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From: [e-mail] (Andre Schoorl)
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Subject: comp.sys.hp48 FAQ : 1 of 4 - Common Questions
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Summary: Answers to Frequently Asked Questions about HP48 calculators
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Archive-name: hp/hp48-faq/part1
Last-modified: 4/14/2000
Version: 4.62
Posting-Frequency: Every 14 days or so

New in v4.62

  o  Added another alternate solution to Compact Data Storage problem

  o  Gave proper credit to Dave Hicks for his Q/A on RPN


-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

  HP48 Frequently Asked Questions List (FAQ)
  Andre Schoorl <[e-mail]>
  v4.62, 14 April 2000

  Answers to Frequently Asked Questions about HP48 calculators
  ______________________________________________________________________

  Table of Contents


  1. Introduction

     1.1 Overview
     1.2 This FAQ in Other Formats
     1.3 Translations of this FAQ

  2. Miscellaneous Questions

     2.1 I'm a novice, and I have some questions.  Where should I start?
     2.2 What Usenet Newsgroups are there for the HP48?
     2.3 What are some good sites for the HP48?
     2.4 Are there any good WWW links for HP48 stuff?
     2.5 Is there an HP48 IRC Channel?
     2.6 How can I search for a specific HP48 file?
     2.7 What are good places to buy HP48's and accessories?
     2.8 What happened to EduCalc?
     2.9 Are there any CD-ROMs with HP48 software?
     2.10 Where can I find HP conference videotapes?
     2.11 Are there any HP48 Emulators?
     2.12 How can I make a dump of my HP48 ROM?
     2.13 Is the HP48 Allowed on SATs, AP, or ACT Tests? (U.S.)
     2.14 What is the HP49G?
     2.15 How does the HP48 compare with other calculators?
     2.16 What is the Universal Font Library (UFL)?
     2.17 What are the best alternate editors?
     2.18 Are there any PC fonts for the HP48?
     2.19 Is the HP48 serial number available in memory?
     2.20 What is the format of the HP48 serial number?

  3. Questions about ROM versions

     3.1 What does the SX/GX have that the S/G doesn't?
     3.2 What is the difference between the HP48 G/GX and the HP48 S/SX?
     3.3 What is the HP48 G+?
     3.4 How can I tell what ROM revision I have?
     3.5 What bugs exist in the various versions of the HP48?
     3.6 What is new with the revision "J" ROM? (S/SX)
     3.7 What happened to ROM revisions G, H, I, O, and Q?
     3.8 Can I upgrade my HP48 S/SX?
     3.9 Can I upgrade my buggy GX to the latest ROM revision?
     3.10 What's the latest ROM version?
     3.11 Why would I buy a S/SX rather than a G/GX?

  4. Questions about the Operating System and Using the HP

     4.1 How do I find the checksum of an object?
     4.2 I typed RULES on my G/GX and got a crossword puzzle!
     4.3 Why does my HP48 occasionally "freeze" for a moment?
     4.4 What do I do if my HP48 locks up?
     4.5 My HP48 seems to take longer to turn on and off.
     4.6 What are all the different ON-KEY combinations?
     4.7 What are the different interactive self-tests?
     4.8 Why do I get an ESD error when I check my batteries with the self test?
     4.9 I can't account for some of the RAM in the HP48!
     4.10 What are the best methods for installing and removing libraries?
     4.11 How can I attach large libraries?
     4.12 What are those little numbers near the top of my screen?
     4.13 Can I use my HP48 as a remote control?
     4.14 Can the HP48 be used as a DTMF phone dialer?
     4.15 How can I run a program on warmstarts and/or power-up?
     4.16 I could speed up my HP-28S.  How can I speed up my HP48?
     4.17 What is the hidden directory and how do I access it?
     4.18 How can I recall one object from a memory archive?
     4.19 Are there any key combinations that aren't in the manual?
     4.20 How do I find out about commands not in the GX manual?
     4.21 How can one delete (or purge) an entire directory?
     4.22 How does binary wordsize affect my calculations?
     4.23 Can I add my own equations to HP's Equation Library?

  5. Questions about Math, Plotting, and Equations

     5.1 Why does (1/3)*3 equal 0.999999999999?
     5.2 Why does my HP say that 0 to the power of 0 equals 1?
     5.3 What is RPN?
     5.4 Why did HP use RPN in their calculators?
     5.5 Is there an alternative to calculating in RPN?
     5.6 Why do I get unexpected values when I add temperatures?
     5.7 How can I add my own units?  What's the 1_? unit for?
     5.8 I want `pi' to be a numeric value, not a symbol.
     5.9 What tricks are there for manipulating matrices?
     5.10 Can I make my HP graph any faster?
     5.11 How do I plot inequalities?
     5.12 How do I take the logarithm of a base other than 10 or e?
     5.13 How do I solve quadratic equations?
     5.14 Why do I get a complex answers for roots of negative numbers?
     5.15 Why doesn't '(-8)^(2/3)' give me the right answer (4)?
     5.16 How do I solve polynomials?
     5.17 How can I do statistics for grouped data?
     5.18 How do I generate a function table?

  6. Questions about cards, data transfers, batteries, and hardware

     6.1 My HP48 seems to making a high pitched noise.
     6.2 Can I upgrade my S or G to more than 32K ram?
     6.3 Can I add a lithium battery backup?
     6.4 How can I get/build a cable for my HP48?
     6.5 HP seems to offer two link kits with different prices.
     6.6 Is there any communications software available?
     6.7 Why doesn't the I/R port work farther than a few inches?
     6.8 Can my HP48 talk to my HP100LX via Infrared?
     6.9 Can I use my HP48 to communicate with IrDA devices?
     6.10 Can I print to a LaserJet printer with an HP48?
     6.11 I downloaded a program but all I get is "HPHP48-..."!
     6.12 What is the structure of HP48 ASCII headers?
     6.13 Why do Kermit transfers seem to get slower?
     6.14 Why does XRECV not work sometimes? (GX)
     6.15 Additional Tips on Transfers
     6.16 What do the funny symbols in this document mean?
     6.17 What are the pinouts for the HP48 serial connector?
     6.18 Is there any information on interfacing to the HP48?
     6.19 How can I transfer programs/data from my HP-28S to my HP48?
     6.20 Can I use rechargeable batteries with the HP48?
     6.21 How can I tell, from within a program, if the battery is low?
     6.22 I lost the information on my RAM Card when I changed the battery!
     6.23 Why do I get an "Invalid card data" error when I merge a RAM card?
     6.24 I've heard about other manufacturer's RAM cards.  Will they work?
     6.25 How does RAM card locking work?
     6.26 What are the advantages and disadvantages of covered ports? (GX)
     6.27 Why does the HP48 display flicker slightly?
     6.28 I broke the LCD screen - is there an easy way to get another?
     6.29 How can I protect my LCD?
     6.30 Is there a rigid (protective) case for the HP48?
     6.31 Can I use my Amateur Radio with my HP48?

  7. Questions about programs

     7.1 Where can I get programs and information for the HP48?
     7.2 What are the Goodies Disks and where do I get them?
     7.3 How do I get access to the HP Calculator BBS?
     7.4 What are files that end with ".zip", ".Z", ".gz", or ".bz2"?
     7.5 What is a "ship" file?
     7.6 What is the ASC format and how can I use it?
     7.7 What is the HYDE library, and how do I get rid of it?
     7.8 What is the Minehunt game, and how do I use it?

  8. Questions about programming and advanced user functions

     8.1 I've heard the names RPL, Saturn, STAR, GL etc...  What are they?
     8.2 Is there a C compiler for the HP48?
     8.3 Why do SysRPL programs run faster than UserRPL programs?
     8.4 What is a good reference for learning SysRPL and ML?
     8.5 Can I make my own libraries?  Can I split others?
     8.6 How do I know what library ID number to use for my program?
     8.7 What information is there on the internals of the HP48?
     8.8 Where can I get some programming development tools?
     8.9 I know UserRPL.  How do I get started in SysRPL?
     8.10 Are there any viruses for the HP48?
     8.11 How do I store fields of variable length effectively?
     8.12 What is "Vectored Enter", and how do I use it?
     8.13 What is "WSLOG"?
     8.14 What are SYSEVALs?
     8.15 What are some useful SYSEVALs?
     8.16 What are LIBEVALs?
     8.17 What are some useful LIBEVALs? (GX)
     8.18 What is the format of a GROB object?
     8.19 What is the AUR and what information does it contain?
     8.20 What is the syntax for INFORM, CHOOSE, and MSGBOX? (GX)
     8.21 How do I put checkfields in my INFORM menus?
     8.22 What is the syntax for the INPUT command?

  9. Appendix A: Various Useful Functions

     9.1 ASC Functions
     9.2 OBJFIX
     9.3 FIXIT
     9.4 LASTX
     9.5 Compact Data Storage
     9.6 HP82240B Printer Codes

  10. Appendix B: GX Specific Information

     10.1 What's new in the HP48 G/GX?
     10.2 Examples of INFORM, CHOOSE, and MSGBOX
     10.3 Some useful LIBEVALs

  11. Appendix C: Details of Bugs

     11.1 The EquationWriter Bug
     11.2 Rotation Rate to Angular Frequency Conversion Bug

  12. Appendix D: Hardware Additions

     12.1 How to Make a Serial Cable
     12.2 Using a modem with the HP48
     12.3 Additional Information on the HP48 and RS-232
     12.4 Using Non-HP RAM Cards
     12.5 Where can one obtain third party RAM cards?

  13. Appendix E: Where to get HP48 Programs

     13.1 Best Programs and Where to Get Them List
     13.2 Other Web / FTP Sites
     13.3 FTP by Electronic Mail
     13.4 Bulletin Boards with HP48 Programs
     13.5 HP Goodies Disks

  14. Contributors

  ______________________________________________________________________

  1.  Introduction

  This FAQ is maintained by Andre Schoorl <[e-mail]>

  It was previously maintained by Keith Maddock, and was originally
  compiled by Darryl Okahata.  Many thanks to both for their time and
  contributions!

  I rely on your input in order to keep this FAQ up to date.  If you
  have any suggestions or updates, feel free to mail them to me.  If you
  have a correction or suggestion to make, please include the name of a
  specific question rather than its number as the number is
  automatically generated and can change between versions.


  1.1.  Overview

  The purpose of this FAQ is to provide answers to commonly asked
  questions about the Hewlett Packard HP48 family of scientific
  calculators.  This list contains information which has not necessarily
  been verified, and is not guaranteed to be correct.  It has been
  compiled from various postings in the newsgroups comp.sys.hp48 and
  comp.sys.handhelds, as well as other sources.  In particular, some
  parts were taken from older HP48 SX "FAQ Lists".

  For some questions, there may be different answers for each calculator
  (G/GX vs. S/SX).  In this case S/SX specific information is preceeded
  by an "SX:" on the left margin of the first line of each S/SX specific
  paragraph.  G/GX information is denoted by a "GX:" in the same place.
  If a paragraph has no notation, then it is valid for all versions.


