12MKRNH, RNH!12!! Build control CONTASK and enqueue it for execution. 12!!!R!!J!, For NORET specified, build and stack a CPEIBLOK to perfor. SVC exit. 12MKR!1!, RNDE!l! Attempt to start output via GOTO DMKRNHIC. RI.!!, Entry for 3104/3105 recovery. CP Method of Operation and Prograa Organization 1-199

DMKNLDR the 3104/3105, if it was not previously loaded. DMKF!l! Get storage to build CKPBLOK (telecommunications control block), if
necessary. Record active line and enabled terminal flag bits. Clear CONTASK chains. Force disconnect to all active users. DMKNLEMP ---nU8P-the 3104/3705.
DMKNLDR ---aeload the named program. On "IPL complete" signal, reenable resources.
DMKFRET ---aelease the CPEXBLOK. Exit to dispatcher. Q1!KRNl!!!! Entry via IOBLOK to perform input and output interruption processing. DMKRNK, RNIOERR ----For input-process failure. Analyze the failure and if related to the
3104/3705 and not to a particular resource, either retry or dump and
reload. Interpret response codes for each BTU received and schedule necessary
control operations. DMKR!1!, Generate response to a read error. Generate response to a write error. DMKRNJJ, Generate response to a contact task error. Generate response to a disconnect task error. Generate response to a control task error. Generate response to a unsolicited read. Return completed CONT1SKs. Attempt to restart the 3104/3705. DMKDSPCH the dispatcher. DMKRNHIN ---Entry via IOBLOK to perform input and output interruption processing. DMKRNH, SCHREAD interrupt status per IOBLOK values and if ATTN, build and start a read CCW sequence. If unit check and fatal, du.p and reload the 3704/3705. If pending ATTN cleared via 510 - Reschedule write operations. If unit exception, set RDEVSLOW and reschedule rejected CONT1SKs. Return only CONTASKs without CONRESP or CONSPLT set. Retain others
until final response is received.
1-200 IBM VM/370 System Logic and Problem Deteraination--Voluae 1