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XACT-12C Financial Calculator
The Hewlett-Packard Compatible
Financial Calculator
For Your IBM PC or Compatible
CalcTech Incorporated
6014 NE 60th Street
P.O. Box 15277
Seattle, WA. 98115-0277
Phone: 206-527-9950
Fax: 206-525-1331
Description
XACT-12C is the Financial Calculator of the XACT CALCULATORS
series. XACT CALCULATORS emulate the functions of Hewlett-
Packard's handheld HP-11C Scientific, HP-12C Financial, and
HP-16C Programmer's calculators and include additional features
such as program store to disk, simulated tape display, and
constant memory.
XACT CALCULATORS includes an auxiliary shell program. XSHELL.EXE
is a Terminate-Stay-Resident (TSR) program which loads and runs
all three calculators. (Note: A TSR is a program which remains
loaded but inactive after it finishes execution. TSRs are
usually made active by pressing a "hot-key" which pops up the
program, even if another program is executing at the time).
XSHELL.EXE has 3 hot-keys, one for each calculator.
Normally, the disadvantage of TSRs is that they consume a lot of
your computer's memory, even while they're inactive. Thus if you
have loaded one or more TSRs, there may not be enough RAM left
over to run your spreadsheet, word processor, or other DOS
programs. XSHELL.EXE helps reduce "RAM Cram" because it REQUIRES
ONLY 6K BYTES OF RAM! In fact, If you have EMS memory installed
(see section 2.2) in your computer, XSHELL requires an amazingly
small 1.5K bytes of conventional DOS memory!.
Each calculator can be run individually as an ordinary DOS
program by running either X11.EXE, X12.EXE, or X16.EXE. Or, all
three calculators can be run as a single TSR by running
XSHELL.EXE.
XSHELL.EXE will deactivate and unload itself from RAM after 8
minutes until you register your copy. This will allow you to try
XACT CALCULATORS as a TSR before you register. Once XSHELL.EXE
unloads itself, your computer will behave as though XSHELL had
never been loaded in the first place. To re-activate XSHELL,
simply run the program again. It will again remain loaded for
another 8 minutes.
- 2 -
Quick Registration for XACT CALCULATORS
Registration for XACT CALCULATORS is only $27.00. To register,
print a copy of the file ORDERFRM.DOC and fax or mail the
completed form to us. We will quickly fax (or mail) back your
registration serial number and personal unlock code. Run the
QUICKREG.EXE program entering your name, serial number, and
unlock code and that's it, you're registered! QUICKREG.EXE
serializes XSHELL.EXE and "unlocks" it's 8 minute time limit.
AFTER YOU'VE REGISTERED AND SUCCESSFULLY RUN QUICKREG.EXE,
XSHELL.EXE WILL NO LONGER HAVE AN 8 MINUTE TIME LIMIT. It will
remain resident in your computer's RAM (waiting for a hot-key to
become active) until you reboot or manually unload XSHELL.
If you prefer to order your registered copy by mail, feel free to
mail in your completed form. A copy of the file ORDERFRM.DOC is
shown on the following page.
- 3 -
----------------------------------------------------------------------
FAX this form to: (206)-525-1331
or mail to:
CalcTech, Inc.
6014 NE 60th Street
P.O. Box 15277
Seattle, WA. 98115-0277
----------------------------------------------------------------------
XACT CALCULATORS - Version 5.1
QUICK REGISTRATION FORM
I wish to register my copy of XACT CALCULATORS (includes XACT-11C
Scientific, XACT-12C Financial, and XACT-16C Programmer) today for
$27.00 (Washington state residents add 8.2% sales tax). Please
(check one or more boxes below):
[ ] FAX my serial number and personal unlock code
as soon as possible.
My FAX number is: ____________________________
[ ] Mail my serial number and personal unlock code
as soon as possible.
[ ] Send my registered copy by mail. (Enclose an
an additional $5.00 for U.S. or Canada, $10.00
for overseas air mail). I prefer (check one):
[ ] 5.25" or [ ] 3.5" diskettes
Name: ______________________________ Company:_________________________
Phone: (Day) ______________________ (Evening) ________________________
Address: _____________________________________________________________
City: ______________________________ State: ________ Zip: ____________
Comments: ____________________________________________________________
______________________________________________________________________
(check one): [ ] VISA [ ] Mastercard [ ] Check Enclosed
Credit card #: ____________________________________ Expires: ____/____
Cardholder's Name (Please print): ____________________________________
Cardholder's Signature: ______________________________________________
- 4 -
Background Information
CalcTech, Inc. is a company with a respected history in the
development of software calculators. The article "TSR Desktop
Organizers", (PC Magazine, Aug. 1987), contained a review of the
leading desk accessory programs. Three of the fourteen products
reviewed incorporated calculators developed by CalcTech. A
CalcTech calculator has also won PC Magazine's prestigious
"Editor's Choice" award.
CalcTech has developed calculators for publishers and OEM's such
as Software Publishing Corp., Bellsoft Inc., DAC Software,
Popular Programs Inc., Timeworks Inc., Practical Peripherals, and
Monogram Software.
Here's What A Few Industry Experts Have To Say:
"XACT-16C... It has power to burn." --Johnathan Matzkin, PC
Magazine.
"PC-12C's (OEM version of XACT-12C) emulation of the HP-12C is
exact, it gets my vote." --Jim Seymour, PC Magazine
"I found Bellsoft's (OEM version) Pop-Up calculator to be the
best for office work" --Mark J. Welch, BYTE.
"When a program performs flawlessly, it makes writing a review
hard. Such is the case with XACT CALCULATORS." --Jacques
Benavente, PCM Magazine
XACT CALCULATORS have won PC Brand's 1989 award for outstanding
technical merit in a shareware program.
An Important Note About The Shareware Concept
XACT CALCULATORS are copyrighted shareware programs. They are
not freeware or public domain software. Payment is made through
registration and is on the "honor system". We ask that you pay
for the programs by registration if after a reasonable trial
period, you find them to be useful in your work. We hope that
you appreciate the "try before you buy" concept that shareware
products like XACT CALCULATORS provide and that you will take the
time to register.
Anyone who has ever purchased expensive (or even inexpensive)
software can attest to the frustration of being "burned" by a
lousy product. We think XACT CALCULATORS are excellent products
and we're giving you the opportunity to judge for yourself. If
you agree, please take a moment to register.
- 5 -
Customer Support
Support for XACT CALCULATORS is provided to registered users
using our voice messaging "access code" feature. You can call us
at (206)-527-9950 and leave your question on our voice messaging
system. You will be given an "access code" which is a password
for your message. You may then call back (usually within 1 day),
enter your access code using your touch-tone phone, and receive a
voice message response to your question. Alternatively,
registered users can send your question via E-mail on CompuServe
at 71641,1721 or by U.S. mail.
When contacting customer support, please be as specific as
possible with your question and be sure to mention the version
number of your copy of XACT CALCULATORS.
User Groups, Electronic Bulletin Boards, Disk Vendors
User Groups, BBS SysOps, and Disk Vendors may receive an official
copy of the latest shareware version of XACT CALCULATORS by
submitting a written request to CalcTech, Inc. Please add
CalcTech to your organization's mailing list and send any
appropriate information such as your group's newsletter or
catalog.
