HP 9835A Programming Manual page 191

Debugging
171
To permit you to analyze the execution of assembly language routines, an executable BASIC
statement has been provided -
Now, should you have the sequence in your program -
:L 1 0 I F'HU
'::;E
()H
, . . . F'
Ie H L.L ' : ::;
'··if .1-. ::.
i:::: .:: ,:,:. ::. ::.
then pressing
8
during the execution of line 120 would cause program execution to be
interrupted after completion of whatever machine instruction is being executed at the time.
Further, the assembly language source line associated with the following instruction is dis-
played according to certain rules.
If the source lines are still in memory when you press
8
(e.g., you just assembled the object
code which you are running), then the source line is displayed. If the source is no longer in
memory (e.g., the object code was obtained through an ILOAD), then the instruction displayed
is the result of a "reverse assembly". If there is an operand with an instruction which is reverse
assembled, then the octal value of that operand is displayed (this is because the reverse
assembly process has no way of knowing what symbols you might have used to assemble the
instruction originally).
After pressing
8,
should you press
B,
execution resumes normally. It is notnecessary for
you to do anything (such as cleaning up the registers, etc.) for execution to resume as if you had
never interrupted it.
After pressing
8,
you may want to observe the flow of execution of your assembly routine.
This can be done by successively pressing the
@ill
key. Each time the key is pressed, another
machine instruction is executed and the assembly source line associated with the next machine
instruction is displayed. You may continue this way for as long as you like - until you press
B
to allow processing to proceed uninterrupted until the end of the routine.
Of course, the
@ill
key can be used to step through the BASIC program as you are used to
doing. That feature is unchanged. It is possible, therefore, to "step into" the assembly lan-
guage routine from the BASIC (Le., you need only
@ill
into line 120 above) and not have to
use the
8
key at all.