


Section 4: Programming 275








STEP

INSTRUCTIONS

INPUT DATA/UNITS

KEYS

OUTPUT DATA/UNITS

1.

Load program




2.

Key in initial dnpmt

dpo


dpo





dp

3.

Key in inflation factor (monthly)

infl. fact


infl. fact.

4.

Key in initial savings

sav0


sav0





sav0

5.

Key in monthly savings

m sav.


m sav.

6.

Key in interest factor (monthly)

int. fact


int. fact

7.

To see dnpmt for month 1, 2, 3, etc.





repeatedly press



dp 1, 2, ...






8.

To see savings for month 1, 2, 3, etc.





repeatedly press



sav 1, 2, ...






9.

To see difference for month 1, press



sav, dpl


to get months 2, 3, etc. repeatedly press



diff 2, 3, ...






10.

To see month at which savings





overtake dnpmt, press



mo (diff+)






11.

To see difference at any month, enter

mo.


diff



The entire program requires 68 memory locations as shown on the preceding page.


To save the program, just pass a blank card through the calculator, switched to W/PRGM. Write the new
definitions of keys A, . . . , E on the magnetic card together with the program title. Then
fill out the HP65 User Instruction Form to remind you how to run the program at a later time. Finally,
if you wish, you can write your instructions on the HP65 Pocket Instructions Card. You may carry the
magnetic program card in it.


What we have presented is one possible way to write a program which gives us the required answers.
Doubtless you can think of other ways. You may wish to build your variable entry capability into the
program instead of storing them manually. You may wish to have the labels calculate differently than
we did. Perhaps you can find a way to show what month you are calculating for in labels A and B.
We urge you to try your own way.



