Helwett Packard HP-55 User guide

HEWLETT-PACKARD
ElRR:SIS

How to Use This Handbook
This handbook is organized so that it can be used in either of
two ways:
= A logical arrangement of topics lets you read it straight
through if desired.
= Major topics are self-contained, wherever possible, so
that it is not necessary to read an entire section to extract
one idea.
Sections 1, 2, and 3 show you how to calculate with your HP-55;
section 4 (edged in blue ) describes the operation of the digital
timer and section 5 tells you how to program your HP-55.
If you are a beginner, you will appreciate the step-by-step
explanations in this handbook. But if you are already familiar
with Hewlett-Packard pocket calculators, you may find that the
supplementary Quick Reference Guide is all that you need.
Whenever you require additional information about a particular
operation, you can refer back to this handbook.
Before using the calculator you may need to
charge its battery pack as described in appendix A.
The calculator can then be operated while the bat-
tery is charging or, later, on battery power alone.

HEWLETT@PACKARD
EllRS))
Owner’s Handbook
February 1975
00055-90001 Rev. B 2/75
PRINTED IN U.S.A. © HEWLETT-PACKARD

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Figure 1. Keyboard Layout

Display
Mode Switch
——— OFF-ON Switch
xsY x=Y
——— Programming Keys:
Prefix Keys: i@ [@
inZmm fti=m gal=|
Metric Conversions: — ——— ———
Ibm=kg Ibf =N °Fz°C
1 1
Btu=J
—
——— Arithmetic Keys: |
——— Timer and Program Control Key:

Contents
Versatility Is Everything ............................ 7
Section 1: Getting Started
Power On ... 9
Keyboard ... ... . . . 9
Gold Operations .......... i 9
Blue Operations .............. ... . ... 9
Initial Display ... .. 10
Keying In and Entering Numbers ..................... 10
Simple Arithmetic ....... ... .. .. . 12
Arithmetic and the Stack .............. ... ... ... ..., 15
Left to Right Execution .......................... 18
Constant Arithmetic .......... ... ... ... ... ... 21
Manipulating Numbers in the Stack .................. 21
Rotating the Stack ........... . ... ... 22
Exchanging Xand Y ............ ... 23
Storing and Recalling Numbers ...................... 23
Storing Numbers ......... ... . 24
Recalling Numbers ... ... .. ... ... ... ... 24
Storage Register Arithmetic ...................... 25
Clearing Operations ............. ... ... ... 27
Clearing Storage Registers and the Stack ........ 27
Clearing Prefix Keys ......... .. ... . . 27
Section 2: Fundamental Operations
The Display Format .......... ... .. ... i, 29
Negative Numbers ................... ... ... ... ..... 31
Entering Exponents ........... ... .. 32
Powersof Ten ... ... ... ... ... . ... 32
Negative Exponents ................. ... ... .. 32
Pi 33
Last X . 33
To Avoid Reentering Numbers ................. .. 33
To Correct Input Errors ... o i 34
Basic Functions ........ ... .. .. 34
Reciprocal .......... .. . 34
Square and Square Root ................. ... .. .. 34
Percentage ........... ... 35

Summations ...
Accumulating Results ...........................
DeletingData ...................................
Sums of Products .................. .. ... .. ....
RCL =+
Section 3: Keyboard Calculations
Logarithms ... . .
Natural Logarithms . ..... .. ... ... ... ... ....
Common Logarithms ............................
Exponentials ........ ...
Roots ... ... .
Factorial ... ... ... .. . .
Angular Functions .......... ... ...
Angular Modes .............. ... . oo
Trigonometric Functions ........................
Angle Conversion ............ ... ... .. .. ..
Angular Mode Conversion .......................
Angle Arithmetic in Degrees, Minutes, and Seconds. .
Conversions ... ...
Coordinate Conversion ..........................
English/Metric Conversion .......................
Statistics ...
Mean ... ...
Linear Regression ...............................
Linear Estimate ...................... ... ... ....
Section 4: Using the Timer
Starting the Timer ........... ... ... ... .. ..........
Stopping the Timer ..................................
Changing the Display ................................
Taking Splits ......... ... .
Adding and Subtracting Times .......................
Converting Times ...
Section 5: Programming
What Is a Program?
Program Memory
42
42

