Texas Instruments 990 Operation Manual page 86

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Character Trace Output
D
E
B
A
R
DE=XXXX
DB=XXXX
DA=XXXX
DR=XXXX
Description
Destination. Refers to the destination. It is followed by an E, B, A or R.
Destination effective address. This address is the memory address that the
destination field addresses. The destination effective address is only printed
for Format 1, 3, and 9 assembly language machine instructions. All other
instruction format types do not have a destination field (example 2).
Contents of destination effective address before statement executed. This is
printed whenever a destination field exists (example 2).
Contents of destination effective address after execution. This is printed
whenever a destination field exists (example 2).
Contents of destination workspace register after execution for Td
=
3 (in-
direct addressing with autoincrement). (Td is the destination addressing mode
field in an assembly language machine instruction.) The contents of the
destination register is printed
if
an autoincrement is specified.
Description: The character string is scanned for proper syntax. If the string conforms to the
syntax, a trace print control template is built and placed in the trace format table.
The character string in the ST command allows the user to select only those portions of the
trace output that he needs. For tutorial purposes, an extensive trace output could be requested,
while minimal traces such as a PC or variable trace are also easily selected. Each character in the
character string represents a desired portion of the trace.
If any trace option other than PC is printed, PC is also printed.
A variable trace (paragraph 3.4.26) is implemented by specifying the desired variable.
The character string is scanned from left to right. The characters E, B, A and R are modified by
the most recent occurrence of S or D.
If
E, B, A or R is encountered before an occurrence of S
or D, or if an invalid character is encountered, the scan is aborted and an invalid syntax message
is issued. A character string consisting entirely of S or D is also an invalid syntax.
All four trace format table elements have initial values as follows when the debug monitor
overlay containing the ST command is loaded:
Index Number
o
1
2
3
Equivalent Character String
P
PIWSEADEA
T
PIMWTCXSEBARDEBAR (all trace output options)
3-48
Digital Systems Division