HP HP-11C User guide

HEWLETT-PACKARD
Getting Started (page 165)
Memory Stack, LAST X, and Data Storage (page 26)
)
Numeric Functions page 42) ) =
Display
Control
(page
67)
)
;
)| OWNER’S HANDBOOK AND
Programming Basics (page 74)
PROBLEM-SOLVING GUIDE
—
Program Editing (page 96)
Program Decisions and Control (page 110) )
Subroutines (page 119)
The Index Register (page 127) )
Applications Programs (page 140) )
Programming Techniques (page 206) )
i @ HEWLETT
PACKARD
Portable Computer Division
1000 N.E. Circle Bivd., Corvallis, OR 97330, U.S.A.
00011-90001 Rev. G English Printed in Canada 11/85
i i a i a

Notice
Hewlett-Packard Company makes no express or implied
warranty with regard to the keystroke procedures and
Program material offered or their merchantability or their
fitness for any parti @ keystroke proced!
basis, and the entire risk as to their quality and performance is
with the user. Should the keystroke procedures or program
material prove defective, the user (and not Hewlett-Packard
Company nor any other party) shall bear the entire cost of all
necessary correction and all incidental or consequential
damages. Hewlett-Packard Company shall not be lia! for
any incidental or consequential damages in connection with
or arising out of the furnishing, use, or performance of the
keystroke procedures or program material.
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ad
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HEWLETT
PACKARD
HP-11C
Owner’s Handbook
and
Problem Solving Guide
November 1985
00011-90001 Rev. G
Printed in Canada 11/85
© Hewlett-Packard Company 1982

Introduction
Congratulations! Your selection of an HP-11C calculator with
Continuous Memory demonstrates your interest in quality,
capability, and ease of use. This handbook describes the
calculator’s many features and can help you to quickly learn how
to use the features you are not already familiar with.
Fundamentals, Programming, Applications Programs. Your
HP-11C handbook is divided into three main parts. Parts I and II
cover the use of keyboard and programming features you may be
familiar with if you have used other HP programmable calculators.
Part III provides you with a variety of applications programs, plus
some additional information on fundamental programming
practices. However, before you begin reading in any of the three
main parts, we suggest that you gain some experience using your
HP-11C by working through the introductory material entitled
Your HP-11C, A Problem Solver, on page 9.
Programming Sections in Brief. At or near the beginning of
each section in part II (sections five through nine) is a brief
discussion of the operating characteristics covered in that section.
This information may be all you need to read in the section if you
already know how to create, run, and edit programs on another HP
calculator. If you are new to HP calculators, you’ll want to also
read the remaining material in each section for a more tutorial
discussion and/or examples that highlight selected topics.
Additional Applications. Also available from many authorized
Hewlett-Packard dealers is the HP-11C Solutions Handbook. This
accessory handbook contains a comprehensive collection of
HP-11C programs covering applications in mathematics, statis-
tics, electrical engineering, chemistry, business, and games.
ue
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pes
Contents
Introduction
The
HP-11C
Keyboard
and
Continuous
Memory
Your
HP-11C:
A
Problem
Solver
-
Manual Solutions .........+-05+ss 6 1
Programmed Solutions .........0.sesseeee reece eee Pie |
Part
I:
HP-11C
Fundamentals
.....
eae
Gaye
Reise
eiet
15
Section
1;
Getting
Started
Power
On
and
Off
...
Display
Radix
Mark
and
Digit
Separator
Annunciators
.,....
Negative
Numbers
..
Display
Clearing:
(CLx
Running
......eeeee
vers
Overflow
and
Underflow
...
Error
Messages
.........
Low
Battery
Indicator
.
Memory
........e0.000s
Continuous
Memory
Resetting
Memory
..
Keyboard
Operation
...
Primary
and
Alternate
Functions
Clearing
Prefixes
.........
ra
5
|
One-Number
Functions
.
Two-Number
Functions
...
Section 2: The Automatic Memory Stack, LAST X,
and Data Storage
The Automatic Memory Stack and Stack Manipulation . . 26
Stack Manipulation Functions ....... 27
Calculator Functions and the Stack .. 29
Two-Number Functions . . 29
Chain Calculations .. . 31
LASTX oo... eee eee 32
Constant Arithmetic 34

