HP HP-28S - Single-Step Execution

Single-Step Execution
It's easier to understand how a program works if you execute it step
by step, seeing the effect on the stack of each step. Doing this can
help you Udebug
U
your own programs or help you understand pro-
grams written by others.
This
section shows you how to execute FIB2 step by step, but you can
apply these rules to any program. The general rules are:
1. Use VISIT to insert the command HALT in the program. Place
HALT
where you want to begin single-step execution. (You'll see
how the position of HALT within FIB2 affects execution.)
2. Execute the program. When the HALT command is executed, the
program stops (indicated by the Ustopsign
U
annunciator).
3. Select the PROGRAM CONTROL menu.
4. Press SST once to see the next program step displayed and
then executed.
You can now:
• Keep pressing SST to display and execute sequential steps.
• Press
.1 ceNT I to continue normal execution.
• Press
KILL to abandon further program execution.
5. When you want the program to run normally again, use VISIT to
remove HALT from the program.
250 28: Programming Examples