Writing a Program ......... ... .. .. i 71
Setting the Program Pointer ..................... 72
Keying Ina Program ............................ 73
Endinga Program .......... ... ... ... .......... 74
Running the Program ............................... 75
Single Step and Back Step .......... ... 75
Changing or Correcting a Program ................... 76
Branching ....... .. ... ... 78
Simple Branching ........... ... ... ............ 78
Conditional Branching .......................... 80
Debugging Your Programs .......................... 82
Program Stops ............. 82
Single-Step Execution .................. ... ...... 83
Common Mistakes .......................... .. ... 83
Appendix A: General Information
ACCESSOIIeS ... i 85
Standard Accessories ............... .o 85
Optional ACcessories ............coeiiuuuennno.. 85
Battery Operation ........... ... ... ... ... ... ... 85
Recharging and AC Line Operation .................. 86
Battery Pack Replacement ........................... 87
Appendix B: Additional Operating Information
Automatic Stack Lift ................... 90
Calculating Range .......... ..o 91
Underflow ... 91
Overflow ... 91
Temperature Range ................ ... ... ... 91
Appendix C: Calculator Troubleshooting
Blank Display ... 92
Multiple Decimal Point Display ....................... 92
Blurring Display ........ooiiii i 92
Flashing Display ..., 92
Battery Failure ....... .. .. . 92
Warranty ... 93
Shipping Instructions ................. ... .. 93
Index .o 95

Versatility Is Everything
The HP-55 is an incredibly versatile calculator designed to pro-
vide in one compact, attractive package the functions and
features you need most. For example, take its precision digital
timer. Did you know that most electronic calculators possess
many of the ingredients necessary for a digital timer? The
HP-55, however, has added a very small quartz crystal to pro-
vide an accurate time base. The result is a precision digital timer
with a range of 100 hours.
Why not try the timer yourself now? Switch the calculator ON
and set the mode switch in the upper right hand corner to
TIMER. You should see 00.00.00 00 in the display. Then
you can start the timer by pressing [ (run/stop). While it is
running, read the list of features that follows.
1. The HP-55 is programmable to help you create on-the-
spot programs for faster, easier, and more accurate
solutions to your special problems.
2. The HP-55’s keystroke programming is simple and easy
to understand and includes both direct and conditional
branching.
3. To help you with programming, several editing features
allow you to review programs easily as you're writing
them.
4. The HP-55 also features more pre-programmed func-
tions than any other scientific pocket calculator in
the world.
5. Itprovides 20 addressable data storage locations to make
data manipulation easy regardless of the problem.
6. Like other Hewlett-Packard calculators, the HP-55
offers a four-register operational stack and reverse Polish
notation (RPN) to make your problem-solving easier.
7. It also provides statistics for mean, standard devi-
ation, and linear regression calculations.
8. And of course it has transcendental functions, such as
sines, cosines, logarithms, etc.; and polar/rectangular
coordinate conversions for handling vectors and com-
plex arithmetic.
9. Also, for your convenience, the HP-55 provides a variety
of metric/English conversions.
7

10. The precision digital timer, which you have running, is
combined with the ability to store times while the timer
is running and later recall them.
11. To increase your calculating power, two books of pro-
grams are also available:
= HP-55 Mathematics Programs
= HP-55 Statistics Programs
These books contain a representative collection of key
sequence routines for solving mathematics and statistics
problems in the most efficient manner.
Okay, now press again to stop the timer. Now let’s calcu-
late your reading speed. The list of features is about 230 words
long. To calculate your reading speed, set the switch in the
upper right hand corner of the calculator to RUN and press:
H=HM
Pl EExEE D R =
The answer is in words per minute. Try it again if you like!