4 Contents
Storage
Register
Operations
.................,
37
Storing
Numbers
..
37
Recalling
Numbers
.
38
Storage
and
Recall
Exercises
.
38
Clearing
Data
Storage
Registers
..
38
Storage
Register
Arithmetic
...
.
39
Storage
Register
Arithmetic
Exercises
40
Problams
5
24)ci50
ee
akin
get
sea
e
oases
40
. 42
. 42
Number
Alteration
Functions
.
-
42
One-Number
Functions
..
-
43
General
Functions
...
-
43
Trigonometric
Operations
..
-
45
Time
and
Angie
Conversions
-
46
Degrees/Radians
Conversions
.
47
Logarithmic
Functions
.
-
48
Hyperbolic
Functions
..
.
48
Two-Number
Functions
. »
49
Exponential
..
.
49
Percentages
..
.
49
Polar-Rectangular
Coordinate
Conversions
.
51
Probability
.......
52
Statistics
Functions
.
54
Random
Number
Generator
.
54
Accumulating
Statistics
....
55
Correcting
Statistics
Accumulations
.
58
Mean ......,.......
Standard Deviation .
Linear Regression .........
Linear Estimation and Correlation Coefficient ..
Section 4: Display Control
Display Mode Control
Fixed Decimal! Display
Scientific Notation Display .
Engineering Notation Display
Keying In Exponents ......
Rounding at the Tenth Digit
ea a a
wwe
Contents 5
Part H: HP-11C Programming
Section 5: Programming Basics
Whatls a Program? ...
Why Write Programs? .
Program Control ......
Automatic Memory Reallocation
Keycodes and Line Numbers
Abbreviated Key Sequences
Program Control Functions .
User Mode .....c.ccccrveneee
Program Memory .....
Interpreting Keycodes .
Programming Operations
Beginning and Ending a Program
The Complete Program .......
Loading a Program ..
Running a Program .
User Mode Operation .
Program Stops and Pauses
Planned Stops During Program Execution .
Pausing During Program Execution .
Unexpected Program Stops .
Labels ..
Problems .
Section
6:
Program
Editing
..
96
Finding
Program
Errors
..
96
Editing
Functions
...
97
Editing
Example
..
. 98
Single-Step Execution of a Program 99
Using [SST] and [BST] in Program Mode 100
Modifying a Program
Problems
Section 7: Program Decisions and Control ..
Program Conditional Tests
Flags’ cvccsecsaces
Program Control ..
GoTo
Branching and Looping .
Using Flags ..

6 Contents
Section 8: Subroutines ...
Go To Subroutine ..
Subroutine Limits ..
Subroutine Usage ...
119
119
. 120
121
. 127
127
130
132
134
135
136
136
. 137
Section 9: The Index Register .
Direct Index Register Functions .
Indirect Index Register Functions
Loop Control Using [ISG] . .
Direct R, Operations ..
Indirect R, Operations ..
Indirect Program Control ...
Indirect Label Branches and Subroutines .
Indirect Line Number Branches and Subroutines ...
. 139
140
140
149
154
Part III: Programmed Problem Solving ..
Section 10: Applications Programs
MatrixAlgebra ............... 0. cere
Systems of Linear Equations With Three Unknowns
Newton's Method (Solution to f(x) =O) ...
Numerical Integration by Discrete Points .
Curve Fitting
Triangle Solutions
t Statistics
Chi-Square Evaluation ...
Finance: Annuities and Compound Amounts .
Submarine Hunt
. 206
Section 11: Programming Techniques . _
Structure ..............e0 206
The Problem Statement +. 206
. 206
The Algorithm
Flowcharts . 208
Subroutines .. 210
(isG} With (RCL. 211
Datalnput ... 212
Looping .. 214
215
217
217
218
. 218
Flags ..
Random Numbers
User-Definable Keys
Storing Data ...
Selecting Different Routines .
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Contents 7
Appendix A: Error Conditions
Appendix B: Stack Lift and LAST X
Digit Entry Termination ..
Stack LA vacscceesees
Disabling Operations
Enabling Operations ..
Neutral Operations ...
LASTX .
Appendix How Automatic Memory
Reallocation Operates
Converting Storage Reyisters to Program Memory
Converting Program Memory to Storage Registers
Using [MEM] ...... 0.0 cece cece cence ere etn ee enee
Appendix D: Battery, Warranty, and
Service
Information
.
Batteries ............-...- . 230
Low Power Indication . 231
Installing New Batteries ... 231
Verifying Proper Operation (Self Tests) . 234
Limited One-Year Warranty .. 236
What is Not Covered 236
Warranty for Consumer Transactions in the
United Kingdom
Obligation to Make Changes .
Warranty Information ...
Obtaining Repair Service in Europe
International Service Information .
Service Repair Charge ...
Service Warranty
Shipping Instructions ...
Further Information .
When You Need Help
Temperature Specifications .......
Potential for Radio and Television
Interference (for U.S.A. Only) ....- 242
Programming
Techniques
Index
.
243
Function
Key
Index
.......
245
Programming
Key
Index
249
Subject
Index
........--...-
.
251

The HP-11C Keyboard and
Continuous Memory
=
=
AUTOMATIC
(Bq
Memory
stack
TTT
ITT
pg
ITTT
TTT
TT
Meee
a
a
a
a
x»
Displayed
LASTX
PROGRAM MEMORY
STORAGE REGISTERS
Permanent Shared Permanent Shared
[ooo- |{oea- JR,L_ro[ JR»
seis fone I :
[oa |lose- |
|
rol]
[os1- _|[zor-__| — tg
The
basic
program
memory-storage
register
allocation
is
63
lines
of
programming
and
20
data
storage
registers,
plus
the
Index
register
(Rj).
The
calculator
automatically
converts
one
data
storage
register
into
seven
lines
of
program memory,
one
register
at
a
time,
as
you
need
them.
Conversion
begins
with
R
g and
ends
with
Ro.
eo @y
UU
Your HP-11C:
A Problem Solver
Your HP-11C Programmable Scientific Calculator is a powerful
problem solver you can carry with you almost anywhere to handle
problems ranging from the simple to the complex, and to remember
important data. The HP-11C is so easy to program and use that it
requires no prior programming experience or knowledge of
programming languages.
The HP-11C helps you to conserve power by automatically shutting
itself off if it is left on and inactive for more than 8 to 17 minutes.
But don’t worry about losing data—any information you have
keyed into your HP-11C is saved by Continuous Memory.
We're different! Your Hewlett-Packard calculator uses a unique
operating logic, represented by the key, that differs from the
logic in most other calculators. The power in HP calculator logic
becomes obvious through use. Later we will cover the details of
and your HP-11C’s logic, but right now let’s get acquainted
with [ENTER] by seeing how easy it is to perform calculations with
your HP-11C,
Answers appear immediately after you press a numerical function
key. For example, let’s look at the arithmetic functions. The (4) key
adds the last entry to whatever is already in the machine, and the
=] key subtracts the last entry; the [x] key multiplies what’s in the
machine by the last entry, and the [=] key divides by the last entry.
First we have to get the numbers into the machine. To do this, key
in the first number, press [ENTER] to separate the first number from
the second, then key in the second number and press (+], [=], [x], or
9

