HP·38E/38C - Slide Rule Museum

108 Decisions
How it works: The I GTO I 03 instruction causes the calculator to break
the sequential execution and resume from the new line.
Since execution is transferred to the instruction in line 03 each time the
calculator encounters the I GTO I 03 instruction in line 10, the calculator
will remain in this " loop," continually adding one to the number in
storage register R[ and displaying the new number and its square.
Looping techniques like the one illustrated here are common and
extraordinarily useful in programming. By using loops, you take
advantage of one of the most powerful features of your calculator-the
ability to update data and perform calculations automatically, quickly ,
and if you so desire, endlessly.
Conditional Tests and Conditional Branching
Often there are times when you want a
program to make a decision. For
example, suppose an accountant wishes
to write a program that will calculate
the amount of tax to be paid by a number
of persons. For those with incomes of
$10,000 or less , the tax is 17%. For
those with incomes of more than
$10,000, the tax is 20%. A flowchart for
the program might look like this: