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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. - 34 - 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 - 35 - [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 - 36 - 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. - 37 -