10 Your HP-11C: A Problem Solver
To get the feel of your new calculator
turn it on by pressing the (ON) key" If
any nonzero digits appear, press [+]
to clear the display to 0.0000. If four
zeroes are not displayed to the right
of the decimal point, press [f][FIX]4 so
your display will match those in the
following problems. (All displays
illustrated in this handbook are set to
the [FIX] 4 display setting unless
otherwise specified.)
0.0000
Note: An asterisk (*) flashing in the lower-left corner of the
display when the calculator is turned on signifies that the
available battery power is nearly exhausted. To install new
batteries, refer to appendix D.
Manual Solutions
It is not necessary to clear the calculator between problems. But if
you make a digit entry mistake, press [) and key in the correct
digit.
To Solve Keystrokes Display
9 (ENTER]6 (+ 15.0000
9 (ENTER]6 (— 3.0000
9 [ENTER] 6 [x] 54.0000
9 [ENTER] 6 [+] 1.5000
Notice that in the four examples:
e Both numbers are in the calculator before you press (+), ©), Gd,
e [ENTER]is used only to separate two numbers that are keyed in
one after the other.
e Pressing a numerical function key, in this case G), ©), (x), or
©), causes the function to execute immediately and the result
to be displayed.
* Note that the [ON] key is lower than the other keys to help prevent its being pressed
inadvertantly.
~~ —~wvrrewrew
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wee Oe ee
Your HP-11C: A Problem Solver 14
To see the close relationship between manual and programmed
problem solving, let’s first calculate the solution to a problem
manually, that is, from the keyboard. Then we'll use a program to
calculate the solution to the same problem and others like it.
Most conventional home water heaters are cylindrical in shape.
You can easily calculate the heat loss from such a tank using the
formula g =h X A X T, where:
qis the heat loss from the water heater (Btu per hour).
his the heat-transfer coefficient.
Ais the total surface area of the cylinder.
T is the temperature difference between the cylinder and the
surrounding air.
Example: Assume you have a 52-
gallon cylindrical water heater and
you wish to determine how much
energy is being lost because of poor
insulation. In initial measurements,
you found an average temperature
difference between the heater surface
and surrounding air of 15 degrees
Fahrenheit. The surface area of the
tank is 30 square feet and the heat
transfer coefficient is approximately
0.47. To calculate the heat loss of the
water heater, simply press the follow-
ing keys in order.
Keystrokes Display
15 15.0000 Input temperature
30 30 difference (7) and area of
water heater (A).
J 450.0000 Calculates A x 7.
47 0.47 Heat-transfer coefficient
(A).
x 211,5000 Heat loss in Btu per hour
(hX(AT)).
ic] 0.0000 Clears display.

12 Your HP-11C: A Problem Solver
Programmed Solutions
The
heat
loss
for
the
water
heater
in
the
preceding
example
was
calculated
for
a 15-degree
temperature
difference.
But
suppose
you
want
to
calculate
the heat
loss
for
several
temperature
differences?
You
could
perform
each
heat
loss
calculation
manually.
However,
an
easier
and
faster
method
is
to
write
a
program
that
will
calculate
the heat
loss
for
any
temperature
difference.
Writing the Program. The program is the same series of
keystrokes you executed to solve the problem manually. Two
additional instructions, a label and a return, are used to define the
beginning and end of the program.
Loading
the
Program.
To
load
the
instructions
of
the
program
into
the
HP-11C
press
the
following
keys
in
order.
The
calculator
records
(remembers)
the
instructions
as
you
key
them
in.
(The
display
gives
you
information
you
will
find
useful
later,
but
which
you
can
ignore
for
now.)
Keystrokes Display
MPa o00- Places HP-11C in
Program mode. (Program
annunciator appears.)
f}CLEAR [PRGM. 000- Clears program memory.
#)(CBL)[A)
001-42,21,11
Label
“A”
defines
the
beginning of the program.
3 002- 3
to) 003- °
x
004-
20
§
The
same
keys
you
|
005-
48
>
pressed
to
solve
the
4
006-
4{
problem
manually.
7 007- 7
& 008- 20,
(a
)(RTN
009-
4332
“Return”
defines
the
end
of the program.
(a) [PR 0.0000 Places HP-11C in Run
mode. (Program
annunciator is cleared.)
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Your HP-11C: A Problem Solver 13/14
Running the Program. Press the following keys to run the
program.
Keystrokes Display
16 15 The first temperature
difference.
fA 211.6000 The Btu heat loss you
calculated earlier by
hand.
18 (fA 253.8000 The Btu heat loss for a
new temperature
difference.
With the program you have loaded,
you can now quickly calculate the
Btu heat loss for many temperature
differences. Simply key in the desired
difference and press [f] (A). For
example, complete the table at the
right.
The answers you should see are
141.0000, 169.2000, 197.4000,
225.6000, 253.8000, and 282.0000.
Programming is that easy! The calculator remembers a series of
keystrokes and then executes them whenever you wish. Now that
you have had some experience in using your HP-11C, let’s take a
look at some of the calculator’s important operating details.