  1.2.  This FAQ in Other Formats

  This document was made using the SGML-Tools (Standard Generalized
  Markup Language) package and is available in ASCII, HTML, and
  PostScript versions.  All versions come from the same source, and are
  thus updated simultaneously.

  The URL for the HTML version is
  <http://www.engr.uvic.ca/~aschoorl/faq/>.  The other formats are also
  available here in separate zip files.

  The PostScript version is formatted for letter size paper, but it is
  also possible to create PostScript for legal size paper.  Furthermore,
  DVI, LaTeX, Lyx, Info, and RTF forms of the FAQ are also possible.
  Since it is impractical to provide all of these formats, the SGML
  source is available in case anyone wants to create one of these
  formats on their own.

  Text only versions of the FAQ will be posted to the newsgroup
  comp.sys.hp48 as needed (usually every two weeks).  Also, remember
  that all official FAQs (including this one) are mirrored at
  <ftp://rtfm.mit.edu/>.

  Furthermore, it is posted to comp.answers and news.answers.

  I will sign all text versions with PGP (Pretty Good Privacy) using the
  following key for authenticity, and provide MD5 Checksums for the
  remaining files.  You can get a copy of this public key from the
  keyserver at <http://pgpkeys.mit.edu/>, or through the URL above.


  Type Bits KeyID    Created    Expires    Algorithm       Use
  sec+ 1024 2CFAA0BB 1997-06-21 ---------- DSS             Sign and Encrypt
  sub  2048 F940E148 1997-06-21 ---------- Diffie-Hellman
  uid  Andre P. Schoorl <[e-mail]>


  Alternatively, you can download the FAQ at one the following
  locations:


     North America:

     o  <http://www.hpcalc.org/docs/faq/>

     Europe:

     o  <ftp://ftp.stud.fh-heilbronn.de/pub/systems/hp48/incoming/>

     o  <ftp://ftp.stud.fh-heilbronn.de/pub/systems/hp48/info/FAQ/>


  1.3.  Translations of this FAQ

  These translations may not be as up to date as the main FAQ, but
  should still be useful for international users who are more
  comfortable with their native language.


     Portugese:

     o  <http://members.tripod.com/~area48/> by Carlos Alberto Marangon

     Spanish:

     o  <http://www.alumnos.utfsm.cl/~aarrieta/hp48.html> by Alejandro
        Arrieta Rios and Guido Carvajal


  2.  Miscellaneous Questions

  2.1.  I'm a novice, and I have some questions.  Where should I start?

  Start by perusing the HP48 manuals.  You'd be amazed how many
  questions can be answered if you read the manuals.


     SX:
        Earlier HP48 S/SX manuals came in two volumes. The first volume
        dealt with operating instructions, and the second volume dealt
        with programming.  Later HP48 S/SX manuals combined these two
        volumes into one.

     GX:
        HP48 G/GX models come with a one-volume owners manual that
        covers all of the non-programming aspects of the calculator.  An
        Advanced User's Reference (AUR) is available that covers
        programming aspects.  It is highly recommended.  They also come
        with a Quick Start Guide, a guided tour of some of the HP48's
        capabilities.

  Also, look over the section "Answers to Common Questions", in Appendix
  A of the manual.  If you have a two-volume manual, it will be in
  volume II.


  2.2.  What Usenet Newsgroups are there for the HP48?


     comp.sys.hp48
        Primary HP48 newsgroup.

     comp.sys.handhelds
        Occasionally, HP48 information is posted to this newsgroup.

     comp.sources.hp48
        This newsgroup has been dead for years, but was once a moderated
        group for HP48 Programs.

     es.comp.sistemas.hp48
        Is a spanish newsgroup for the HP48.

  Articles posted to the newsgroup comp.sys.hp48 are archived at
  <ftp://wuarchive.wustl.edu/usenet/comp.sys.hp48/>.  Articles are
  archived by year and month, with a general index covering
  approximately the past two years.

  The AltaVista search engine at  <http://www.altavista.digital.com>
  also accesses these archives (for a Usenet search), and automatically
  uncompresses any relevant articles you may select.

  DejaNews  <http://www.dejanews.com/> is another fast Usenet
  archiver/searcher, with many extra features such as Author profile and
  article search.  The only drawback is that it strips attachments from
  posts (uuencode, MIME) to save space.

  Another good way to find HP48 posts is through one of the various
  search engines available on the web.  For example, Netscape, Lycos,
  and Magellan and others all seem to be able to find Usenet articles on
  the HP48.  The search may even find articles that have long since
  expired from your local news server!


  2.3.  What are some good sites for the HP48?

  Many HP48 programs can be found on the following FTP sites:

  o  <http://www.hpcalc.org/>

  o  <ftp://ftp.hp.com/pub/calculators/>

  o  <ftp://wuarchive.wustl.edu/systems/hp/hp48/>

     For a list of other HP48 FTP sites, see Appendix E-2.


  2.4.  Are there any good WWW links for HP48 stuff?

  Rather than list out a long list of HP48 related WWW resources, here
  is a single HP48 Page which contains links to other HP48 pages:

  o  <http://www.gmi.edu/~madd0118/hp48/>

  Another well maintained site is  <http://www.hpcalc.org/>.