Private Labels, Custom Versions
Private labellings and/or custom versions of XACT CALCULATORS can
be developed for your organization. Please contact CalcTech,
Inc. by in writing for a quotation.
Government, Corporate, Academic Site Licensing
A site license grants you the legal right to make multiple copies
of a "master" registered version and it's documentation for your
organization or group.
A site license is non-transferable. We accept Visa and
Mastercard, personal or corporate checks, and written (fax ok)
purchase orders (NET 30, FOB Seattle, WA.) for site license
registration. The following page is a site license form you can
use to fax or mail or mail to us for site licensing.
- 6 -
----------------------------------------------------------------------
FAX this form to: (206)-525-1331
or mail to:
CalcTech, Inc.
6014 NE 60th Street
P.O.Box 15277
Seattle, WA. 98115-0277
----------------------------------------------------------------------
XACT CALCULATORS - Version 5.1
Site License Registration Form
Use this form to obtain a site license for your company or
group. Your registered copy will be sent via U.S. mail.
I wish to register XACT CALCULATORS under a multiple (site)
license agreement. Please license my organization to allow
us to duplicate up to: (check one)
[ ] 10 copies .................................... $100.00
[ ] 100 copies ................................... $350.00
[ ] 1000 copies ................................. $1000.00
WA. state residents add 8.2% ................ $_______
TOTAL $_______
Company or Group Name: _______________________________________________
Your Name: ___________________________________ Phone: ________________
Address: _____________________________________________________________
City: ______________________________ State: _________ Zip: ___________
Method of Payment: (check one)
[ ] Check enclosed
[ ] Bill Me. Terms are NET 30, FOB Seattle, Washington
Our Federal taxpayer I.D. number is: 91-1382828
Purchase Order Number (optional): ___________________________
[ ] Charge my Visa or Mastercard
Cardholder's Name: __________________________________________
Credit Card #: ____________________________ Expires:____/____
- 7 -
License Agreement
You are hereby granted permission to use this software and to
distribute copies of the software and documentation in its
original form as long as it is not distributed for profit
(handling fees less than $5.00 are ok). ONLY COPIES OF THE
SHAREWARE VERSION OF THIS SOFTWARE AND DOCUMENTATION MAY BE
DISTRIBUTED IN ANY FORM. You are not allowed to make copies
(except for backup purposes only) or distribute this software and
documentation once the software has been registered.
THE SOFTWARE HEREIN ARE PROVIDED "AS IS" WITHOUT WARRANTY OF ANY
KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO,
THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND
PERFORMANCE OF THE PROGRAMS IS WITH YOU.
IN NO EVENT SHALL CALCTECH OR ANY OF IT'S OFFICERS, DIRECTORS,
SHAREHOLDERS, EMPLOYEES, AFFILIATES, OWNERS, OR OTHER RELATED
PARTIES BE LIABLE TO YOU OR ANY OTHER THIRD PARTY FOR DAMAGES
INCLUDING ANY LOST PROFITS, LOST SAVINGS, OR OTHER INCIDENTAL OR
CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OF OR THE INABILITY
TO USE THIS PRODUCT OR AS TO THE PERFORMANCE OF THIS PRODUCT EVEN
IF WE HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES IN
ADVANCE.
SOME STATES DO NOT ALLOW THE LIMITATION OR EXCLUSION OF LIABILITY
FOR INCIDENTAL OR CONSEQUENTIAL DAMAGES SO THE ABOVE LIMITATION
OR EXCLUSION MAY NOT APPLY TO YOU.
THIS AGREEMENT IS GOVERNED BY THE LAWS OF THE STATE OF
WASHINGTON.
Trademarks/Copyrights
HP-11C, HP-12C, and HP-16C are trademarks of Hewlett-Packard Co.
Lotus is a trademark of Lotus Development Corp.
Intel is a trademark of the Intel Corp.
PC-DOS, IBM-PC, PC-XT, PC-AT and PS/2 are trademarks of IBM.
MS-DOS, Microsoft Windows and Microsoft Word are trademarks
of Microsoft Corp.
Copyright (C) 1987-1990, 1991 by CalcTech Inc.
All rights reserved.
Specifications herein are subject to change without notice.
- 8 -
TABLE OF CONTENTS
Section Title Page
1. Getting Started .......................................... 11
1.1 Introduction ......................................... 11
1.2 Other Guides ......................................... 11
1.3 System Requirements .................................. 12
1.4 Installing XACT-12C and Making Backups ............... 12
1.5 Command Line Options & Changing Hot Keys ............. 12
1.6 Using XACT-12C with Microsoft Windows ................ 13
1.7 Using XACT-12C on a Network .......................... 13
2. Loading XACT-12C .......................................... 14
2.1 XACT-12C Shareware Version ........................... 14
2.2 XACT-12C as a TSR Program ............................ 14
2.3 XACT-12C as a Removable TSR Program .................. 15
3. XACT-12C Basics ........................................... 16
3.1 Keyboard Conventions ................................. 16
3.2 Function Keys ........................................ 16
3.3 Prefix Keys .......................................... 16
3.4 Entering Numbers ..................................... 17
3.5 Short Cut Keys ....................................... 17
4. Basic Operations .......................................... 17
4.1 Setting the Display Format ........................... 17
4.2 Arithmetic Calculations and RPN ...................... 17
4.3 Clearing Numbers ..................................... 18
4.4 Negative Numbers ..................................... 19
4.5 Mathematical Operations .............................. 19
4.6 Exponential Notation ................................. 19
4.7 Memory Storage Registers ............................. 19
4.8 Stack Operations ..................................... 20
4.9 The LastX Register ................................... 20
- 9 -
Section Title Page
5. Features .................................................. 21
5.1 Getting Help ......................................... 21
5.2 Viewing the Tape ..................................... 21
5.3 Printing the Tape .................................... 21
5.4 Storing the Tape ..................................... 21
5.5 Loading a Program .................................... 21
5.6 Storing a Program .................................... 22
6. Financial Calculations .................................... 22
6.1 Financial Registers and Functions .................... 22
6.2 Cash Flow Notation ................................... 23
6.3 Percentage Operations ................................ 23
6.4 Simple Interest ...................................... 24
6.5 Compound Interest .................................... 24
6.6 Amortization ......................................... 27
6.7 Net Present Value .................................... 28
6.8 Internal Rate of Return .............................. 29
7. Bond Calculations ......................................... 29
7.1 Bond Yield ........................................... 29
7.2 Bond Price ........................................... 30
8. Statistical Calculations .................................. 30
8.1 Entering and Removing Numbers ........................ 30
8.2 Statistical Mean ..................................... 31
8.3 Statistical Weighted Mean ............................ 31
8.4 Standard Deviation ................................... 32
8.5 Linear Estimate ...................................... 33
9. Calendar Calculations ..................................... 33
9.1 Days between Dates ................................... 33
9.2 Date Calculations .................................... 33
10. Programming .............................................. 34
10.1 Introduction to Programming .......................... 34
10.2 Entering a Program into XACT-12C ..................... 34
10.3 Program Loops and Branches ........................... 36
11. Appendix ................................................. 37
11.1 Error Conditions ..................................... 37
- 10 -
1. Getting Started
1.1 Introduction
XACT CALCULATORS are software which emulate the functions of the
handheld models of Hewlett-Packard's HP-11C Scientific, HP-12C
Financial, and HP-16C Programmer's calculators. If you are
familiar with one or more of these calculators, you will find
that you already know how to use XACT CALCULATORS. If not,
you'll find XACT CALCULATORS easy to learn and use. They will
become an invaluable tool in your work.