Part I
HP-11C
Fundamentals
a
a
ee
ee
ee

Section 1
Getting Started
Power On and Off
The key turns the HP-11C on and off. And, to conserve power,
the HP-11C automatically turns itself off (time-out) after 8 to 17
minutes of inactivity.
Display
Radix Mark and Digit Separator
A radix mark is the divider between
the integer and fractional portions of
a number. A digit separator dis-
tinguishes the groups of digits in a
large number. In some countries the
radix is a decimal point and the digit
separator is a comma, while in other
countries, the reverse is true. To
change the radix/digit separator
convention on your HP-11C, turn off the calculator, then hold down
the [-] key, turn the calculator back on, and release the [] key
(Q)/ (on).
7 12,345,678.91
(oN
™\12.345.678,91
Radix Mark/Digit
Separator Exchange
Annunciators
Your HP-11C’s display contains six annunciators that tell you the
status of the calculator during certain operations. The annunci-
ators are described, with the operations they refer to, in the
appropriate sections of this handbook.
* USER fg GRAD — PRGM
Display Annunciator Set
16
a
Section 1; Getting Started 17
Negative Numbers
To make a displayed number negative—either one that has just
been keyed in or one that has resulted from a calculation— simply
press [CHS] (change sign). When the display shows a negative
number—that is, the number is preceded by a minus sign—
pressing
[CHS]
removes
the
minus
sign
from
the
display,
making
the number positive.
Display Clearing: [CLxJand [+
The
HP-11C
has
two
types
of
display
clearing
operations,
[CLx]
(clear
X)
and
[#]
(back
arrow).
When
pressed
in Run
mode,
[9
}[CLx]
clears
any
displayed
numbers
to
zero.
When
pressed
in
Program
mode,
v]is
stored
in
the
calculator
as
a
program
instruction.
)
is a
nonprogrammable
function
that
enables
you
to
clear
the
display
in either
Program
or
Run
mode,
as
follows:
1. In Run mode:
A. Pressing [€] after executing almost any function clears
all digits in the display to zero.* (Executing almost any
HP-11C function terminates digit entry—that is, tells
the calculator the number in the display is complete—
and causes (€] to act on the complete number.)
Keystrokes Display
12345 12,345
J] 111.1081
cS 0.0000 Pressing ()after
executing a function
clears all digits in the
display to zero.
* Unseen trailing digits of the number in the display may be held internally and will also
be cleared.

18 Section 1: Getting Started
B. After keying in a new number, if you press [€] before
executing a function (that is, before terminating digit
entry) the last digit you keyed in is deleted. After you
delete one or more digits, you can, if you want, key in
new digits to replace them.
Keystrokes Display
12345 12,345
(+) 1,234 When digit entry has not
[+] 123 been terminated, (#]acts
9 1,239 on each digit separately.
2. In Program mode, pressing (©) deletes the entire program
instruction currently in the display.
Running
While a program is running, or
during execution of [Py.x] (permuta-
tion) or (Cy,x] (combination), running
flashes in the display.
funning
Overflow and Underflow
Overflow. When the result of a
calculation in the displayed X-
register is a number with a magni-
tude greater than 9.999999999 x 10%,
all 9’s are displayed with the appro-
priate sign. When overflow occurs in
a running program, execution halts
and the overflow display appears.
9.999999 99
Overflow Display
Underflow. If the result of a calculation is a number with a
magnitude less than 1.000000000 x 10-%9, zero will be substituted
for that number. Underflow will not halt the execution of a running
program.
~~ iw ™
Y~wyew
Section 1: Getting Started 19
Error Messages
If
you
attempt
a
calculation
using
an
improper
parameter,
such
as
attempting
to
find
the
square
root
of
a
negative
number,
an
error
message
will
appear
in
the
display.
Keystrokes Display
4 (CHS -4
yx) ErrorO
[e}
-4.0000
For
a
complete
listing
of
error
messages
and
their
causes,
refer
to
appendix
A,
Error
Conditions.
A
summary
of
error
messages
is
printed
on
the
calculator’s
back
label.
To
clear
any
error
message,
press
(#]{or
any
other
key),
then
resume
normal
calculator
operation.
Low Battery Indicator
Whenever a flashing asterisk, which
indicates
low
power,
appears
in
the
;
lower
left-hand
side
of
the
display,
2
refer
to
Installing
New
Batteries,
page 231.
0.0000
Memory
Continuous Memory
The
Continuous
Memory
feature
in
your
HP-11C
maintains
the
following
even
when
the
calculator
is
turned
off:
¢ All numeric data stored in the calculator.
© All programs stored in the calculator.
e Display mode and setting.
e Flag settings.
©
Position
of
the
calculator
in
program
memory.
e
Any
pending
subroutine
returns.
© Trig mode (Degree, Radian, or Grad).