  2.5.  Is there an HP48 IRC Channel?

  Yes, try connecting to an EFNet server and join channel #hp48.  Many
  of the most knowledgeable HP48 users frequent it, making it a nice
  place to get your questions answered.  There are even two IRC robots
  (hp48b and RPL) on the channel.  The following information will get
  you started:

  First, download an appropriate IRC client.  Collection of clients are
  available at  <http://www.irchelp.org> or <ftp://ftp.undernet.org/>

  Second, find a working EFNet server and join #hp48.  A list of servers
  is given at
  <http://www.irchelp.org/irchelp/networks/servers/efnet.html>


  2.6.  How can I search for a specific HP48 file?

  If you know the all or part of the filename of an HP48 program, you
  can use the proper Internet search services instead of bothering all
  the readers of the newsgroup.  The following server is especially
  good, it seems to find HP48 files from just about anywhere.


       <http://ftpsearch.ntnu.no/ftpsearch>


  2.7.  What are good places to buy HP48's and accessories?


     X-Philes CD-ROM:
        There is a CD-ROM called the X-Philes on the market that
        includes many HP48 files.  See the next question for more
        details.

     Office Max:


          Toll Free: [phone]


     Wholesale Products:
        This is another company on the web that sells HP handhelds,
        including the HP48.  Their address is
        <http://www.wholesaleproducts.com> or you can mail inquiries to
        <[e-mail]>


          The Mall At Wholesale Products
          400 West Cummings Park
          Suite 1725-122
          Woburn, MA 01801
          781-438-8622 (Telephone, 9 a.m. - 5 p.m. Boston time)
          781-438-8307 (FAX, 24 hours a day, 7 days a week, from anywhere)
          E-mail: [e-mail]


     Web:
        North America:

     o  <http://www.wholesaleadvantage.com/hpcalcs.html>

     o  <http://www.waterw.com/~jake-s/handyclc.htm>


     o  <http://www.dvtg.com/>

     o  <http://www.smi.com/>

     o  <http://www.tdsway.com/>

     o  <http://www.ramss.com/>

     o  <http://www.chotkeh.com/>

     o  <http://muffet.com/samsoncables/>

     o  <http://www.calculatorsinc.com/>

        Europe:

     o  <http://members.aol.com/weidatec/>

     o  <http://www.Digitalis.de/>

     o  <http://stolte-edv.com/>

     o  <http://home.t-online.de/home/FFFFF/>

     o  <http://www.bbm.e.se/>

     o  <http://www.geocities.com/Eureka/Enterprises/3190/>


     Others:


          Global Connections Incorporated (formerly Connection Point, Inc.)
          50 South River Street, Suite 105, Janesville, WI 53545
          Tel: [phone] or (608)-752-1537

          Oxford Educational Supplies (U.K.)
          Tel: [phone] (mail order)
          Notes: No shipping charge for within U.K.

          Spectrum Office Equipment
          22 Stokes Croft Bristol (U.K.).
          0117 9428278

          Best (Western U.S., used to be La Belles) 1-800-950-2378

          Calculators Inc., Minneapolis, MN, U.S. [phone]

          Carrington, [phone]

          J&R Music World - Computer World 1-800-221-8180

          Office Depot (U.S. and Canada)

          Service Merchandise (East Coast U.S.)


  2.8.  What happened to EduCalc?

  EduCalc, which had been one of the best sources for HP48's and
  accessories, went out of business on 31 December 1997.


  2.9.  Are there any CD-ROMs with HP48 software?

  Yes, there are a few CD-ROMs with HP48 software I know of:

     HP48 Archive CD:
        The most current set of files at  <http://www.hpcalc.org/> is
        always available on a custom burnt CD-R.  Details are at the
        same URL.

     X-Philes:
        The X-Philes is a CD-ROM made by Synchron Data that contains
        most HP48 programs to date.  All together the CD-ROM contains
        over 21,000 files and more than 620 MB of information, mostly
        zipped.

        The HP48 sections contain 3194 files and make up 38.5 MB of the
        total.  This includes all of the Goodies disks (aka Horn disks)
        1 through 10.

        There are also files for HP95, Psion, TI-82 and TI-85
        calculators, as well as information and programs on:

        Jokes, Star Trek, Sports, Midi, History, Strange files,
        Conspiracy, Law and Business, Internet & Networks, Atari, BBS-
        Systems, Hardware, Computers, 3D-Objects, Anarchy, Hacking,
        Movies, X-Files, Music, Magazines, Science, UFO and Aliens,
        Occult, Security & Privacy, Amiga, Cyberspace, Subcultures,
        Radio, Virus hunting, Survival, Phreaking, PC utilities, Game
        cheats and levels, and Programming.

        The CD comes with easy to use Windows software for browsing and
        searching for keywords.  This software contains an upload
        feature that allows you to transfer programs directly to your HP
        (or modem) using X-Modem.

        More information on obtaining the X-Philes CD-ROM is at:

        WWW:  <http://www.algonet.se/~synchron/>

        E-Mail: <[e-mail]>

        Regular Post:


          Synchron Data
          Tranbarsvagen 25:14
          372 38 Ronneby
          Sweden


     SHAREWARE Volume 1 for Hewlett-Packard:
        There is a CD-ROM by a German company called Yellow Computing
        named SHAREWARE Volume 1 for Hewlett-Packard.  It sells for DEM
        49.80 (U.S.$ 34.00), and is distributed from:


          Yellow Computing                Phone [phone]
          Computersysteme GmbH              Fax [phone]
          Postfach 1136
          D-74173 Bad Friedrichshall
          Germany

     This is the German company which offers PC <-> HP-48 transfer
     cables together with Windows software for transfering files (the
     "Transfile Win 48" package).

     The CD-ROM comes with a 16 page booklet in German and English which
     shows how to use the included Windows 3.1 transfer program (with
     program and catalogue files in both languages).

