HP·38E/38C - Slide Rule Museum

Section 8
Editing a Program
Even the most experienced programmer finds errors in his programs.
These errors range from mistakes in the original formulas to mistakes
in recording the program. Whenever they occur they need to be found
and corrected, and your calculator is designed to make this error-checking
process as easy as possible.
Finding the Error
One of the easiest ways to find out if your program is working properly
is to work a test case in which you either know the answer or the answer
can easily be determined. For example, if you have a program that
calculates the sum of several numbers and then finds the percent each
number is of the total sum, you can easily determine whether the program
works by entering all like numbers (for example ten 10's) so that the
percent total of each number is the same (10 is 10% of 100).
I SST I Execution
In longer programs a wrong test-case answer will seldom pinpoint a
mistake. For these cases, you can slow down program execution by
using I SST I (single step) in run mode. In run mode, I SST I will execute
your program instructions one at a time. When you hold the I SST I key
down in run mode, the program line number and keycode are displayed.
When you release the I SST I key, the instruction is executed. Use I SST I on
the program shown below to familiarize yourself with its operation.
Example Program: This program computes the net amount of an item
when the sales tax is 7% . Toggle into program mode and clear program
memory to display line 00. Then key in the list of keys shown below.
Keystrokes Display
IENTER_I 01- 31
7 02- 7
00 03- 23
CD 04- 51
118