20 Section 1: Getting Started
When the HP-11C is turned on, it always “wakes up” in Run mode
(PRGM annunciator cleared), even if it was in Program mode
(PRGM annunciator displayed) when last turned off.
Continuous Memory is preserved for a short time when the
batteries are removed, allowing you to replace a set of low batteries
without losing any data or programs you want preserved in the
calculator.
Resetting Memory
If at any time you want to reset (entirely clear) the HP-11C’s
Continuous Memory, do the following:
Turn the HP-11C off.
Press and hold the [ON] key. ON
Press and hold the E)key. :
Release the key and Resetting
then release the ()key. Continuous Memory
Es Se BO ES
When you perform the memory reset
operation the error message shown to Pre
. H . ror
the right is displayed. Press [#] (or
any other key) to clear the message.
Note: Continuous Memory can be inadvertently reset if the
calculator is dropped or otherwise traumatized, or if power is
interrupted.
Keyboard Operation
Primary and Alternate Functions
Most keys on your HP-11C perform one primary and two alternate
functions. The primary function of any key is indicated by the
character on the horizontal face of the key. The two alternate
functions are indicated by the characters above and on the slanted
face of the key.
~we~
Section 1: Getting Started 21
© To select the alternate function
printed in gold above the key,
first press the gold prefix key [1),
then press the function key; for
example: [f)[z}.
¢ To select the primary function
on the face of the key, press only
that key; for example: (CHS).
¢ To select the alternate function
printed in blue on the slanted
face of the key, first press the
blue prefix key [9], then press
the function key; for example:
9 }[ABS}.
Notice that when you press the [f] or
(@] prefix keys, the f or g annunciator
appears and remains in the display
until a function key is pressed to
complete the sequence.
0.0000
Clearing Prefixes
If
you
make
a
mistake
while
keying
in
a
prefix
for
a
function,
press
7]CLEAR
[PREFIX]
to
cancel
the error.
(CLEAR
[PREFIX]
also
cancels
the
[STO],
[RCL],
[GTO],
(GSB),
[HYP],
and
[HyP"}
keys.)
Since
the
PREFIX]
key
is
also
used
to
display
the
mantissa
of
a
displayed
number,
all
ten
digits
of
the
number
in
the
display
will
appear
for
a
moment
after
[PREFIX]is
pressed
(in
Run
mode
only).
One-Number Functions
A one-number function is any numerical function that performs an
operation using only one number. To use any one-number function:
1. Key inthe number (if it is not already in the display).
2. Press the function key(s).
Keystrokes Display
45 45
9 }{LOG 1.6532

22
Section
1:
Getting
Started
Two-Number
Functions
A
two-number
function
must
have
two
numbers
present
in
the
calculator
before
executing
the
function.
(4],
(-], [x],
and
(¢)
are
examples
of
two-number
functions.
The
(ENTER)
Key.
If
one
of
the
numbers
you
need
for
a
two-number
function
is
already
in
the
calculator
as
the
result
of
a
previous
function,
you
do
not
need
to
use
the
[ENTER]
key.
However,
when
you
must
key
in
two
numbers
before
performing
a
function,
use
the
ENTER]
key
to
separate
the
two
numbers.
To
place
two
numbers
into
the
calculator
and
perform
a
two-
number
function
such
as
2
+
3:
1. Key in the first number.
2.
Press
[ENTER|to
separate
the
first
number
from
the
second.
3. Key in the second number.
4. Press the function key(s).
Keystrokes Display
2 2
ENTER 2.0000
3 3
# 0.6667
Order
of
Entry.
As
you
know
from
basic
arithmetic,
reversing
the
order
of
the
numbers
in
addition
and
multiplication
examples
will
not
affect
the
answer.
But
for
subtraction
or
division,
the
number
you
are
subtracting
or
dividing
by
is
always
the
second
number
keyed
in.
To
perform
Keystrokes
Display
10-3
10
[ENTER]
3
E
7.0000
3-10
3
(ENTER]1
~7.0000
10+3
10
[ENTER]
3
[=
3.3333
3+10
3
(ENTER)
10
(+
0.3000
Section 1: Getting Started 23
When working with your HP-11C’s other two-number functions
(such as [*]), remember that the number designated by x on the key
is
always
the
last
number
to
be
keyed
in.
For
example,
to
calculate
the value of 2 raised to the power of three (2°), key in 2, press
ENTER], key in the exponent, 3, then press [)"].
Keystrokes Display
2 2.0000
3 3 3is the x-value.
Co) 8.0000 2(y) raised to the third (x)
power.
Now try these problems. Notice that you have to press to
separate numbers only when they are being keyed in one
immediately after the other. A previously calculated result
(intermediate result) will be automatically separated from a new
number you key in.
To solve (2 + 4) +8:
Keystrokes Display
2 (ENTER 2.0000
4 4
G8 6.0000 (2+ 4)
8 8
+ 0.7500 (2+4)+8
To solve (9 +17 —4 + 23) +4:
Keystrokes Display
9 [ENTER 9.0000
17 26.0000 (9 +17)
4) 22.0000 (9+17—4)
23 [+ 45.0000 (9+17—4 + 23)
4: 11.2500 (94+17—4 + 23)+4
Even more complicated problems are solved in the same simple
manner—using automatic storage of intermediate results.