XACT-12C is the Financial Calculator program. XACT CALCULATORS
also incorporate the XACT-11C Scientific Calculator and the
XACT-16C Programmer's calculator.
If you are already familiar with DOS and with the HP-12C, you may
only need to read Chapters 2 and 3. This will provide enough
information to get you started.
If you are new to DOS and/or the HP-12C, you may wish to read, or
at least skim, Chapters 1 through 6.
1.2 Other Guides
There are a number of guides and references available for the
HP-12C that can be used with XACT-12C as well. These are
generally available in bookstores and other places where Hewlett-
Packard calculators are sold. Some of these publications are
listed below.
"HP-12C Owner's Handbook and Problem Solving Guide" Covers
general operations, functions, applications, and programming of
the HP-12C. Published by the Hewlett-Packard Company.
HP-12C Solutions Handbook" Supplement to the Owner's Handbook and
Problem Solving Guide. Applications include real estate,
lending, savings, investment analysis, securities, forecasting,
pricing, statistics, personal finance, and more. Published by
the Hewlett-Packard Company.
"HP-12C Training Guide" Tutorial introduction to the HP-12C
containing lots of examples. Published by the Hewlett-Packard
Company.
"An Easy Course in using the HP-12C" by Coffin/Wadman. Published
by Grapevine Publishing, Inc. P.O. Box 118, Corvallis, OR, 97339.
- 11 -
1.3 System Requirements
To operate the XACT-12C calculator, you will need an IBM PC, PC-
XT, PC-AT, PS/2, or close compatible equipped with at least the
following:
256K RAM
PC-DOS or MS-DOS version 3.00 or later
1.4 Installing XACT CALCULATORS and Making Backups
You should make a copy of the programs contained on the XACT
CALCULATORS diskette for backup purposes. Use the DOS "copy"
command to copy all the files to another diskette or to your hard
disk. There may be a file named README.DOC on your disk. If so,
you should examine it using your word processor or the DOS "type"
command.
1.5 Command Line Options/Changing Hot-Keys
A command line option is an additional command typed when you
first load X12.EXE or XSHELL.EXE. There are several of these
options available. For example, if you wish to start XACT-12C in
monochrome mode, you would type:
x12 /mono [ENTER]
The following is a list of available command line options when
running XACT-12C.
/mono Force XACT-12C into monochrome mode
/sci Start up in scientific notation (XACT-11C only)
/nomouse Disable mouse operation
/nosignon Disable the signon screen
/swap=<path> Directory/Path used to store swap files
There are additional command line options available when running
the program XSHELL.EXE. The following is a list of these
options.
/alt Changes invocation key to Alt-s (XACT-11C),
Alt-f (XACT-12C), Alt-p (XACT-16)
/alt-ctrl Change invocation key to Alt-Ctrl-s (XACT-11C),
Alt-Ctrl-f (XACT-12C), Alt-Ctrl-p (XACT-16C)
/mono Force XACT CALCULATORS into monochrome mode
/sci Set scientific notation (XACT-11C only)
/noems Disable EMS memory usage (if EMS memory present)
/nomouse Disable mouse operation
/nosignon Disable the signon screen
/swap=<path> Directory/Path used for swap files. (See section
on using XACT CALCULATORS on a network)
/wsize=nn Set word size (XACT-16C only). Valid settings
- 12 -
for nn are 2 to 64.
/radix=n Set radix (XACT-16C only). Valid settings for
n are h,d,o,b, or f (hex,dec,oct,bin,float)
1.6 Using XACT-12C with Microsoft Windows
If you use Microsoft Windows, you may wish to set up Windows to
run XACT-12C. XACT-12C will run as an ordinary "text mode"
application under Windows which can be set up to be either
windowed or in full screen mode.
To run XACT-12C under Windows, you should first create a PIF file
which is used to "describe" the program to Windows. Use the PIF
editor (pifedit.exe) to create an x11.pif file. For the
"optional parameters" field, type in /nosignon so that XACT-12C
won't display it's startup screen every time you click on it's
icon. Also make sure that the "KB required" field is set to 128.
(For additional information on using the PIF editor, see your
Windows documentation).
Once you have created a PIF file, you will probably want to
create an icon so you can easily invoke XACT-12C by double
clicking on an icon. We have supplied a custom icon you can use
to do this. From the Windows program manager, create a new
program item and in the "command line" field, type in x12.pif.
Then select the "change icon" button and type in xact.ico. (If
you're unclear on these procedures, they're also covered in
Microsoft's Windows documentation).
1.7 Using XACT-12C on a Network
XACT-12C and all XACT CALCULATORS are compatible with most
networks. If you wish to use them on a network, read the
following information.
All XACT CALCULATORS use a technique known as swapping in order
to save memory as well as save the state of each calculator each
time you finish using it. Swapping creates a number of
"temporary" files. By default, these files are saved in the same
directory as the XACT CALCULATOR programs themselves. If two or
more users on a network are running a calculator, their swap
files will eventually corrupt each other, causing unpredictable
results. There are 2 different ways to avoid this problem. Both
involve changing the directory in which the swap files are
stored.
The first method is by using an environmental variable to tell
XACT CALCULATORS the path to use to store its swap files. For
example, assume you have 2 network users (Jan and Bill) each of
which have access to network drive N:. Assume also that the
directorys N:\USER\JAN\TEMP and N:\USER\BILL\TEMP have already
- 13 -
been created on drive N: The environmental variable can be set
by putting the following statement in Jan's AUTOEXEC.BAT file:
SET XACT=N:\USER\JAN\TEMP
whereas Bill's AUTOEXEC.BAT file would contain the statement:
SET XACT=N:\USER\BILL\TEMP
Now even though Jan and Bill may be running the same copy of one
of the calculators, they would each have separate copies of swap
files and there would be no conflict.
The second method uses the same idea, however, the swap path is
chosen from the command line. For example:
X12 /SWAP=C:\TEMP
would place the swap files in the directory C:\Temp, assuming it
existed.
2. Running XACT-12C
2.1 Running XACT-12C as a stand-alone DOS program
To run XACT-12C, at the DOS prompt type:
x12 [ENTER]
2.2 Running XACT-12C as a TSR program
To run XACT-12C as a TSR program, type
xshell [ENTER]
You will see the copyright message appear on the screen. The
computer will then return to the DOS prompt and appear as if
nothing had happened. However, the XACT CALCULATORS shell
program has now been loaded into your computer's memory. To
activate XACT-12C, press:
Alt-Shift-F
XACT-12C will now appear on your screen, ready to perform
calculations. To exit from XACT-12C, press the Esc key. In a
likewise fashion, to run the XACT-11C scientific calculator, you
would instead press Alt-Shift-S, and to run the XACT-16C
Programmer's calculator you would press Alt-Shift-P. You can
also unload XSHELL from RAM by pressing Alt-Shift-U.
- 14 -
When you run XSHELL, it will use between 1.5K and 6K bytes of
your computer's RAM. To determine exactly how much memory XSHELL
is using, you can run the DOS command "chkdsk" both before and
after running XSHELL and noting the difference in memory bytes
free. If you are unfamiliar with this command, see your DOS
reference manual.