Section 1
Getting Started
Power On
Your HP-55 calculator is shipped fully assembled and is ready
to calculate after making a few simple checks. If you have just
received your calculator, please be sure that you have all of the
standard accessories and that the calculator’s battery pack has
been charged. (Refer to appendix A.) If the battery pack is
already charged or if you plan to run the calculator from the
charger, here’s how to get started:
= Set the power switch to OFF.
= Set the mode switch to RUN.
= Set the power switch to ON.
You should now see displayed 0.00; if not, please refer to
appendix C.
The display flashes whenever an improper operation has been
attempted. You can stop the flashes by pressing any key.
Improper operations are listed on the inside back cover of
this handbook.
Keyboard
Figure 1, inside the cover foldout, illustrates the keyboard lay-
out. The blue and gold prefix keys are used to increase the
number of functions for each key.
Gold Operations
Press the gold [ prefix key before an operation written in gold
above the key or before a conversion in the direction of the
gold arrow.
Blue Operations
Press the blue @ prefix key before an operation written in blue
above the key or before a conversion in the direction of the
blue arrow.
Note: Gold and blue functions are shown in this hand-
. . —_ X
book as appearing above a key like this: -2, —@0m, e
9

Initial Display
When you first switch the calculator ON with the mode switch
set to RUN, the display shows 0.00. This represents the con-
tents of the display, or **X-register.”
Basically, numbers are stored and manipulated in the machine
in things called ‘‘registers.”” Each number, no matter how
simple (i.e., 0, 1, or 5) or how complex (i.e., 3.141592654,
—23.28362, or 2.87148907 x 10%7), occupies one entire register.
The displayed X-register, which is the only visible register, is
one of four registers inside the calculator that are positioned to
form the ‘‘operational stack.”” We label these registers X, Y, Z,
and T. They are “‘stacked’’ one on top of the other with the dis-
played X-register on the bottom. When the calculator is
switched ON, these four registers are cleared to 0.00.
Name Register
T (top) 0.00
7 0.00
Y 0.00
X 0.00 Always displayed
Keying In and Entering Numbers
Key in numbers from left to right and include the decimal point
if it is a part of the number. For example, 314.32 is keyed in by
pressing:
[ @ (2
Why not try it yourself now? If you make a mistake, clear the
entire number by pressing €LX (clear x); then key in the num-
ber correctly. Your stack registers now look like this:
Name Register
T 0.00
z 0.00
Y 0.00
X 314.32

In order to key in a second number, you must tell the calculator
that you’re finished with the first number. For example, if you
were to key in 567 right now, the number in the displayed X-
register would be 314.32567 and the calculator would still
not know if you were through. (It’s clever, but it can’t read
your mind.)
One way to tell the calculator you’re through with a number is
to press [ENTER4 .* Press ENTER4 to change the contents of the
registers
from this: to this:
T 0.00 T 0.00
7 0.00 Z 0.00
Y 0.00 Y 314.32
X |314.32 X |314.32
As youcan see, the number in the displayed X-register is copied
into Y. (The numbers in Y and Z have also been transferred to
Z and T, respectively, and the number in T has been lost. But
this will be more apparent when we have different numbers in
all four registers.)
Immediately after pressing ENTER4 , the X-register is prepared
for anew number. And that new number writes over the number
in X. For example, key in the number 543.28 and the contents of
the stack registers change
from this: to this:
T 0.00 T 0.00
z 0.00 Z 0.00
Y 314.32 Y 314.32
X | 314.32 X | 543.28
*A detailed discussion on number termination can be found in appendix B.

