HP HP-67

124 Simple Programming
solve your own problems. If you have trouble with one of the prob-
lems, go back and review the explanations in the text, then tackle it
again.
So that you can apply your own creative flair to the problems, no
solutions are given for them. In programming, any solution that gives
the correct outputs is the right one—there is no one correct program
for any problem. In fact, when you have finished working through this
part, and learned all the capabilities of the HP-67, you may be able to
create programs that will solve many of the problems faster, or in
fewer steps, than we have shown in our illustrations.
Now let’s start programming!
What Is a Program?
A program is nothing more than a series of calculator keystrokes that
you would press to solve a problem manually. The calculator remem-
bers these keystrokes when you key them in, then executes them in
order at the press of a single key. If you want to execute the program
again and again, you have only to press the single key each time.
If you worked through Meet the HP-67 (pages 15-24), you learned
how to create, load, run, and record a simple program to solve for the
area of a sphere. Now look at a more complex program.
Loading a Prerecorded Program
First, set the calculator controls as follows:
ON-OFF switch orr[ Mo~ to ON.
W/PRGM-RUN switch wirrem Jl[[[run to RUN.
Now select the Moon Rocket Lander card from the Standard Pac
shipped with your HP-67. Insert side 1 of the card, face up, into the
lower slot provided on the right side of the calculator, and press it into
the slot until the reading mechanism picks it up and propels it out the
left slot. Let go of the card as soon as you feel it begin to be propelled
by the reading mechanism—don’t try to restrain its progress. If the
card does not read properly, the display will show [Error } and
you should then press any key on the keyboard to clear the error and
again pass side 1 of the card through the card reader slot. Then insert
the card in the upper slot so that the writing is visible in the window
above the keys marked @ & B 3