     It's sampled in Aug 95, pressed Oct 95 and contains about 85 MB of
     software for the HP48 SX/GX, 95LX, 100LX and 200LX; the Horn disks
     1 through 9, and about 710 additional HP-48 programs in the 9
     categories: Animation, Data, Games, Graphic, Programming, Maths,
     Memory, Science, Utility and Communications.  It also has about 200
     other unsorted, compressed HP48 files.  Decompression software is
     included.

     It's not an ISO CD-ROM, since it contains directories and files,
     whose names contain exclamation marks, hyphens and dollar signs.


     Handheld HP CD-ROM Library:
        This collection contains 13,611 files for a total of 314 MB of
        compressed software for HP Handhelds.  The principal groups of
        this collection are:


        1. HP28C/S (up to 2.5 Mb) Applications, Games, Utils, Docs.

        2. HP48S/SX (up to 48 Mb) Applications, Business, Chemistry,
           Communications, Emulators, Games, Graphics, Math, Physics,
           Programming, Sound, Time, Utils, Docs.

        3. HP48G/GX (up to 40 Mb) Applications, Business, Chemistry,
           Communications, Games, Graphics, Math, Physics, Programming,
           Sound, Time, Utils, Docs, Sys-RPL.

        4. HP38G (up to 2 Mb) Applets, Applet Development Kit, Docs.

        Platform files total 30 MB, additional documentation is 18 MB,
        various collections including the Horn disks and SysRPL
        collection total 106 MB, and finally 58 MB of information from
        HP groups around the world.

        For more information, orders, and pricing send e-mail to
        <[e-mail]>


     Ingenieur Professional CD ROM
        This is another German CD issued by Harald Kresin and Franz
        Lorenz.  It contains roughly 67 MB of HP Software.  Their web
        page is <http://home.t-online.de/home/05713201317> and their e-
        mail is <[e-mail];

        Their address is


          Franz Lorenz
          Pocketcomputer & Zubehoer
          Bruchstr. 51, D-32423 Minden Germany


  2.10.  Where can I find HP conference videotapes?

  Jake Schwartz maintains a list of videotapes of HP handhelds meetings
  / demos / conferences going back as far as 1986 and the intro of the
  HP18C.  They are available at relatively low cost to anyone who is
  interested.  The URL is <http://www.waterw.com/~jake-s/video.htm>.


  2.11.  Are there any HP48 Emulators?

  A fully functional HP48 emulator by Eddie Dost called "x48" is
  available.  It runs in X-Windows on any Unix based operating system
  like Linux or Solaris.  However, it requires a ROM dump of an HP48 to
  run.  Of course, due to copyright laws such a ROM dump cannot be
  distributed with the x48 package.

  Therefore, you must be the proud owner of an HP48 (S/SX or G/GX) in
  order to create your own ROM dump.  The emulator will look and act
  either like a S/SX or a G/GX, depending on what type of ROM dump you
  give it.  Further instructions are contained in the x48 package
  itself.  The latest version of x48 is available at
  <http://www.hpcalc.org/pc/emulators/>

  There is also a freeware emulator for Windows called Emu48.  It is
  written by Sebastien Carlier, and runs under either Windows 95 or NT.
  It offers many exciting features, including fast speed, saving of
  memory, direct loading of files onto the stack, a greatly customizable
  interface, and support for ports through 33.  It supports both S/SX
  and G/GX ROM dumps, and comes with a "RomDump Wizard" to help you
  create one.

  The binaries and full C++ source code, distributed under the GNU
  Public License, as well as more information, are available at
  <http://www.epita.fr:8000/~sebc/Emu48/>.  There are also a series of
  "Unofficial Service Packs" available at
  <http://privat.swol.de/ChristophGiesselink/>.

  An emulator for the HP38, based on Emu48 has also been created.  It is
  available at  <http://www.epita.fr/~avenar_j/hp/38.html>

  There is also an HP48 S/SX/G/GX Emulator for Amiga computers called
  Alcuin.  See  <http://www.cis.tu-
  graz.ac.at/home/schupfer/Alcuin/index.html> for more information.


  2.12.  How can I make a dump of my HP48 ROM?

  Emulators for the HP48 generally require an image of your HP48's
  internal ROM, also known as a "ROM Dump".  Currently the best program
  to make a dump of your ROM is ROMDump Wizard by Christoph Giesselink.
  It is available at  <http://privat.swol.de/ChristophGiesselink/>


  2.13.  Is the HP48 Allowed on SATs, AP, or ACT Tests? (U.S.)

  From: Jack Levy

  The S/SX/G/GX are allowed on the SAT's.  The S/SX/G/GX are allowed on
  the SAT II Math IIc test, but no calculators are allowed on any of the
  others.  The S/SX/G/GX are allowed on the AP Calculus exam.  However,
  only the S/SX are allowed on the AP Chem and AP Physics exams because
  the G/GX has the built in equation library.

  Update from: Sandler Rubin


  As of 1996, HP 48G calculators are allowed on the physics and
  chemistry APs, but only for the free response section.  All
  calculators are now banned on the multiple choice sections on the
  physics and chemistry APs.  As for calculus, the HP 48G is allowed on
  one half of the multiple choice and all of the free response.  The
  other half of the multiple choice on the calculus test must be
  completed without any calculator.

  These changes have occurred because the AP tests are now more
  conceptual and depend less on pure "number-crunching".  In the free
  response sections of the chemistry and physics tests, lists of
  important physics equations are include for student use which
  basically make the HP 48G EqLib redundant.

  Update from: John Goerzen

  After a lot of discussion with Candance Noble <[e-mail]> of ACT,
  they changed their policy to allow it only if the IR port is covered
  with opaque tape.  Their response follows:

  This notice is in response to questions ACT has received about
  acceptable calculators.  Please pass this clarification on to others.

