HP·38E/38C - Slide Rule Museum

94 Writing a Second Program
For example, to see line 04 in the previous program, press (]] [GTe I. 04
so that the display shows:
04- 51
When using the [GTe 1 key in this way, always use two digits for
designating line numbers (01 through 99). If you attempt to go to a line
number that is not within memory as currently described by (]] [ MEM 1
the calculator will display Error 4 .
Try to go to line 56 of program memory:
Keystrokes Display
(]] 1 GTe 1 • 56 Error 4
This means that you have attempted to go outside the current allocation
for program memory. You saw earlier that the calculator gives you eight
program lines to start writing your program. Don't worry-if you have a
long program and really do need to see line 56, the calculator will let
you do it.
Now, pressing any key will clear the error message from the calculator
and return it to the original display.
If one of the two keys following [GTe 1 is not a digit entry key , the [ GTO 1
key is ignored and the operation associated with the invalid key is
recorded .
Interrupting Program Execution
From time to time you will want a program to stop execution by itself
so that you can enter new data or view an intermediate result. (In our
invoice example, we would like to see the intermediate results for
TOT AL and TAX so that they may be recorded.) There are two
operations on your HP-38E calculator that will automatically interrupt
program execution when they are encountered as program instructions:
(]ill (run/stop) and 1 PSE 1 (pause).
Stopping Program Execution
(]ill works differently as an executed instruction in a program than it
does when pressed from the keyboard in run mode. As an executed
instruction, (]ill stops program execution, allowing you to key in new
data or to write down an intermediate result.
When (]ill is then pressed from the keyboard in run mode, the calculator
resumes program execution sequentially downward.