HP HP-67

132 Simple Programming
Clearing a Program
When you ran the magnetic card containing the Moon Rocket Lander
program through the card reader with the W/PRGM-RUN switch set to
RUN, the program was copied from the card into program memory in
the calculator. Before you can key in a program, you will first want to
clear, or erase, the Moon Rocket Lander program from the cal-
culator’s program memory. You can clear a program in any of three
ways.
To clear a program from the calculator, you can either:
1. Press £ with the W/PRGM-RUN switch
wercm [[MMRUN set to W/PRGM. This replaces whatever in-
structions are in program memory with instructions. In
W/PRGM mode, [} also specifies (FX] 2 display mode,
trigonometric mode, clears all flags, and restores the de-
fault functions to the top row keys. (A instruction encoun-
tered in a program stops the execution of that program. A flag is
a status indicator within a program. More about these later.) The
stack and storage register contents remain intact when [
is pressed.
2. Pass another magnetic card containing a program through the
card reader with the W/PRGM-RUN switch wrram [ RN
set the RUN. This replaces whatever instructions are contained
in the calculator’s program memory with the instructions for the
new program. (Reading a blank card does not alter the contents
of program memory, and the calculator displays
to indicate that the card has not been read.)
3. Turn the HP-67 OFF, then ON. This replaces whatever instruc-
tions are in program memory with instructions.
Now you are going to load your own program into the calculator from
the keyboard, so to first clear the HP-67 of the previous program:
Slide the W/PRGM-RUN switch wercm [[[IlllRUN to
W/PRGM.
Press [ to clear program memory. (This also sets the
calculator to step 000 of program memory.)