  Effective Fall 1996, examinees may use calculators on the ACT
  Assessment and PLAN Mathematics Tests.  Students taking the ACT
  Assessment should review page 3 of Registering for the ACT Assessment.
  Students taking PLAN should review page 4 of the Planning Guide for
  Students and Parents.  All makes and models of calculators are
  acceptable -- including programmable calculators and hinged
  calculators with mathematical formulas printed by the manufacturer on
  the inside flap -- provided the calculator does not have any of the
  unacceptable features specified in the ACT publications noted above
  and further clarified below.  Examinees using unacceptable calculators
  will be dismissed from testing.

  The following information is provided to help students select an
  acceptable calculator if they choose to use one on the ACT Assessment
  or PLAN Mathematics Test.


     POCKET ORGANIZERS, HANDHELD OR LAPTOP COMPUTERS
        All such devices are prohibited.


     ELECTRONIC WRITING PADS/PEN INPUT DEVICES
        Such models are readily recognizable due to the pen or stylus
        used to input data.  All such devices are prohibited.


        The term QWERTY derives from the first six letter keys (left to
        right) of the top row of typewriters, personal computers, most
        handheld and laptop computers, pocket organizers, and
        specialized calculators.  All models with QWERTY keyboards are
        prohibited.


     PAPER TAPE
        If a calculator has a feature that provides paper output, the
        paper must be removed to make the calculator acceptable.


     NOISE
        Calculators that have a "talking" or audio feature are
        acceptable in a group testing situation only if the sound
        feature has been turned off.
     WIRELESS COMMUNICATION
        Calculators that can communicate (transfer data or information)
        wirelessly with other calculators can be recognized by the
        "window" or infrared data port on the top edge of the
        calculator, similar to one on a television remote control.  Such
        calculators are acceptable only if the wireless transfer
        capability is disabled by placing opaque material (such as
        masking tape) over the infrared data port.


     POWER CORD
        If a calculator can run on either battery or electrical cord,
        the electrical cord must be removed to make the calculator
        acceptable.


  2.14.  What is the HP49G?

  On May 21st, 1999, at the OpenHP Conference in Paris, France, Hewlett
  Packard announced the HP49G graphic calculator. The following
  information comes from Jean-Yves Avenard of HP's ACO (Australian
  Calculator Operation).


     Hardware

     o  512KB of RAM

     o  2MB of flash memory (1MB used for upgradable ROM, 1MB available
        to user)

     o  4MHz Saturn CPU

     o  131x64 pixel screen (black instead of blue, so higher contrast)

     o  51-key keyboard with tactile rubber keys


     o  This is not the same type of keyboard as the HP48 has but it is
        still an HP quality keyboard. Rubber keys don't always mean bad
        quality, as there are a lot of mechanical parts to make a
        keyboard.

     o  The feeling is extremely similar to the HP48 keyboard. Do you
        really think that HP could let a new product go out of its doors
        with a keyboard that will break after 6 months?


     o  New keyboard layout - a user friendly keyboard that incorporates
        the strengths of the existing RPN keyboard layout and the more
        familiar algebraic style keyboard layouts on the HP 38G, TI-83
        and TI-89.

     o  Metallic blue case with a translucent blue-tint slide-on cover.
        You can put it in the HP48's case if you prefer a soft case.

     o  No IR, but an HP49<->HP49 cable is provided (adapter included
        for connection to HP48). There were problems in some countries
        with some teachers fearing the HP48 would be used to cheat
        because of the IR port.

     o  RS-232 serial port with Kermit (binary, ASCII) and Xmodem (128
        checksum, 1K, 1K CRC) running at 9600 bps (15360 bps internally,
        but no PCs support that speed).

     o  Any unit may be directly connected to a data-logger, overhead
        projector, a personal computer or another HP 48G Series or HP
        49G graphing calculator.

     o  The hardware is not expandable, but the ROM can be software-
        upgraded and there is plenty of memory, so this should not be a
        problem.


     Memory Management

     o  Even though the Saturn can only access 512K of memory, a new
        bank switching routine is used, in addition to absolute
        addresses, making it much faster.

     o  The user sees three ports of memory: Internal System RAM (256KB,
        port 0), Extended RAM (256KB, port 1), and Flash User ROM (1MB,
        port 2).

     o  The system will manage how to copy your files for you, so there
        is no need to get lost in a bank.


     Software

     o  Step-by-step solving option that enables you to learn how to get
        the right answer numerically or symbolically.

     o  The most complete built-in Computer Algebra System (CAS)
        currently available on a calculator for fast, advanced symbolic
        manipulation and solving.


     o  Imagine an HP48 with Erable and ALG48 plus everything that is
        missing. Now speed it up so it can compete (and be faster) than
        anything else on the calculator market. That's the HP49's CAS.


     o  Inferential and Descriptive Statistics (suitable for Advanced
        Placement and College/University level statistics).

     o  A fast, flexible and intelligent Editor for isolating, editing,
        manipulating and evaluating text, equations, expressions, sub-
        expressions, programs and graphs.

     o  Input and Output Customization - choose between "textbook" form
        (pretty print), algebraic and RPN input and "textbook" and
        algebraic output in various font styles and sizes.


     o  When you first boot the machine, it's an algebraic machine.  If
        you don't like algebraic mode, simply press Mode, select "RPN"
        and that's it. You're back to the HP48 Reverse Polish Notation
        mode forever and ever (at least until you clear the memory or
        manually switch back to algebraic). It works EXACTLY like the
        HP48, but faster.


     o  Between 10 and 100 times faster than the existing HP 48G Series


     o  The OS has been completely rewritten, mainly in assembly
        language, so nearly everything that was slow on the HP48 works
        faster, including input forms, choose boxes, stack display,
        command line, file manager, etc. When I say faster, I mean MUCH
        faster. The HP49 is even faster than an HP48 with the MetaKernel
        running in it.


     o  There is no longer a built-in equation library but the constants
        library remains.

     o  Do you think the 4MHz CPU is slow? The 3D real-time plotter can
        draw 6 frames (for a 14*14 points matrix) per second... It's
        faster than any current competitors! You can rotate in real time
        over the X axis, Y axis and even the Z axis.


