HP HP-28S - Interactive Programs; Asking for Input

27
Interactive Programs
Some programs require direction from the user-that is, from you
when you're running the program. When the user must supply values
for variables, a
program can ask for input. When the user must
choose among several alternatives, a program can ask for a choice.
This
chapter demonstrates how a program can ask for input or a
choice,
using the following commands from the PROGRAM CON-
TROL menu.
Command Description
HALT Suspend program execution.
s WAIT
Suspend program execution for s seconds.
KEY Return a key string if a key was pressed.
f s BEEP Sound a tone of frequency f for s seconds.
CLLCD
Clear the display.
n DISP Display an object in line n of the display.
CLMF Restore
the normal display when the program completes
execution.
Asking for Input
The following sequence creates a custom input menu for variables A,
B, and C sounds a tone to alert the user, and halts for input.
... -:: STO ABC ::- t'1HW 44~] ,1 BEEP HALT ...
234 27: Interactive Programs
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