Any normal activity or event in the system Wait state Stopped state Instruction-step mode Single-cycle mode Test model System reset Initial program load procedure
If TaD clock hardware errors occur, the System/370 hardware posts a
machine check and CP enters a disabled WAIT state.
The current clock value can be obtained by using the System/370 STORE CLOCK instruction, which causes the current clock value to be stored in
the storage location specified in the instruction. Thus, virtual
machines can use the value of the TOD clock for any purpose that their
users desire. However, virtual machine users cannot set or modify the
TaD clock.. V!/370 uses the TaD clock for establishing certain
accounting records for the virtual machines as well as queueing and
prioritizing tasks for CP and virtual machine operations.
The privileged System/370 instruction, SET CLeCK, sets the clock to a
specific value. If certain operating or program conditions exist, CP executes this instruction when the system is initialized. When this
instruction executes, it replaces the current clock value by the value
specified in the instruction. The SET CLOCK instruction changes the
clock value only when the TOD ENABLE SET switch is enabled.
If the inst?llation is configured with an attached Frocessor, it may be necessary 1n the initialization procedure to synchronize the TOD clocks. When this occurs, you may be requested to ready the "TOD ENABLE SET" key twice; once to set the clock on the main processor and once to "SET and SYNC" the clock on the attached processor. If the clock value
has previously been established for the main then only one proapt message will be issued. Note, that the TOD Enable Set key is
or'd to the other processors' TaD Enable SET key. This permits the
setting of the clock from either processor. If the low-order 32 bits of
the TaD clock are out of synchronization, a TOD Sync check will be
received. Again, you will be requested to synchronize the TOD clocks by pressing the TaD Enable Set key.
Details on those segments of V!/370 initialization that
only to attached processor applications are detailed at the System Initialization topic.
are unique
end of the
If the clock needs to be set, CP prompts you to enter the date by
issuing the message: SET DATE !!/DD/YY: You should then enter the date. CP then requests the time: SET TI!E HH:!!:SS: You should then enter the time. IThe current clock value is lost when the time-of-day microdiagnostic
tests are being run, or when system power is turned off. Sectiori Initiating Vft/370 Operation 11
1. Enter the required data immediately following the colon (:). If
you are using a 3210 or a supported CPU display console,
enter the information in the user input area. The information then appears in the output display area on the line fclloving the SET TIME r.equest.
2. You should enter a time value that is some 30 to 60 seconds ahead
of the current time, because CP requests you to press the TOD ENABLE SET switch when setting the clock.
For example, if the date is 03/01/14, and the time will soon be 08:28 (EST), the exchange on a printing terminal looks like this: VERSION 1 LEVEL 0 mm/dd/yy SET DATE 88/DD/YY :03/01/14 SET TI8E HH:88:SS :08:28:00 PRESS "TOD ENABLE SET" KEY AT DESIGNATED INSTANT When you press the TOD ENABLE SET key, CP responds with: NOW 08:28:00 EST FRIDAY 03/01/14 CHANGE TOD CLOCK (YESINO): !Qte: The previous example executed on a display terminal would show
your responses on separate lines. You now have an opportunity to change the value of the clock. If you
enter "no", or press the END function key on the console, clock
initialization ends. If you enter "yes", another series of prompting messages permit you to enter a new date and time. To V8/310 users, the epoch clock value of all zeros
indicates the beginning of the day January 1, 1900. To OS and OS/VS users, the epoch clock value of all zeros represents the beginning of
the day January 1, 1960. Thus, OS virtual machine users will find that
stored clock values differ by 60 years; however, it is possible in OS to
use 1900 as the base epoch clock value.
Cold start procedures are usually invoked only on
operation of a new version of the VM/370 system or
files. as well as accounting records are lost or
because of a hardware error that prevented valid
continuation.
the initial loading
if all closed spool
rendered unreadable system recovery and
Failures in system component power, building power, hardware logic,
the CP program, or some (rare) kinds of user programs can be classified
as system operating procedure errors; all can require that you start the system with a cold start. Some of these malfunctions may require you to
issue the SHUTDOWN command. If the SHUTDOWN co.mand cannot be keyed in,
you can press the LOAD button on the System/310 console. Then after the
appearance of the shutdown message, you should the LOAD button a
second time to reload the system with V8/310. V8/310 issues a message
to you to perform cold start procedures when it recognizes that
unrecoverable errors have occurred.
12 V8/370 Operator's Guide
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