Section 8: Programming Basics
Interrupting Program Execution
Occasionally you'll want a program to stop executing so that you can see an
intermediate result or enter new data. The hp 12c platinum provides two functions
for doing so: gu (pause) and t (run/stop).
Pausing During Program Execution
When a running program executes a gu instruction, program execution halts
for about 1 second, then resumes. During the pause, the calculator displays the last
result calculated before the gu instruction was executed.
If you press any key during a pause, program execution is halted indefinitely. To
resume program execution at the program line following that containing the
gu instruction, press t.
Example: Create a program that calculates the entries in the AMOUNT, TAX,
and TOTAL columns for each item on the jewelry distributor's invoice shown on the
next page, and also calculates the total in each of these columns for all items on
the invoice. Assume the sales tax is 6.75%.
To conserve lines of program memory, instead of keying in the tax rate before the
b instruction we'll store it in register R
and recall it before the b instruction.
Before storing the program in program memory, we'll calculate the required
amounts for the first item on the invoice manually. The keystroke sequence will use
storage register arithmetic (described on page 29) in registers R
, and R
calculate the column sums. Since these registers are cleared when fCLEAR² is
pressed, we'll press those keys before beginning the manual calculation — and
also later, before running the program — to ensure that the column sums are
"initialized" to zero. (Pressing fCLEARH would clear registers R
but would also clear R
, which will contain the tax rate.)