HP 35s User Manual page 5

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HP 35s Writing a Simple Program
the new label's name at the beginning of each line. Figure 7 shows an example of this; if both program A and program B
were typed, then after the RTN in program B, the first line of program A is displayed on the calculator screen.
Each label can be used only one time, and the HP 35s treats the lines from one label until the next label as a separate
program. It is also possible to have a program with no label, from the "PRGM TOP" until the first label.
To list the programs in the HP 35s, press the keys ¹u to get the "Memory" menu, and then 2 to get a display
of programs. If the algebraic version of the circle program has been entered then the calculator screen will look like
Figure 12. If only program A was typed, the screen will be as in Figure 13.
This means that the program with label B is the first program in memory, and that it is 25 bytes long. A byte is a piece of
calculator memory made up of 8 bits, and a bit is the smallest piece of memory, a single "0" or "1". The HP 35s has more
than 29,000 bytes of memory available to hold programs and equations entered by the user. Given this much memory, a
long program could have up to 999 program lines, and that is why program line numbers are 3 digits long. The up and
down arrows at the right of the screen mean that there are more programs in the calculator – information about each
program in turn is displayed if the up or down arrow keys are pressed. If both the programs A and B have been entered,
press Ø to see information about program A.
Another tool to help in writing programs is the program checksum. To see the checksum for program A, press
¹Î. While the Î key is held down, the calculator will show:
CK=DAF1means that the checksum for program A is the hexadecimal number DAF1. (The checksum for program B is
AD0A.) If the program was not typed correctly, then the checksum will be different. Press the key labeled Å at the
bottom left of the keyboard to cancel the display of information about programs.
The checksum has several purposes:
•
If a program is correctly copied to the HP 35s from a web page or a book – the HP 35s manual has many useful
example programs – then the checksum on the HP 35s will be the same as the checksum given with the
program. If the checksum is not the same, a mistake was made and the program should be checked and
corrected before it is used.
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Figure 11
Figure 12
Figure 13
Figure 14
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