IBM System/370 145 Manual page 157

precision operations. (The extended prec1s1on simulator, which
simulates all the operations pro'vided by extended precision instructions
and extended precision divide as well, is automatically included in all
operating· systems at system genel['ation time.) Extended precision divide
is always simulated, since the e:~ended precision hardware feature does
not include such an instruction.
Monitoring feature. This feaiture is supported by the Generalized
Trace Facility (GTF). GTF is a
=~tandard
feature of MFT and MVT for
System/370 and System/360 models,. GTF uses the monitoring feature when
the feature is present and simulates its function when monitoring
hardware is not available.
An ~3sembler
Language
mnemo~ic
is also
provided for the MONITOR CALL inl:ltruction.
GTF offers a generalized
trac4~
function, which supports more options
than the existing
os
trace facility, and a new trace edit function.
When trace data is placed in a brace output data set instead of being
maintained in processor storage, the trace edit function, a feature of
IMDPRDMP which is invoked via job control and operates as a processing
program, can be used to format and print the trace output. Options
include printing of selected evellt classes, selected events within event
classes, events associated only
~l1ith
a specific job, and events that
occurred after a specific time. The trace edit function requires a
minimum of
4LJK
in which to execu1:e.
The generalized trace functioll is invoked as a system task by the
operator via a START command. The trace function continues until
terminated by a STOP command.
~len
the generalized trace function is
active, operation of the current OS trace facility is suspended, if it
is present.
The generalized trace functioll supports tracing of all or any
combination of the following:
• All I/O interruptions, all non-PCI interruptions, or only I/O
interrupt:ions from specific devices
• All START I/O operations or only START I/O operations for specific
devices
• All SVC interruptions or onllr interruptions for specific SVC codes
• All program interruptions or only interruptions for specific program
interruption codes
• All external interruptions
• All entries into the dispatcher routine of the control program (for
tracing the flow of routine E~ecution)
• All user-supplied trace entries (discussed below)
• Events associated with the tz"ace task
Events that occur in user-writ~ten routines can be monitored by use of
the new GTRACE macro, which will expand into a MONITOR CALL instruction
when used on the Model 145. Execution of this macro causes a user-
supplied trace entry, containing the data presented via ~he macro, to
be
included in the trace output.
Interval timer. The interval timer is supported for the same
functions as i t is for System/360 except for time of day values.
A Guide to the IBM System/370 Model 145 147