88 Section 8: Programming Basics
Example: Run the program created above to calculate the net cost of a
typewriter listing for $625 and an executive chair listing for $159.
That’s all there is to creating and running simple programs! But if you want to
use programs frequently, you’ll want to know more about programming – such
as how to check what keystrokes are stored in program memory, how many
keystrokes can be stored in program memory, how to correct or otherwise
modify programs, how to skip keystrokes when running a program, and so on.
Before you can understand these aspects of programming, we need to briefly
discuss how keystrokes are treated by the calculator when they are stored in
Program mode and when they are executed in Run mode.
Program Memory
Keystrokes entered into the calculator in Program mode are stored in program
memory. Each digit, decimal point, or function key is called an instruction and is
stored in one line of program memory – usually referred to simply as a program
line. Keystroke sequences beginning with the f, g, ?, :, and i
prefix keys are considered to comprise a complete instruction and are stored in
only one program line.
When a program is run, each instruction in program memory is executed – that
is, the keystroke in that program line is performed, just as if you were pressing
the key manually – beginning with the current line in program memory and
proceeding sequentially with the higher-numbered program lines.
Whenever the calculator is in Program mode (that is, whenever the PRGM status
indicator in the display is lit), the display shows information about the program
line to which the calculator is currently set. At the left of the display is the
number of the program line within program memory. The remaining digits in the
display comprise a code that indicates what instruction has been stored in that
program line. No code is shown for program line 000, since no regular
instruction is stored there.
Keystrokes (RPN mode) Display
fs
155.00
Sets calculator to Run mode.
Display shows number previously
calculated.
f]
155.00
Sets RPN mode.
625
625.
Keys in price of typewriter.
t
473.75
Net cost of typewriter.
159
159.
Keys in list price of chair.
t
124.25
Net cost of chair.