EMS (Expanded memory specification) memory is a type of memory
specification that was developed jointly by Lotus, Intel, and
Microsoft. EMS memory was developed as a work-around to get
around the 640K DOS memory limitation. In order to use EMS
memory, a program must be written specifically to use EMS memory
(if available). XSHELL is such a program. If you have an EMS
memory board installed in your computer, XSHELL will put as much
of itself in EMS memory as it can and will also "swap" your
computer's memory to EMS memory when you pop-up a calculator.
With EMS memory installed, XSHELL will require less than 1.5K of
DOS memory!. If you don't have EMS memory but have a 386
computer, there are several commercial programs available which
can "simulate" EMS memory.
Even if you don't have EMS memory installed, XSHELL requires less
than 6K bytes of DOS memory. Without EMS memory, XSHELL will
swap to disk, creating the file XSHELL.SWP. This file may be as
large as 131k bytes.
If you have not registered your copy of XACT CALCULATORS, you
will only be able to use them as a TSR program for 8 minutes
before they automatically unload themselves from memory. After 8
minutes, you will hear a tone telling you that XSHELL is
unloading. You will have to run XSHELL again in order to use
XACT CALCULATORS as a TSR. Once you have registered and received
your serial number and unlock code, you can enter these numbers
into the program QUICKREG.EXE which will remove the 8 minute
limit from XSHELL. You can always run X12.EXE as a (non-TSR) DOS
program without any limitations whatsoever.
2.3 XACT-12C as a Removable TSR Program
When the shell program is loaded as a TSR program as in section
2.1 above, it remains loaded in your computer's memory until your
computer is rebooted or powered off. To unload the shell
program, press:
Alt-Shift-U
Unloading the shell program will not work if any other TSR
programs have been loaded after XSHELL.EXE. Unfortunately, this
is a limitation of DOS itself.
- 15 -
3. XACT-12C Basics
3.1 Keyboard Conventions
Throughout this manual, XACT-12C function keys are denoted within
a box. For example, the function key for amortization
calculations is shown as [AMORT]. In the case of function keys
which require a prefix key (discussed in the next section), the
prefix key is not given in this manual since it can easily be
determined.
Keys on the PC keyboard are listed in this manual using single
quotes such as 'a'. Numbers to be entered into XACT-12C are
shown in normal type.
3.2 Function Keys
XACT-12C has approximately 70 different function keys arranged in
the same ordering as on the HP-12C. Function keys are arranged
in groups of up to 3 functions per key; an upper, a lower and a
middle function all correspond to one function key. The upper
and lower functions are invoked by first pressing a prefix key
(discussed in the next section) and then the function key. The
middle function does not require the use of a prefix key. The PC
keystroke corresponding to function key is shown immediately to
the left of the function box.
The first row of function keys use the PC keys F1 through F10.
The second through fourth rows use the alphabetic characters as
arranged left to right on your PC keyboard.
For example, the [Clx] function on XACT-12C is invoked by
pressing the letter 'g' on the PC keyboard. Likewise, the [Rcl]
function is invoked by pressing the letter 'b'. The [PV]
function is invoke by pressing F3.
3.3 Prefix Keys
The left shift key and the right shift key on the PC keyboard
operate as prefix keys. They are equivalent to the gold [f] key
and the blue [g] key on the HP-12C. Prefix keys allow you to
activate the upper and lower functions assigned to a PC function
key. For example, to invoke the [SOYD] function, you would press
and release the left shift key, and then press the letter 'r'.
Likewise, to invoke the [Frac] function, you would press and
release the right shift key and then press the letter 'r'. To
invoke the [NPV] function, press and release the left shift key,
and then press F3.
- 16 -
3.4 Entering Numbers
To enter numbers into XACT-12C, use the numeric keypad on the
right side of your keyboard or the numbers on the typewriter
portion of the keyboard.
3.5 Short Cut Keys
You can use the Enter key on the PC, (also known as the Return
key) as the XACT-12C [ENTER] key as a short cut. Also, the '+',
'-', '*', and '/' keys adjacent to the numeric keypad function as
you would expect.
4. Basic Operations
4.1 Setting the Display Format
When you first start it up, XACT-12C defaults to displaying 2
digits to the right of the decimal point. To change this
setting, press the [Fix] function key followed by a number from 0
to 9 (enter numbers using the numeric keypad). This number
represents the number of digits displayed to the right of the
decimal point. Note that the display format does not affect the
number of digits used to perform calculations, only the way in
which they are displayed. If you were using a 2 digit display
format, the number 12.006 would be shown on the display as 12.01.
In this example, the display has been rounded to 2 digits past
the decimal point. However, the internal representation of the
number is still kept as 12.006, and this value would be used in
subsequent calculations.
To round the number internally to match the number in the display
use the [Rnd] key. In the above example, if the [Rnd] key were
pressed, the internal value 12.006 would be converted to 12.01.
4.2 Arithmetic Calculations and RPN
You may already be familiar with Reverse Polish Notation (RPN).
RPN is a type of calculator logic that eliminates the need for
the equals key and the use of parenthesis in computations.
Instead, multiple operands are entered into the calculator
separated by the [ENTER] key. For example, to add the numbers 3
and 4:
Keystroke Display Comment
================================================================
3 [ENTER] 3.00
4 [ + ] 7.00 Add 3 + 4
- 17 -
The result, 7.00 is now displayed. To multiply this result by 5:
Keystroke Display Comment
================================================================
5 [ * ] 35.00 7.00*5.00
The way that XACT-12C performs these calculations with RPN is by
using a stack. The stack consists of 4 registers: X, Y, Z, and
T. It is not generally necessary to understand the internal
workings of the stack but for completeness they will briefly be
discussed below.
Any number displayed is said to be in the X register. When the
[ENTER] key is pressed, a number in the X Register is pushed into
the Y Register and the previous number in the Y Register is
pushed into the Z Register. The previous number in the Z
register is pushed into the T Register. T stands for "Top" and
represents the top of the stack of numbers. The previous value
of the T register is lost. When a function key such as the [+]
key is pressed, the value held in the Y register is added to the
X register and this result is now stored in the X register.
Pressing [ENTER] does one other thing, it leaves the stack
disabled. This means that a number entered after the [ENTER] key
has been pressed is not pushed on the stack, it remains in the X
register. Most operations enable the stack so that when a new
number is entered, the previous contents of the X register are
pushed into the Y register. The most notable exceptions to this
rule are the [ENTER] and the [Clx] function keys.
4.3 Clearing Numbers
You can clear a number in the display by pressing the [Clx]
function key. The calculator is now ready to accept another
entry. Unlike other calculators, XACT-12C does not require a key
for clearing a number and a different key for clearing the last
entry. Whether you have made a mistake in adding a series of
numbers, or simply wish to start a new calculation, use the [Clx]
function key. XACT-12C also contains other function keys to
clear the following:
[S] Clear Sum. Used to clear the statistical registers
when perform statistics calculations.
[Prgm] Clear Program. Used to clear the program memory when
programming XACT-12C.
[Fin] Clear Financial Registers. Used to clear the financial
registers when performing a new compound interest
calculation.
[Reg] Clear Registers. Used to clear all registers; display,
stack, memory, financial, and LastX. This key is used
when beginning a new [NPV] or [IRR] calculation, as
well as various other places.