24 Section 1: Getting Started
Example: Solve (6 + 7) X(9 — 3).
First solve for the intermediate result of (6+7):
Keystrokes Display
6 6
6.0000
7 7
13.0000 (6+7)
Now
perform
(9
—
3).
Since
another
pair
of
numbers
must
be
keyed
in,
one
immediately
after
the
other,
use
the
key
again
to
separate
the
first
number
(9)
from
the
second
(3).
(There
is
no
need
to
press
[ENTER]
to
separate
the
9
from
the
previous
intermediate
result
of
13
that
is
already
in
the
calculator—the
results
of
previous
calculations
are
stored
automatically.)
To
solve
(9
~
3):
Keystrokes Display
9 9
9.0000
3 3
8
6.0000
(9-3)
Then
multiply
the
intermediate
results
(13
and
6)
together
for
the
final
answer:
Keystroke Display
Fa] 78.0000
(6+ 7) X(9-3)=78
Notice
that
the
HP-11C
automatically
stored
the
intermediate
results
for
you
and
used
them
on
a
last-in,
first-out
basis
when
it
was
time
to
multiply.
No
matter
how
complicated
a
problem
may
look,
it
can
always
be
reduced
to
a
series
of
one-
and
two-number
operations.
Remember:
©
The
[ENTER]
key
is
used
for
separating
the
second
number
from
the
first
in
any
operation
requiring
the
sequential
entry
of
two
numbers.
e
Any
new
digits
keyed
in
following
a
calculation
are
automatically
treated
as
a
new
number.
~ww
Section 1: Getting Started 25
« Intermediate results are stored on a last-in, first-out basis.
Now try these problems, Work through them as you would with
pencil and paper. Don’t be concerned about intermediate
answers—they are handled automatically by your HP-11C.
(16 X 38)-(13x 11) = 465.0000
(27+63)+(33X9) = 0.3030
(/(16.38 X 0.55) +.05 = 60.0300
4x(17—12)+(10—5) = 4.0000

Section 2
The
Automatic
Memory
Stack,
LAST
X,
and
Data
Storage
The
Automatic
Memory
Stack
and Stack Manipulation
Automatic
retention
and
return
of
intermediate
results
is
the
reason
your
HP-i1C
takes
you
through
complex
calculations
so
easily.
The
features
supporting
this
ease
of
use
are
the
automatic
memory
stack
and
the
[ENTER]
key.
The Automatic
Memory Stack Registers
™>
z>
Y>?
x>
0.0000 | Always displayed.
When
your
HP-11C
is
in
Run
mode
(when
the
PRGM
annunciator
is
not
displayed),
the
number
that
appears
in
the
display
is
always
the
number
in
the
X-register.
Any
number
keyed
in
and
the
result
of
executing
a
numeric
function
is
placed
in
the
displayed
X-register.
Executing
a
function
or
keying
in
a
number
will
cause
numbers
already
in
the
stack
to
lift,
remain
in
the
same
register,
or
drop,
depending
upon
the
type
of
operation
being
performed.
Numbers
in
the
stack
are
available
ona
last-in,
first-out
basis.
If
the
stack
was
loaded
as
shown
on
the
left
of
the
following
illustrations
(as
the
result
of
previous
26
Section 2: Memory Stack, LAST X, and Data Storage 27
calculations),
pressing
the
indicated
keys
would
result
in
the
stack
arrangement
shown
on
the
right
of
each
illustration.*
Stack Lift No Stack Change
lost
Te ]—— 2] ore
Zo
2
|
tes.
See
ee
vals
|—7
[4]
vefa]—-[ay
X>/ 4 | ‘7 789 x>
Keys > 789 Keys >
Stack Manipulation Functions
separates two numbers keyed in one after the other. When
ENTER] is pressed the calculator lifts the stack by copying the
number in the displayed X-register into the Y-register. For
example, to fill the stack with the numbers 1, 2, 3, 4 (assume that
the
stack
registers
have
already
been
loaded
with
the
numbers
shown as the result of previous calculations):
lost lost
Ce) +O)
[7 |7 fe |e | 7]
rel“ +7]
P46] -2142)
(ENTER) 2 (ENTER)
(Illustration continued on next page.)
* To simplify the illustration of features described in this section, a single-digit number
format is used in most of the diagrams instead of the decimal number ([Fix] 4) format
used elsewhere in this handbook.