CLX also prepares the displayed X-register for a new number by
replacing any number in the display with zero. Any new number
then writes over the zero in X. For example, press cLx now to
change the stack
from this: to this:
T 0.00 T 0.00
4 0.00 zZ 0.00
Y |314.32 Y 314.32
X | 543.28 X 0.00
And then key in 689.4 to change the stack
from this: to this:
T 0.00 T 0.00
Z 0.00 Z 0.00
Y 314.32 Y 314.32
X 0.00 X 689.4
Notice that numbers in the stack do not move when a new
number is keyed in immediately after pressing ENTER# or CLX .
Simple Arithmetic
Hewlett-Packard calculators do arithmetic by positioning the
numbers in the stack the same way you would on paper. For
instance, if you wanted to add 34 and 21 you would write 34 on a
piece of paper and then write 21 underneath it like this:
34
21
and then you’d add like this:
34
+ 21
55

Numbers are positioned the same way in the HP-55. Here’s
how it is done (Clear the previous number entry first by
pressing CLX .)
Press Display
34 34 is keyed into X.
ENTER4 34.00 34 is copied into Y.
21 21 writes over the 34 in X.
Now 34 and 21 are sitting vertically in the stack as shown below,
so we can add.
T 0.00
Z 0.00
Y | 34.00
X 21.
Press Display
: The answer.
The simple old-fashioned math notation explains how to use
your calculator. Both numbers are always positioned in the
stack first and then the operation is executed when the key is
pressed. There are no exceptions to this rule.

Subtraction, multiplication, and division work the same way.
In each case, the data must be in the proper position before the
operation can be performed.
34
To subtract 21 from 34 721>:
Press Display
34 34 34 is keyed into X.
ENTER4 34.00 34 is copied into Y.
21 21. 21 writes over the 34 in X.
= 13.00 The answer.
TN
34
To multiply 34 by 21 ><21>:
Press Display
34 34 is keyed into X.
ENTER4 34 is copied into Y.
21 21 writes over the 34 in X.
x The answer.
34
To divide 34 by 21 <2l>:
Press Display
34 34 is keyed into X.
ENTER#4 34 is copied into Y.
21 21 writes over the 34 in X.
+ The answer.

Arithmetic and the Stack
You’ve already learned how to enter numbers into the calcu-
lator and perform calculations with them. In each case you first
needed to position the numbers in the stack manually using the
ENTER+ key. However, the stack also performs many move-
ments automatically. It’s these automatic movements that give
it tremendous computing efficiency and ease of use. The stack
automatically “‘lifts”’ every calculated number in the stack
when a new numberis keyed in because it knows when it com-
pletes a calculation that any digits you key in are a part of a new
number. For example, calculate 16 + 30 + 11 + 17 = ?
Note: For the sake of simplicity in the following ex-
amples, we are going to assume that the stack contains
no data from previous examples.
Press Stack Contents Comments
0.00
0.00 16 is keyed into the displayed
0.00 X-register
16.
X<
N A
0.00
0.00
16.00
16.00
ENTER4
16 is copied into Y.
X
<N
0.00
0.00
16.00
30.
30 30 writes over the 16 in X.
X<
NH
0.00
0.00 16 and 30 are added together.
0.00 The answer, 46 is displayed.
46.00
X< NH

Press Stack Contents Comments
0.00 .
T 0.00 11 is keyed into the displayed
11 Z : X-register. The 46 in the stack
Y 46.00 . . .
is automatically raised.
X 11.
T 0.00
Z 0.00 46 and 11 are added together.
* Y 0.00 The answer, 57, is displayed.
X 57.00
T 0.00 . . .
17is keyed into the X-register.
Z 0.00 . .
17 57 is automatically entered
Y 57.00 .
into Y.
X |7
T 0.00
Z 0.00 57 and 17 are added together
* Y 0.00 for the final answer.
X 74.00
After any calculation or number manipulation, the stack auto-
matically lifts when a new number is keyed in. (Refer to Auto-
matic Stack Lift in appendix B.) Because operations are performed
when they are pressed, the length of this problem is unlimited
until the answers exceed the range of the calculator (up to 101%!).
In addition to the automatic stack lift after a calculation, the
stack automatically drops during calculations involving both
X- and Y-registers. It happened in the above example, but let’s
do the problem differently to see this feature more clearly.