- 18 -
4.4 Negative Numbers
To change the sign of a number in the display, press the [ChS]
(Change Sign) function key. The [ChS] function will toggle the
sign of the value in the display. The [ChS] key is also used to
change the sign of an exponent if you are using exponential
notation.
4.5 Mathematical Operations
XACT-12C contains a number of commonly used mathematical
operations.
[x] Square root of a number.
[Ln] Natural log of a number.
[e^x] Exponential of a number.
[1/x] Reciprocal of a number.
[Intg] Return the integer portion of a number.
[Frac] Return the fractional portion of a number.
[y^x] Raise a number to a power of another number.
4.6 Exponential Notation
Use exponential notation to enter very large or very small
numbers into XACT-12C. The [Eex] function key is used to enter
an exponent. For example, to enter the number 12 * 10**9
(12,000,000,000) type:
Keystroke Display Comment
================================================================
12 [EEx] 9 12.00 +09
Likewise, to enter the number 12-09, you would type:
Keystroke Display Comment
================================================================
12 [EEx] 9 12.00 +09
[ChS] 12.00 -09
4.7 Memory Storage Registers
XACT-12C contains 20 different memory storage registers, used to
perform storage and memory arithmetic calculations. These
memories will retain their values until your computer is powered
off or re-booted. Memory registers in XACT-12C are referred to
as R0-R9 (for register 0 through 9), and R.0 through R.9. For
example, to store the value 20.3 in memory register 2, type:
- 19 -
Keystroke Display Comment
================================================================
20.3 [Sto] 2 20.30
To add the number 9.6 to the contents of register 2, type:
Keystroke Display Comment
================================================================
9.6 [Sto] [ + ] 2 9.60
Now, if you wish to view the contents of memory register 2, type:
Keystroke Display Comment
================================================================
[Rcl] 2 29.90
Memory register 2 contains the value 29.90.
4.8 Stack Operations
The [x<>y] function exchanges the contents of the X and Y
registers. The [R|] (shown on XACT-12C as an R followed by an
arrow pointing downward) function rolls down the stack. The T
register is copied into the Z register. The Z register is
copied into the Y register, and the Y register is copied into
the X register. The X register is "rolled around" into the T
register.
4.9 The LastX Register
The [Lstx] function key is not technically a part of the stack.
It is used to recover numbers entered just before a mathematical
operation was performed on the stack. The number recovered is
held in a register referred to as the LastX register. For
example, assume you meant to add the numbers 12 and 5 but
accidentally pressed 6 instead of 5.
Keystroke Display Comment
================================================================
12 [ENTER] 12.00
6 [ + ] 18.00 Wrong value
[Lstx] 6.00
[ - ] 12.00 Subtract
5 [ + ] 17.00 Correct result
- 20 -
5. Features
5.1 Getting Help
A Help menu is available when you are working with XACT-12C. To
obtain help press:
Alt-F1
An information screen will appear in a window. The help menu can
be removed by pressing F1 again.
5.2 Viewing the Tape
XACT-12C provides a simulated tape display which keeps a record
of your calculations as you perform them. To view the tape
press:
Alt-F2
The tape will appear in a window. To remove the tape, press F2
again.
The calculator will disappear and the number in the display will
be fed to your application.
5.3 Printing the Tape
To print the tape as you make calculations press:
Alt-F5
To turn off printing, press F5 again.
5.4 Storing the Tape
The simulated tape may be saved to a disk file as you make
calculations. Each time you use XACT-12C, calculations are
appended to the tape file. To store the tape, press
Alt-F6
The tape will be saved under the name X12.ASC in the directory
which you started XACT-12C in.
5.5 Loading a Program
To load a program previously saved press:
- 21 -
Alt-F7
A window will appear requesting a file name. Enter the DOS
filename of the program you wish to retrieve.
5.6 Storing a Program
XACT-12C allows you to save programs as disk files. To save a
program on disk, press:
Alt-F8
A window will appear prompting you for comments. You can enter
up to 3 lines of comments, associated with the program you are
saving. Press the Esc key after you have entered any comments.
Another window will appear prompting you for a filename. Enter
any valid DOS filename.
6. Financial Calculations
6.1 Financial Registers and Functions
XACT-12C contains a number of financial registers. These
registers are function keys used for storing values and for
computing compound interest problems. The financial registers are
summarized here:
[PV] Store/Calculate Present Value
[FV] Store/Calculate Future Value
[I] Store/Calculate the Interest Rate per
compounding period
[N] Store/Calculate the Number of periods
In addition, there are a number of additional function keys used
for financial calculations:
[AMORT] Calculate Amortization
[INT] Calculate simple Interest
[NPV] Calculate Net Present Value
[IRR] Calculate Internal Rate of Return
[PRICE] Calculate the Price of a Bond
[YTM] Calculate the Yield To Maturity of a Bond
[SL] Calculate Straight Line Depreciation
[SOYD] Calculate Sum of Years Digits Depreciation
[DB] Calculate Declining Balance depreciation
- 22 -
6.2 Cash Flow Notation
Compound interest calculations involve both the paying and
receiving of monies. For example if you take out a loan, you
initially receive money from the bank, then you must pay money
to the bank at periodic intervals. Likewise if you deposit
money into a savings account, you are paying money into that
account and receiving money later in terms of what you have
earned as principal and interest.
There is a convention used within XACT-12C to designate the
paying and receiving of monies when calculation compound interest
calculations. Money paid is always a negative number, since it
is being subtracted from a source. Likewise, money received is a
positive number. Thus when entering or calculating a problem
using the [PV] the [FV] or the [PMT] registers, you should
observe the proper sign convention. This concept will become
clear in the examples of section 6.5.
6.3 Percentage Operations
XACT-12C performs several different types of percentage
calculations. The [ % ] function calculates the percent amount
of a number. The [D%] (shown on XACT-12C as Greek letter "delta",
a small triangle character) calculates the difference in percent
one number is from another, and is used in percentage markup and
discount calculations. The [%T] calculates the percentage a
number is of a total of numbers.
Example: Determine the total amount you would pay for a $39.95
radio if the sales tax is 8.1%.
Keystroke Display Comment
================================================================
39.95 [ENTER] 39.95
8.1 [ % ] 3.24 Sales tax
[ + ] 43.19 Total paid.
You would pay $43.19 including sales tax.
Example: What is 20% of $3500.00?
Keystroke Display Comment
================================================================
3500 [ENTER] 3500.00
20 [ % ] 700.00
Example: Gasoline prices fell last month from an average of $1.09
to $.98. What percent difference does this represent?
- 23 -
Keystroke Display Comment
================================================================
1.09 [ENTER] 1.09
.98 [D%] -10.09
Gasoline prices have fallen 10.09%.
Example: If last year, you spent $640.00 on gasoline for your
car, $340.00 in insurance, and $448.00 in maintenance and repair,
what percentage of your total automotive costs were spent on
gasoline?
Keystroke Display Comment
================================================================
640 [ENTER] 640.00 Gasoline
340 [ + ] 980.00 Plus insurance
448 [ + ] 1428.00 Plus repair
640 [%T] 44.82
You spent nearly 45 percent on gasoline.
6.4 Simple Interest
Simple interest calculations involve calculations where interest
is not compounded over a number of periods but rather is a single
fixed amount over a fixed period of time. Simple interest can
be computed either using a 360 day year or a 365 day year.
