VIRTUAL MACHINE ACTIVITY The TRACE command allows you to trace certain virtual machine activities
and record the results on either your terminal or the virtual printer,
or on both. You can trace anv one or more of the following virtual machine
activities: • SVC interruptions • 1/0 interruptions • interruptions • External interruptions • privileged instructions • instructions • Successful branches Whenever vou are recording trace output at your terminal, the virtual
machine stops execution and enters the CP console read environment after
each output line. This is the default mode of operation when, for
example, you enter:
trace all
-- or
trace svc program branch
If you only want to record the trace and not stop after each output
line, add the RUN operand as the last entry on the command line.
If, havinq specified multiple activities to be traced, you decide to
stop tracing one or more of them, enter:
trace program branch off
and tracinq is now confined to SVcs only.
To trace all activity with the output directed to the virtual
printer, enter: trace all printer When you stop tracing, you must also issue the CLOSE command to print
the spooled trace output on the real printer: ttace end
close printer
If your virtual machine configuration contains only one printer,
trace output is intermixed with application You should define
another virtual printer with an address lower than the previously
defined printer. Application output is still directed to the original
printer; however, trace output is always directed to the printer with
the lowest address. For a complete description of the TRACE command
alonq with the trace output formats, see discussion of the command in
section 5. While trace is running, portions of virtual machine assist are disableds When the trace is complete, they are enabled. For more
information, see the TRACE command discussion in section 5. Section 3. CP Command Usage 33

34 VM/370 CP Command Reference for General Users