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ALTPRT (PRT)
Program Trace Routine
Sends all trace printout to an alternate print file while command solicitation,
command responses (as for DUMP, for example), and all program print requests are
sent to the terminal as usual. One parameter may be entered that is the name of
the file to be used as an alternate print file. If the file specified is not assigned,
SNOOPY automatically assigns a temporary file. (If the file will be printed by the
@SYM statement, it must be assigned as cataloged rather than temporary.) If the
program traced uses alternate symbiont files, the restrictions on the maximum
number of alternate files that are allowed open must be followed.
The ALTPRT command gives control of the alternate print files. In general, the
ALTPRT command uses an alternate file and the current alternate file is breakpointed
(@BRKPT). This action may be suppressed by using an asterisk (*) as the trailing
delimiter for the parameter (for example, either “ALTPRTfilename*” or
“ALTPRT *”).
To obtain printouts both at a terminal and in an alternate file, the ALTPRT filename
should have a trailing exclamation point (!), (for example, “ALTPRTfilename!”). This
is useful for obtaining a permanent record when working at a terminal that lacks a
hard-copy capability. If an alternate file is already active, the command forms
“ALTPRT !” and “ALTPRT ?” may be used to set and clear echo mode while leaving
the same alternate file in use. Echo mode is always cleared when the trailing
exclamation point is not used. Therefore, to start a new alternate file without
breakpointing the old file and with echo mode set, use the command sequence
“ALTPRT* ALTPRTfilename!”.
If the parameter is omitted (as in “ALTPRT/”), printing is directed to the terminal as it
is initially. This command is effective for all SNOOPY operations until another
ALTPRT command is given or the program being traced terminates. This command
forces the location counter element name printout to be given so that each piece of
printout may be easily identified.
BREAK
The BREAK loc-1, loc-2,... command indicates a stopping point for SNOOPY when
operating in trace mode. When any specified address is reached, the trace stops
and SNOOPY enters command mode. This command is useful for running with
printing turned off. Use the form BREAK+ to add entries to the existing table. A
maximum of 16 addresses is permitted. Use the $ specification to retrieve the last
address returned by the ABSAD command. The form BREAK? lists the table of
break addresses. The command BREAK may be abbreviated to just the letter B.
This form of the BREAK command is incompatible with the previous form. The
change is made for reasons of efficiency and utility; the break on element name or
location counter was seldom used but introduced considerable overhead for each
instruction traced, while it was impossible to have more than one break active at the
same time. Determine which form of the BREAK command is available in SNOOPY
by entering the BREAK command without parameters on the same line (or a “/” to
indicate no parameters). The old form of BREAK solicits input with “ELT NAME--”,
whereas the new form requests input with “LOCN--”.
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