Example: Suppose you wish to compute the amount owed on a 180
day loan of $5000.00 computed using 12% simple interest. Assume
that interest is calculated using a 360 day year.
Keystroke Display Comment
================================================================
5000 [ChS] [PV] -5,000.00 Loan amount
180 [ N ] 180.00 Loan period
12 [ I ] 12.00 Interest rate.
[INT] 300.00 Interest, 360 Day basis
[ + ] 5,300.00 Total amount
The amount owed, including interest is 5,300.00. If you wished
to compute the interest based on a 365 day year, you would press
the [R|] (roll down) key sequence after pressing [Int].
6.5 Compound Interest
Compound interest calculations involve monies where interest is
computed at regular compounding periods. A compounding period
may be a day, month, year, etc. The more often interest is
compounded, the greater the amount of interest payment since
interest is being earned/paid on interest.
- 24 -
XACT-12C uses the [PV] [FV] [PMT] [N] and [I] registers in
compound interest calculations. Any of four of the variables
must be known and the fifth one can then be calculated.
In calculations where the compounding period is monthly and the
length of annuity or interest rate are given in years, XACT-12C
provides two convenient short cut function keys. The [12x] key
is used to store the number of years and the [12/] is used to
store the annual interest rate.
In addition, the [Beg] and [End] function keys can be used for
when interest is to be compounded at the Beginning of a compound
period (annuity due), or at the End of a compounding period
(ordinary annuity). When first loaded, XACT-12C is in End mode.
To change to Begin mode, you would press the [Beg] function key.
When you do so, the letters "Beg" will be shown to the right of
the display to remind you that you are in Begin mode. To change
back to End mode, press [End].
A number of compound interest calculation examples are shown
below.
LOAN CALCULATIONS
Example: Suppose you wish to take out a home improvement loan.
Calculate the monthly payment if your loan is for $7500 at 9%
annual interest compounded monthly over 4 years.
Keystroke Display Comment
================================================================
[Fin] Clear finance registers
7500 [PV] 7,500.00 Store PV amount
[End] 7,500.00 Use "end" mode
9 [12/] 0.75 Interest rate/period
4 [12x] 48.00 Number of periods
[PMT] -186.64 Monthly payment.
Example: How much could you afford to pay for a new car if you
could afford $300.00 monthly payments. Assume a 4 year loan with
6% interest compounded monthly.
Keystroke Display Comment
================================================================
[Fin] Clear finance registers
300 [ChS] [PMT] -300.00 Monthly payment
6 [12/] 0.50 Monthly interest rate
4 [12x] 48.00 Number of periods
[PV] 12,774.10 Purchase price
You could afford to spend as much as $12,774.10 for your car.
- 25 -
Example: Calculate the Annual Percentage Rate (APR) on a 20 year
home loan of $125,000 at 9.5% interest. Assume the loan fee is
1.5%.
Keystroke Display Comment
================================================================
[Fin] Clear registers
[End] End mode
125000 [PV] 125,000.00 Amount of loan
9.5 [12/] 0.79 Monthly interest
20 [12x] 240.00 Number of months
[PMT] -1,165.16 Monthly payment
[Rcl] [PV] 1.50
[ % ] [ - ] [PV] 123,125.00 Amount less loan fee
[ I ] 0.81 Monthly interest
12 [ * ] 9.72 APR interest
The APR interest rate is 9.72%.
Example: Suppose you purchased a home 7 years ago for $75,000.
You have just sold the home for 124,000. In terms of monthly
compound interest rate, how much has the home appreciated?
Keystroke Display Comment
================================================================
[Fin] Clear finance registers
[End] End mode
75000 [ChS] [PV] -75,000.00 Purchase price
124000 [FV] 124,000.00 Sell price
7 [12x] 84.00 Number of months
[ I ] 0.60 Monthly interest rate
12 [ * ] 7.20 Annual interest rate
The home has appreciated at an annual rate of 7.2%.
SAVINGS CALCULATIONS
Example: Suppose you presently have $9600 in your savings
account. You have just received a raise and are able to make
monthly deposits of $400 into this account. How long will it be
before you have $17000 if your account earns 6.50% interest
compounded quarterly?
Keystroke Display Comment
================================================================
[Fin] Clear finance registers
9600 [ChS] PV 9,600.00 Beginning amount
400 [ChS] [PMT] 400.00 Monthly deposit
6.5 [ENTER] 4 [/] [I] 1.63 Interest rate per period
17000 [FV] 17,000.00 Future value
[ N ] 13.00 Number of months
- 26 -
It would take 13 months to reach $17,000 in your account.
Example: How much will you have to save each month in order to
have $3500 at the end of 14 months. Assume you make equal
monthly deposits into a new savings account that earns 5.5%
interest compounded monthly.
Keystroke Display Comment
================================================================
[Fin] Clear finance registers
3500 [FV] 3,500.00 Future value
14 [N] 14.00 14 periods
5.5 [12/] 0.46 Interest rate/period
[PMT] -242.64 Monthly deposit
You would have to save $242.64 per month.
6.6 Amortization
XACT-12C can produce a loan amortization schedule using it's
built in [AMORT] function. To perform an amortization
calculation, you must:
1- Enter the loan amount, interest, and payment amount.
2- Enter the number of payments to amortize and press
[AMORT] to display the interest amount paid toward the loan.
3- Press the [x<>y] function to display the principal amount paid
toward the loan.
4- Press [Rcl] [PV] to display the balance of the loan.
Example: Suppose you have purchased an automobile for $23,000
at 7.5% interest compounded monthly on a 4 year loan. Find the
amount you will have paid in interest and principal on the loan
after 10 months and after 20 months.
Keystroke Display Comment
================================================================
[Fin] Clear registers
[End] End mode
23000 [PV] 23,000.00 Loan amount 7.5
[12/] 0.63 Interest per month
4 [12x] 48.00 Number of months
[PMT] -556.11 Monthly payment
10 [AMORT] -1,319.57 Interest paid 10 mo.
[x<>y] -4,241.53 Principal paid 10 mo.
[Rcl] [PV] 18,758.47 Balance
10 [AMORT] -1,046.90 Interest paid 20 mo.
[x<>y] -4,514.20 Principal paid 20 mo.
[Rcl] [PV] 14,244.27 Balance 20 mo.
After 10 months, you would have paid $1,319.57 in interest,
$4,241.53 in principal, and have a remaining balance of
- 27 -
$18,758.47. After 20 months, you would have paid an additional
$1,046.90 in interest, $4,514.20 in principal, and have a
remaining balance of $14,244.27.
6.7 Net Present Value
The [NPV] function calculates the net present value of a series
of cash flows, made at regular intervals. It is most commonly
used to perform an analysis between a variety of investment
opportunities. A negative NPV represents a loss on the
investment.
Example: Suppose that you wanted to buy a business for $150,000
and sell it after 4 years. If you project that your cash flows
will be -7,500 after the first year, $9,000 after the second,
$28,000 after the third, and finally $164,000 after the fourth,
would you be receiving at least 12% return?
