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Program Trace Routine
CAPTUR
Enters SNOOPY from ordinary program execution mode whenever control reaches
any of a specified set of addresses. The instructions at the specified addresses are
overlaid by a jump to a SNOOPY internal table area, where an SLJ TON$ is
performed, followed by the overlaid instruction. The overlaid instruction may not be
referenced as data by the program, but there are no other restrictions. The syntax of
the command is CAPTUR loc-1,loc-2,..… Up to eight locations may be specified,
separated by commas. Any existing list is replaced by the new list (with the overlaid
instructions restored). If CAPTUR+ is used, the specifications are added to the
existing table, again up to a total limit of eight. Use CAPTUR? to print out the
contents of the table.
When using this command with segmented or multibanked programs, take care that
the specified capture locations are in main storage when they are changed. The
locations must not reside in a read-only bank. The purpose of this command is to
provide the fastest possible means of getting past a portion of the program that is
irrelevant to the debugging task. The use of external symbols is subject to the
restrictions noted for the ABSAD command. See CHANGE command for use of the
symbol $.
CHANGE (C)
Allows the caller to change the contents of control registers or main storage. The
single parameter specifies the location to be changed. After reading the location
parameter, the contents of the specified location are displayed as if the location
parameter had been given to a DUMP command; then the new value is solicited.
The new value is stored and the new contents displayed. A void new value does not
change the indicated main storage element.
If the parameter is a register name, a number, or a number or register name
preceded by an H or Q, the new value is to be entered as a single octal number.
The CHANGE command allows the caller to use mnemonics and external symbols
for I format (instruction format) changes, as well as octal values. The first item given
to “NEW VAL--” may be an op-code mnemonic instead of an octal number for the
f-field of the instruction. Abbreviated forms such as L, LN, ANM, etc. are not
permitted; however, LX, LA, LR, LNA, ANMA, and so on must be used.
For some instructions, the op-code mnemonic specifies values for the j-field and
perhaps the a-field as well. In such cases, the next value given to the CHANGE
command is an a-field or an x-field. Mnemonics may also be used for the
j-designator values (W, H1, H2, XH1, XH2, T1, T2, T3, S1, S2, S3, S4, S5, S6, Q1, Q2,
Q3, Q4,U, and XU) and for standard X, A, and R register names. If a register name is
used in the a-field of an instruction, its value will be adjusted appropriately.
Truncation errors are not detected.
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