HP 15c - Manual (Page 70)

70 Section 6: Programming Basics
This is the method used above, where h was placed in the X-register
before running the program. No v instruction is necessary
because program execution (here: ´A)
both terminates digit
entry and enables the stack lift. The above program then multiplied
the contents of the X-register (h) by 2.
The presence of the stack even makes it possible to load more than
one variable prior to running a program. Keeping in mind how the
stack moves with subsequent calculations and how the stack can be
manipulated (as with ®), it is possible to write a program to use
variables which have been keyed into the X-, Y-, Z-, and T-registers.
2. Direct entry. Enter the data as needed as the program runs. Write a
¦ (run/stop) instruction into the program where needed so the
program will stop execution. Enter your data, then press ¦
to
restart the program.
Do not key variable data into the program itself. Any values that will vary
should be entered anew with each program execution.
Program Memory
At power-up (Continuous Memory reset), the HP-15C offers 322 bytes of
program memory and 21 storage registers. Most program steps
(instructions) use one byte, but some use two. The distribution of memory
capacity can be altered, as explained in appendix C. The maximum
attainable program memory is 448 bytes (with the permanent storage
registers—R
I
, R
0
, and R
1
—
remaining); maximum number of storage
registers is 67 (with no program memory).
Example. Mother's Kitchen, a canning
company, wants to package a ready-to-
eat spaghetti mix containing three
different cylindrical cans: one of
spaghetti sauce, one of grated cheese,
and one of meatballs. Mother's needs to
calculate the base areas, total surface
areas, and volumes of the three different
cans. It would also like to know, per
package, the total base area, surface
area, and volume.