Keystroke Display Comment
================================================================
[Reg] Clear registers
150000 [ChS] [CFo] -150,000.00 Initial cash outlay
7500 [ChS] [CFj] 7,500.00 1st cash flow
9000 [CFj] 9,000.00 2nd cash flow
28000 [CFj] 28,000.00 3rd cash flow
164000 [CFj] 164,000.00 4th cash flow
12 [ I ] 12.00 Desired interest rate
[NPV] -11,974.01 Net Present Value.
Since the result is a negative number, the desired 12% rate would
not be achieved.
The [Nj] function can be used when there are a number of times in
which the same cash flow occurs.
Example: Suppose you are considering purchasing a hotel in
Colorado for an initial payment of $110,000. You predict that
cash flows for the first 2 years be $45,000 each year, $55,000
for the third year and $60,000 for the fourth year. You desire a
20% return on investment. Can this amount be realized?
Keystroke Display Comment
================================================================
[Reg] Clear registers
110000 [ChS] [CFo] -110,000.00 Initial cash outlay
45000 [CFj] 45,000.00
2 [Nj] 2.00 1st and 2nd cash flow
55000 [CFj] 55,000.00 3rd cash flow
60000 [CFj] 60,000.00 4th cash flow
20 [ I ] 20.00 Interest rate
[NPV] 19,513.89 Net Present Value
- 28 -
The NPV for the hotel is positive, thus the investment will yield
the desired result.
6.8 Internal Rate of Return
The internal rate of return is a discount rate which equates the
present value of the expected cash outlays with the present value
of expected cash income. It is the rate of return an investment
is expected to return.
Example: Calculate the Internal Rate of Return for the above
example.
Keystroke Display Comment
================================================================
[IRR] 28.60 Internal rate of return
The investment will yield a 28.6% return.
Example: An investment in a startup technology business is
projected to involve negative cash flows of $30,000, $50,000 and
$70,000 for the first three years, and finally a positive cash
flow of $180,000 for the fourth year. Calculate the internal
rate of return, the return on the investment.
Keystroke Display Comment
================================================================
[Reg] Clear registers
30000 [ChS] [CFo] -30,000.00 1st cash flow
50000 [ChS] [CFj] -50,000.00 2nd cash flow
70000 [ChS] [CFj] -70,000.00 3rd cash flow
180000 [CFj] 180,000.00 4th cash flow
[IRR] 10.89 IRR
The investment would yield a 10.89% return after 4 years.
7. Bond Calculations
7.1 Bond Yield
The [Price] and [YTM] functions calculate the price and yield to
maturity of a semi-annual coupon bond. Using these functions,
calculations are done using a par value of 100.
Example: If you are interested in purchasing an 8.5% semi-annual
coupon bond at 94 1/2. Determine the yield this bond will
produce if you purchase it on November 15, 1987 and it matures on
April 7, 1996.
- 29 -
Keystroke Display Comment
================================================================
[M.DY] Mon/Day/Yr format
8.5 [PMT] 8.50 Coupon rate
94.5 [PV] 94.50 Bond price
11.151987 [ENTER] 11.15 Purchase date
4.071996 [YTM] 9.46 Yield
The bond would yield 9.46%.
7.2 Bond Price
Example: Assume you desire a yield of 8.75% on a bond that
reaches maturity on August 4, 1998. If the bond is a 7.25%
Treasury bond, how much should you pay for the bond on October11,
1988?
Keystroke Display Comment
================================================================
[M.DY] Mon/Day/Yr format
7.25 [PMT] 7.25 Coupon rate
8.75 [ I ] 8.75 Desired yield
10.111988 [ENTER] 10.11 Purchase date
8.041998 [Price] 90.24 Compute price
You should pay $90.24.
8. Statistical Calculations
XACT-12C can perform common statistical calculations including
mean and standard deviation using it's built-in capabilities. In
addition, programs can be written to perform complex statistical
analysis.
8.1 Entering and Removing Numbers
The [S+] (Greek "sigma" character followed by a '+') function key
is used to enter a new number into the statistical registers.
XACT-12C can be used to perform statistical operations using both
one and two variables. When using one variable, that variable is
referred to as the X variable. With two variable analysis, the
second variable is referred to as the Y variable.
When entering single variable numbers, enter the number and then
press the [S+] function key. Continue this process until all
numbers have been entered.
With two variables, first key in the Y variable and press the
[ENTER] key, then enter the X variable and press the [S+] key.
- 30 -
When the [S+] function key is used, memory registers 1 through 6
will hold intermediate values. You can use the [Rcl] function
key to view these values, or to use them within a program. The
values contained in registers 1 through 6 are summarized below:
R1 contains the value N, the number of data values
or data pairs) entered thus far.
R2 contains the sum of the X values.
R3 contains the sum of the squares of the X values.
R4 contains the sum of the Y values.
R5 contains the sum of the squares of the Y values.
R6 contains the sum of the products of the X values
and the Y values.
To remove an incorrectly entered value, you can use the [S-]
function key. Simply re-enter the incorrect value and then press
the [S-] function key.
8.2 Statistical Mean
Example: Suppose you are a teacher with 5 students. Student's
scores on their last test were 80, 63, 77, 94, and 79. Find the
mean of the test results.
Keystroke Display Comment
================================================================
[S] Clear statistics
80 [S+] 1.00 1st score
63 [S+] 2.00 2nd score
77 [S+] 3.00 3rd score
94 [S+] 4.00 4th score
79 [S+] 5.00 5th score
[xbar] 78.60 Mean
The mean of the test scores is 78.6.
8.3 Statistical Weighted Mean
Data for statistical weighted mean calculations are entered
similarly to data for other 2 variable statistical calculations
except that the [x w] function key is used to compute the
weighted mean.
Example: Find the average cost per minute of your monthly long
distance calls if you were charged for the following: 3 minutes
for $0.35 per minute, 13 minutes for $0.70 per minute, 9 minutes
for $0.56 per minute, and 4 minutes for $0.98 per minute.
- 31 -
Keystroke Display Comment
================================================================
[S] Clear registers
.35 [ENTER] 0.35
3 [S+] 1.00 First charge
.70 [ENTER] 0.70
13 [S+] 2.00 Second charge
.56 [ENTER] 0.56
9 [S+] 3.00 Third charge
.98 [ENTER] 0.98
4 [S+] 4.00 Fourth charge
[x w] 0.66 Weighted mean
You paid an average of 66 cents per minute in long distance
charges.
8.4 Standard Deviation
XACT-12C can be used to calculate the standard deviation of both
x and y variables using the [S] function key.
Example: Assume a set of students test scores for math and
English tests are as follows:
Student Math English
===============================
1 59 64
2 66 69
3 88 82
4 70 51
Calculate the standard deviation for the students results.
Keystroke Display Comment
================================================================
[S] Clear registers
59 [ENTER] 64 [S+] 1.00 1st student
66 [ENTER] 69 [S+] 2.00 2nd student
88 [ENTER] 82 [S+] 3.00 3rd student
70 [ENTER] 51 [S+] 4.00 4th student
[S] 12.82 Math standard deviation
[x<>y] 12.37 English std. deviation
The standard deviation for the student's math scores was 12.82
and for the English scores was 12.37.
- 32 -
8.5 Linear Estimate
Using values entered for x and y variables, you can compute a
"best guess" for either variable, given a sample value for the
other one.
Example: Using the above data for student test scores, compute
an estimate for a student's English score given that the student
has a math score of 80. Compute the correlation coefficient for
this value.