     Programming

     o  Provides four programming languages:


        1. HP Basic: like a hybrid between RPL and Basic. This does not
           have GOTO and cannot really be called Basic, as it looks like
           the HP38G's programming language. Example code:


             FOR(i,1,100)
                 DISP(i,1);
                 IF I+1-5==50 THEN DISP("Hello World",2) ELSE DISP("I'm off",2) END
             STEP(1)


        2. User RPL: Just like the HP48's built-in language. To reuse a
           User RPL program from an HP48, send it to the 49 using ASCII
           Kermit.

        3. System RPL: Development software, including disassembler,
           built into ROM but not supported.

        4. Assembly language: Development software, including
           disassembler, built into ROM but not supported


     o  Grayscale support (in ASM as well as System RPL). All System RPL
        graphic routines work on grayscale graphics.

     o  Vectorized Interrupt System (add your own interrupt handler)

     o  To run an HP48 application on the HP49, just recompile it. It
        will probably run faster, too, especially if it uses the GUI.

     o  Entry points have moved to make the ROM easier to maintain, but
        programs will still be compatible at the source code level.

  The HP49 is the most powerful calculator ever announced at any time.
  It works in two ways: one fully compatible with the HP48 series,
  including RPN but faster, and the other algebraic, easy for users of
  other calculator brands to learn to use.

  Although you may not agree with some of the specifications above,
  please wait until you touch it before complaining. After all, the HP49
  was developed by HP48 users and tested by HP48 users!

  For more information, visit the HP Calculator Archive at
  <http://www.hpcalc.org/>

  2.15.  How does the HP48 compare with other calculators?

  From: Chin-Yu Hsu <[e-mail]>

  What are the differences between the HP48 and the TI?

  Before listing the differences, I wish to let you know that the HP48
  has much more functionality than the TI's. However, these additional
  functions are usually of no help in high school than the TI. Instead,
  they are only helpful in college depending on the course you take. The
  TI is probably a better choice on tests in high school since it is
  easier to use (to most people) and does calculations faster (because
  it offers speed at the expense of the higher precision of the HP48).
  Please note that the HP also offers the HP38 which is more comparable
  to a TI-82.

  Also, you should realize that if you want support for the graphing
  calculator, the HP48 is the one to get. Although you can get support
  from Texas Instrument (by phone and by web), and also by teachers in
  school, you can get support for the HP48 from a larger group in the
  world. There are far more web sites related to the HP48 than to the TI
  graphing calculators. Also, the HP48 has its own newsgroup and its own
  IRC channel (usually up 24 hours a day and maintained by a bot that
  can send you programs at your request).  Please note that although the
  calculation and graphing capabilities may not be available for a
  particular calculator, you can usually download a program that extends
  such a capability to it.

  If you find that part of the information below is incorrect, please
  tell me about it. You may need to provide additional proof, if I am
  unable to confirm it.  Any additional information on the TI-92 is
  helpful because much about it is still a mystery.


     General Differences:


           Calculator            HP38     HP48(2)  TI-82(3)    TI-85      TI-92

           List Price(4)         $109   $135/$265    $125       $135       $250

           Available Mem.(5)     32KB    32/128KB   28.2KB     28.2KB     70.0KB

           Batteries Req.(6)     3AAA      3AAA     4AAA+1     4AAA+1     4AA+1

           Plug-in Cards          No      Yes(7)      No         No      Yes (Plus)

           Infrared Transmit.     Yes     Yes(8)      No         No          No

           Wire Transmit.         Yes      Yes       Yes        Yes         Yes

           Cal-to-PC trans(9)     Yes      Yes       Yes        Yes         Yes

           Overhead display       Yes     Yes(10)    Yes        Yes         Yes

           CBL support(11)        No        No*      Yes        Yes         Yes

           QWERTY keys(12)        No        No*       No         No         Yes

           Screen capture         Yes      Yes     via link   via link    via link

           Screen Resolution   131x64    131x64     96x62      128x64     240x128

           Character Display    22x8      22x8      16x8        21x8      ?????


     Miscellaneous Functions:


           Calculator            HP38     HP48(2)  TI-82(3)    TI-85      TI-92

           Simple Eq. Solver      Yes      Yes        No        Yes         Yes

           Simult. Eq. Solver    ?????     Yes        No        Yes         Yes

           Poly. Root Finder   No limit  No limit     No     30th order     Yes

           # of matrices          10     No limit      5      No limit    No limit

           max matrix size(12) No limit  125x125    15x15      30x30       99x999


     Graphing Functions:


           Calculator            HP38     HP48(2)  TI-82(3)    TI-85      TI-92

           Simultaneous Graph  Up to 10  No limit  Up to 10   Up to 99   Up to 99

           Zoom features          14        15        13         15       ?????

