IBM System/370 145 Manual page 207

recovery that occurred, identifica1tion of the job, job step, and program
involved in the error, the date, alll,d the time of day. MCR schedules the
writing of the recovery report record and informs the operator that a
machine check has occurred.
MCH supports an operator MODE command that can be used to enable the
CPU for interruptions after
inter~ittent
single-bit error corrections.
The operator can establish full :cec:ording mode for intermittent single-
bit processor and/or control storaqe ECC corrections. These corrected
errors will then be recorded and the operator will be notified. The
operator can also reestablish quie1t. mode for processor storage
corrections and threshold mode for control storage corrections. (The
operator is notified when a switch from threshold to quiet mode is made
for control storage corrections.) In addition, the operator can
establish quiet mode for control s1:.orage corrections.
A capability for the operator to switch to quiet mode for successful
microinstruction retries is not provided, as is discussed for the DOS
MCAR routine; thus, recording always occurs for these errors.
'I'he operator also is informed
oj:
the occurrence of a Timing
Facilities Damage or an Interval Timer Damage machine check
interruption. Error recording is performed, after which the system is
placed in a wait state if a timing facilities error occurred. System
operation continues after an interval timer error. (See Figure 50.10.5
for the general flow of OS MCH pro(:essing after repressible machine
check conditions.>
Exigent Machine Checks. When an Instruction Processing Damage
machine check occurs (uncorrectablE~ or unretryable CPU error, double-bit
processor or control storage error" or storage protect key failure>, MCR
assesses the damage.
MCH attempts to identify the task associated with the error so that
the task can be terminated abnormal.ly.
A
damage report record, which
contains both the fixed and CPU ext:ended logout area da+-.a, the recovery
action taken, the program identification, the date, and the time of day,
is prepared and logged. System OpE!r ation continues if the error task
associated with an uncorrectable error can be identified and terminated.
system operation halts and a re-IPI. is required if the error damages a
portion of the control program, or if the error cannot be associated
with a specific task. The operatoz' is informed of whatever action is
taken.
When a System Damage machine che!ck occurs, programmed recovery is not
possible, and MCR places the system in a wait state after a logout and
termination procedures are attempted.
The MFr and MVT MCH routine for the Model 145 contains model-
dependent routines and will not exe!cute correctly on System/3
6
0 models
or another System/370 model in Be mode. See Section 60:20 for a
discussion of operating system port.ability. (For a discussion of system
operation with an operating system without Model 145 RMS, see Section
60:35.)
Channel Check Handler
CCH receives control after
a
channel error causes an I/O
interruption. CCH formats both an error information block (containing
the limited channel logout data) for use by an ERP routine and a CCH
error record for recording in SYS1.LOGREC. The latter contains status
information from the logout area, the limited channel logout area,
program identification, date, and time of day.
A Guide to the IBM System/370 Model 145
197