28 Section 2: Memory Stack, LAST X, and Data Storage
= cal
tT
z>
yo [2 |—+[2 | gan
x> HHH
Keys > (ENTER)
(R8) (roll down), (R#) (roll up), and (X exchange Y). (R¥jand
R4]
rotate
the
contents
of
the
stack
registers
down
or
up
one
register. No values are lost. [x2)] exchanges the numbers in the
X- and Y-registers. If the stack were loaded with the sequence 1, 2,
3, 4, the following shifts would result from pressing (R4)], [9 ][R#],
and (x21).
tof s |
z> Pa}
ee Bean
Keys > RE Rt a
{iStTx] (LAST X). When a numeric function is executed, a copy of the
value occupying the displayed X-register before the function was
executed is stored in the LAST X register. Pressing [9 }{LST.] places
a copy of the current contents of the LAST X register into the
displayed X-register. (Refer to appendix B, Stack Lift and LAST x
for a listing of the functions that save x in the LAST X register.)
For example, if the stack was loaded as shown on the left, below:
Pa
T+[ 0]
He or eS
voto] ze
Xd] 4 |
Keys> aac g a=
goneth
LASTX>
~~
Section
2:
Memory
Stack,
LAST
X,
and
Data
Storage
23
Calculator Functions and the Stack
When
you
want
to
key
in
two
numbers,
one
after
the
other,
you
press
(ENTER)
between
entries
of
the
numbers.
However,
when
you
want
=
key
in
a
number
when
the
number
already
in
the
displayed
X-register
is
the
result
of
a
previous
calculation
or
other
function
(like
,
(RB),
etc.),
you
do
not
need
to
use
(ENTER).
Why?
Executing
almost
any
HP-11C
function
has
two
results:
1. The specified function is executed.
2.
The
automatic
memory
stack
is
enabled;
that
is,
the
stack
will
lift
automatically
when
the
next
number
is keyed
in.
For
example,
with
4
already
keyed
into
the
X-register:
lost
SE
EES
Keys >
There
are
four
functions—(ENTER],
(CLx],
[E+],
and
(2-]—which
disable
the
stack.*
They
do
not
provide
for
the
lifting
of
the
stack
when
the
next
number
is
keyed
in.
Following
the
execution
of
one
of
these
functions,
keying
in
a
new
number
will
simply
write
over
the
currently
displayed
number
instead
of
causing
the
stack
to
lift.
(Although
the
stack
lifts
when
[ENTER]
is
pressed,
it
will
not
lift
when
the
next
number
is
keyed
in.
The
operation
of
[ENTER
illustrated
on
pages
27
and
28
shows
how
[ENTER]
thus
disables
the
stack.)
In
most
cases,
the
above
effects
will
come
so
naturally
that
you
won't
even
think
about
them.
Two-Number Functions
An
important
aspect
of
two-number
functions
is
the
positioning
of
the
numbers
in
the
stack.
To
execute
an
arithmetic
function,
the
numbers
should
be
positioned
in
the
same
way
that
you
would
*
When
pressing
[#]
clears
the
entire
displ.
and
disables
the
stack.
Otherwise,
(€]
is
neutral;
that
is,
it
does
not
affect
the
stack.
For
a
further
discussion of the stack, refer to appendix B, Stack Lift and LAST X.