Keystroke Display Comment
================================================================
80 [y,r] 78.87 Math score estimate
[x<>y] 0.62 Correlation Coefficient
9. Calendar Calculations
9.1 Days between Dates
XACT-12C can compute the number of days between 2 dates using the
[DDays] and future or past date given a number of days using the
[Date] function. These functions can be utilized in compound
interest calculations as well as bond price and yield
calculations.
Example: Compute the number of days between July 4, 1987 and
October 31, 1987.
Keystroke Display Comment
================================================================
7.041987 [ENTER] 7.04 First date
10.311987 10.311987 Second date
[DDays] 119.00 Days between dates
There are 119.00 days between these 2 dates.
XACT-12C can also perform date calculations using the
Day/Month/Year format. To use this format, press [d.my]. The
calculator will display D.MY on the right of the screen to remind
you that you're using this format. To return to Month/Day/Year
format, press [M.DY].
9.2 Date Calculations
Example: What will the date be 178 days from now if today is
July 19, 1988?.
- 33 -
Keystroke Display Comment
================================================================
[D.MY] Day/Mon/Yr format
19.071988 [ENTER] 19.07 First date
178 [Date] 13,1,1989 5 Future date
The date will be January 13, 1989. It will fall on a Friday.
(The last digit indicates the day of the week, i.e.
0=Sunday,1=Monday, etc.).
Example: On what day were you born if your birthday was August
27, 1958?
Keystroke Display Comment
================================================================
[M.DY] Mon/Day/Yr format
8.271958 [ENTER] 8.27
0 [Date] 8,27,1958 3 Wednesday
10. Programming
10.1 Introduction to Programming
Programming XACT-12C is a process whereby you "teach" the
calculator a series of keystrokes, similar to the way you would
normally enter the keystrokes if you were computing a problem
manually. In addition, you can have a program take different
actions in a program based upon values contained in registers.
For example, the program could take a different course of action
if the value contained in the X register is less-than-or-equal-to
the value in the Y register. This is known as "conditional
branching". Programming also allows you to repeat given
keystroke sequences a certain number of times. This is known as
"looping".
If you are interested in advanced programming features of
XACT-12C, we suggest you obtain a copy of the HP-12C Owner's
Handbook and Problem Solving Guide and optionally any of the
other manuals which were mentioned earlier in Chapter 1.2.
10.2 Entering a Program into XACT-12C
To begin entering a new program into XACT-12C, the calculator
must be placed in Program mode by pressing the [P/R] function
key. When in program mode, subsequent keystrokes are simply
stored in the calculator's internal memory. The [P/R] key toggles
between program and run modes.
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Keystroke Display Comment
================================================================
[P/R] 00- Program mode
[P/R] (as before) Run mode.
When first entering program mode, the display shows the value
00-. This represents the current program line number of the
program you are entering. Line 00- is special in that it always
represents the beginning of program memory. Let's enter a very
simple program:
Keystroke Display Comment
================================================================
[P/R] 00- Program mode
[Prgm] 00- Clear program memory
1 01- 1
0 02- 0
[ENTER] 03- 36
4 04- 4
[ + ] 05- 10
[P/R] Run mode
The program simply adds the numbers 10+4 and finishes. When
XACT-12C is in program mode, the numbers to the right of the
program line are a code which represents which key was pressed.
The first digit of the number indicates the row and the second
indicates the column of where the key is positioned on the
XACT-12C screen. If you think of all the keystrokes on the
calculator face as being in a table with 4 rows and 10 columns,
each key can be identified as being in a certain row and column.
For example the [ENTER] key is located in Row 3, Column 6. Thus
in instruction line 03- the display contains the value 36.
Likewise the [ + ] key is in row 4, column 10, so the display
shows 40.]
To run the program:
Keystroke Display Comment
================================================================
[R/S] 14.00 Program result
As a more practical example, we will write a program that
converts a nominal interest rate into an effective annual
interest rate. To use the program, enter the number of
compounding periods per year in memory 1, the nominal interest
rate in memory 2, and run the program by pressing [R/S].
Keystroke Display Comment
================================================================
[P/R] Switch to program mode
[Prgm] 00- Clear program
[Fin] 01- 42 34 Clear fin. registers.
[Rcl] 2 02- 45 2 Recall interest rate
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[Rcl] 1 03- 45 1 Recall compound interval
[ N ] 04- 11 Store in N register
[ / ] 05- 40 Divide
[ I ] 06- 12 Store int. rate per
compounding period
1 07- 1
0 08- 0
0 09- 0
[Chs] 10- 16
[ENTER] 11- 36
[PV] 12- 13 Set PV to -100
[FV] 13- 15 Compute FV
[ + ] 14- 10
[P/R] Return to Run mode
For example, assume you wanted to compute the effective rate of a
savings account that earned 6 7/8% compounded semi-annually.
Keystroke Display Comment
================================================================
7 [ENTER] 7.00
8 [ / ] 0.88
6 [ + ] 6.88
[Sto] 2 6.88 Nominal interest rate
2 [Sto] 1 2.00 Compounding interval
[R/S] 6.99 Effective Rate is 6.99%
10.3 Program Loops and Branches
XACT-12C can make "conditional tests" based upon values contained
in the X and Y registers. When running a program, these
functions will execute the next instruction in the program if the
condition is true, and skip over it if the condition is false.
The instructions are defined as
[x<=y] true if x less than or equal to y
[x=0] true if x equals 0
For example, you could execute a series of instructions within a
loop using the above conditional tests. The example below adds
the numbers 1 through 5 in a loop, stores the result in memory
register 1 and then finishes.
Keystroke Display Comment
================================================================
[P/R] Programming mode
[Prgm] 00- Clear program
0 01- 0
[Sto] 1 02- 44 1 Clear register 1
5 03- 5 Start with 5
[Sto] [ + ] 1 04- 44 40 1 Add to Memory 1
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1 05- 1 Decrement
[ - ] 06- 30
[x=0] 07- 43 35 Test for 0
[R/S] 08- 31 Done
[Gto] 04 08- 43 33 04
[P/R]
When the program is run, the resulting answer will be contained
in memory register 1.
11. Appendix
11.1 Error Conditions
When an error is encountered during operation, XACT-12C will
display the word "Error" in the calculator's display, followed by
a 1 digit error code. These error codes are defined below:
Error 0 - Invalid math operation. This error is encountered
when an operation attempted division by 0, a square root of a
negative number, or other invalid math operation.
Error 1 - Out-of-Bounds Storage register operation. This
happens if a storage register operation overflows the range of
the calculator.
Error 2 - Invalid Statistical operation. This happens if a
statistical operation cannot be performed or is out of range, for
instance taking the mean of 0 numbers.
Error 3 - IRR. This error happens if an IRR cannot be
performed or has ambiguous data.
Error 4 - Memory range overflow. This error occurs if an
attempt has been made to access an out-of-range memory location.
Error 5 - Invalid interest operation. This error occurs if
invalid or ambiguous input data was used to calculate a compound
interest result, for instance if all cash flows have the same
sign.
Error 6 - Invalid storage register. This error occurs if a
storage register is invalid, or if N or N20 when calculating NPV
or IRR.
Error 7 - IRR. The IRR calculation cannot be performed with
the given input data.
Error 8 - Invalid calendar calculation. A date is out of range
or in an ambiguous format.
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