30 Section 2: Memory Stack, LAST X, and Data Storage
write them on paper. For example, to subtract 15 from 98 you first
write 98 on paper, then write 15 underneath it, like this:
98
ar
Then you would perform the subtraction, like this:
98
15
&3
The numbers are positioned in the calculator in the same way, with
the first number, the minuend, in the Y-register and the second
number, the subtrahend, in the displayed X-register. When the
subtraction function is executed, the 15 in the X-register is
subtracted from the 98 in the Y-register, and the stack drops,
leaving the result in the X-register. Here is how the entire operation
is executed (assume that the stack registers have already been
loaded with the numbers shown as the result of previous
calculations):
lost lost
eel Bice PER
zols | Tia} Tt +[ ore |
yet2 171 beel> feet
xoT | > [as] fee] > Ls] | Les]
98 5 =
Keys > 1
For any arithmetic function, the numbers are always positioned in
their natural order first, then the function is executed and the stack
drops. In the above example, we subtracted 15 from 98, The same
number positioning would be used to add 15 to 98, multiply 98 by
15, and to divide 98 by 15, that is:
~~~
wee vrwve rv
Section 2: Memory Stack, LAST X, and Data Storage 34
98
1S
98
x/S
9%
IS
Chain Calculations
x<No4 5 ae Ae a2
Whether
you
use
your
HP-11C
mostly
for
direct
keyboard
solutions
or
programmed
solutions,
you
are
likely
to
use
chain
calculations
frequently.
It
is
in
this
area
that
the
simplicity
and
power
of
your
HP-11C’s
logic
system
becomes
very
apparent.
Even
during
extremely
long
calculations,
you
still
perform
only
one
operation
at
a
time,
The
automatic
memory
stack
stores
up
to
four
intermediate
results
until
you
need
them,
then
inserts
them
into
the
calculation.
Thus,
working
through
a
problem
is
as
natural
as
if
you
were
working
it
out
with
pencil
and
paper.
You
have
already
learned
how
to
key
in
a
pair
of
numbers
using
the
(ENTER)
key
and
then
perform
a
calculation.
You
have
seen
how
the
stack
drops
as
a
result
of
executing
some
functions
and
how
the
stack
lifts
automatically
when
you
key
in
a
number
after
executing
a
function.
To
see
how
these
features
operate
in
a
chain
calculation,
let’s
solve
3+
6
—
4
+2
=?
(Assume
the
stack
cleared
to
zeros by pressing (#][ENTER][ENTER][ENTER].)
lost
| an rad Bae
SERRE
ERE:
/ yato]--[e] 7a ]+Pey ser
xo] pI] pe
3
‘Keys > ENTER 6 a

32 Section 2: Memory Stack, LAST X, and Data Storage
lost
al a
ate] fe SPH bob
vate Pale
xefe | Pld [5 | Pie
4 2 &
Keys >
As you can see, we worked through the problem one operation at a
time.
The
stack
automatically
dropped
after
each
two-number
calculation. And, after each calculation, the stack automatically
lifted when a new number was keyed in. Even more complicated
problems are solved in the same simple manner.
Example: Instead of the arrow diagrams we've used earlier in this
section, we'll use a table to follow stack operation as we solve the
expression
(8 +4) xX (6-4)
LASTX
The
HP-11C’s
LAST
X
register,
a
separate
data
storage
register,
preserves
the
value
that
was
last
in
the
display
before
execution
of
-~~-~
“Vee
Section 2: Memory Stack, LAST X, and Data Storage 33
a numeric function.*
This feature saves you from having to re-enter numbers you want
to use again and can assist you in error recovery.
Example: To multiply two separate values, such as 45.575 meters
and 25.331 meters by 0.175:
T™>
2 | 0.0000 | 0.0000 | 0.0000 | 6.
Y {0.0000 | 45.5750 | 45.5750] 0.0000 |
x [45.575 [45.5750| 0.175 | 7.9756 |
Keys 45()575 [ENTER] [-]175
LASTX>
\
T™
| 7.9756 | 26.3310 | 7.9756 |
(Est) &
[Ba760) (E750)
Keys® 25.331
* The exceptions are the statistics functions [1], [3], and [LAI].

34
Section
2:
Memory
Stack.
LAST
X,
and
Data
Storage
LSTx]
makes
it
easy
to
recover
from
keystroke
mistakes,
such
as
executing
the
wrong
function
or
keying
in the
wrong
number.
For
example,
divide
287
by
13.9
after
you
have
mistakenly
divided
by
12.9:
Keystrokes Display
287 (ENTER 287.0000
12.9 22.2481 Oops! The wrong divisor.
(a) tstx 12.9000 Retrieves from LAST X
the last entry to the X-
register (the incorrect
divisor) before [-) was
executed.
&)
287.0000
Perform
the
reverse
of
the
function
that
produced
the
wrong
answer.
13.96)
20.6475
The
correct
answer.
Constant Arithmetic
Because
the
number
in
the
T-register
remains
there
when
the
stack
drops,
this
number
can
be
used
as
a
constant
in
arithmetic
operations.
To insert a constant into a calculation, load the stack with the
constant
by
keying
the
constant
into
the
X-register
and
pressing
ENTER]
three
times.
Use
the
constant
by
keying
in
your
initial
argument
and
executing
your
planned
series
of
arithmetic
operations.
Each
time
the
stack
drops,
a
copy
of
the
constant
will
be
made
available
for
your
next
calculation
and
a
new
copy
of
the
constant is reproduced in the T-register.
we eV Ve eV wevn
Section 2: Memory Stack. LAST X, and Data Storage 35
Example: A bacteriologist tests a
certain strain of microorganisms
whose population typically increases
by 15% each day (a growth factor of
1.15). If he starts a sample culture of
1000, what will be the bacteria
population at the end of each day for
five consecutive days?
Method: Use to put the constant growth factor (1.15) in the
Y-, Z-, and T-registers. Then put the original population (1000) in
the displayed X-register. Thereafter, you calculate the new daily
population whenever you press [x]. To set your calculator to the
same display format as is shown in the following example, press [f]
FIx}2.
When you press [x] the first time, you calculate 1.15 X 1000. The
result (1,150.00) is displayed in the X-register, the stack drops, and

36
Section
2:
Memory
Stack,
LAST
X,
and
Data
Storage
a
new
copy
of
the
constant
is
generated
in
the
T-register,
that
is,
each time
you
press
[x]:
1, A new calculation involving
the X- and Y-registers takes
place. Yo [c |
2. The result of the calculation is
placed in the displayed X-
register and the contents of the
rest of the stack drop.
cx
3. Anew copy of the number last
in T (in this case, our constant)
is generated in T.
new c
Since
a
new
copy
of
the
growth
factor
is
duplicated
in
the
T-register
each
time
the
stack
drops,
you
never
have
to
re-enter
it.
Press [f) [FIX] 4 to return the HP-11C to the [Fix]4 display format.
Alternate
Method:
Constant
arithmetic
can
also
be
performed
using
the
LAST
X
register.
To
use
this
method
to
calculate
the
result
of
the
preceding
example:
Key in the original population (1,000) and press (ENTER).
Key in the constant growth factor (1.15).
Press (x]to calculate the population at the end of one day.
ON Press
(8
]
(LSTx]
[x]
to
calculate
the
population
at
the
end
of
each
succeeding
day.
Section 2; Memory Stack, LAST X. and Data Storage 37
Storage Register Operations
Storing and recalling numbers are operations involving the
displayed X-register and the HP-11C’s 21 data storage registers.
Data storage registers are entirely separate from the stack and
LAST X registers.
Storing Numbers
STO] (store). When followed by a storage register address (0
through 9, 0 through ([] 9, or [i)), copies a number from the
displayed X-register into the data storage register specified by the
storage register address.
Data Storage Registers
—h—
Ry Ry
aL] aL]
aL] Ll
aL] ex.)
aL] acl
ny Coe re Loe)
7»CL—] ao
os re ro) |
rpC—_] Ag
a C—]
If... .. and you press
(STO)0, then...
Data Data
Stack Storage Stack Storage
ToL] a
:
HE