           Graph Tracing          Yes      Yes       Yes        Yes         Yes

           Fnc. Value Tables      Yes       No       Yes         No         Yes

           Parametric Graphs      Yes      Yes       Yes        Yes         Yes

           Polar Graphs           Yes      Yes       Yes        Yes         Yes

           Recur. Seq. Graphs     Yes      Yes       Yes        Yes         Yes

           Diff. Graphs           No       Yes        No         No          No

           Conic Graphs           No       Yes        No         No          No

           3-D graphs             No     7 types      No         No         Yes

           Area under Curve       No       Yes       Yes        Yes         Yes

           Extremum               Yes      Yes       Yes        Yes         Yes

           Roots                  Yes      Yes       Yes        Yes         Yes

           Slopes                 Yes      Yes       Yes        Yes         Yes

           Tangent Lines          No       Yes        No         No         ???


     Statistical Functions:


      Calculator            HP38     HP48(2)  TI-82(3)    TI-85      TI-92

      Scatter Graphs         Yes      Yes       Yes        Yes         Yes

      X-Y line Graphs        No        No        No         No         Yes

      Box-Whisker Plots      Yes       No       Yes         No         Yes

      Histogram Plots        Yes      Yes       Yes        Yes         Yes

      Regression Graphs      No       Yes       Yes        Yes         Yes

      Bar Graphs             Yes      Yes       Yes        Yes         Yes

      Truth Graphs           Yes      Yes        No         No          No


  Notes:


  1. In the specifications, "no limit" usually means that it is limited
     by memory only.

  2. There are five different HP48 calculators. There are the HP48S,
     HP48SX, HP48G, HP48G+, and HP48GX.  The S and SX models are older
     models, and no one would be getting them anymore since the G, G+
     and then GX offer all the same features, but with additional
     enhancements to make the features easier to use.  The G, G+, and GX
     are also 40% faster than the S and SX models.  The difference
     between the G and the GX is that the G has 32K of RAM, and no
     expandability, while the GX has 128K of RAM and the ability to have
     two additional plug in cards.  The G+ is in between, having 128K of
     RAM but no expandability.

  3. There is a new version of the TI-82, called the TI-83 which should
     be available soon. It offers all the features of the TI-82, except
     it has additional statistics and financial functions, as well as
     displaying a table and a graph side by side. Please note that this
     feature is not available on the HP48, but is available on the HP38.
     Also, the TI-83 has an equation solver like the HPs.

  4. Cost for HP calculators does not include cables because they can
     transfer data via infrared. The price for TI's include the cables
     for linking one TI to another. Also, the HP48G's list price is
     $135.00, while the HP48GX's list price is $265.00.

  5. The available memory listed for the HPs are slightly lower than the
     given values. The available memory for the HP48G is only 32 K. The
     HP48GX has 128K of available RAM, and is expandable to 4.5 megs!

  6. The batteries used by these calculators are AAA batteries.
     Rechargeable batteries are not recommended because they have a much
     lower life span than alkaline batteries. The TI's require an
     additional CR1616 battery to retain their memory power. The HP's do
     not need this additional battery, but once you take out the AAA
     batteries, you have about 3 minutes to replace them with new ones
     before it loses its memory. The RAM cards for the HP48GX requires
     an CR1616 battery, however, if you plan to store it outside of the
     HP.

  7. Only the HP48GX support plug-in cards. The HP48G doesn't.

  8. If you are thinking of getting the HP's to cheat on tests because
     of the infrared capability, forget about it. The infrared receivers
     on the HP's only have a maximum range of THREE inches (The HP's
     transmitter has a longer range, up to several feet, but that will
     not help at all unless you are using it as a remote control to
     watch TV, or you are sending to an infrared device connected to an
     AC power source, such as the HP LaserJet 5 printers).

  9. The Calculator to PC (or MAC) requires additional cable and
     software. For the HP, you only need to get the cable, which can be
     made from standard computer parts (a DB-9 and CD cable totaling
     about $15). No additional software is needed because you can use
     any communications program of your choice.  For the TI, you can
     either need to purchase a proprietary software and cable for about
     $60 to $80 at stores or you can download the software free at TI's
     web site, and try to make your own cable.  The same type of package
     is available from HP, but offers programming tools and debuggers,
     and costs about the same price.

  10.
     The overhead display unit for overhead projectors is available only
     for the HP48GX because the HP48G does not have the available
     extension slot to install the necessary interface card.

  11.
     The CBL stands for Computer Based Laboratory. It is created by TI,
     so it is not available on the HP of course. It simply allows you to
     collect data from different sources (sounds, temperature) at set
     intervals and can be analyzed on the calculator. The CBL unit's
     list price is approximately $225. Please note that there is a
     similar device for the HP-48, called the ADCM-48 which is a A-to-D
     converter and I/O interface that can read from four analog and four
     digital inputs.

  12.
     Please note that calculators with QWERTY keys are not allowed on
     the SAT exams.  The HP calculators do not have QWERTY type
     keyboards, but you can connect it to your computer and have the
     keys from your computer echo on to the HP calculator after
     installing a simple freeware program such as those found in
     <http://www.engr.uvic.ca/~aschoorl/archive/as-comm.zip>.

  13.
     The maximum matrix size on the HP48G is only 42x42. The maximum
     matrix size on the HP48GX is 85x85, but it can be expanded to
     125x125 with the addition of an extra RAM card.

  14.
     The TI-92 manual states lists can be up to 999 elements, and data
     can be arranged in 99 columns of 999 elements each.

  From: Bernard Parisse


  o  Overhead display: there are special models of the TI92 to do this,
     standard models give bad results

  o  Memory: The TI92-II model has 198K memory (price in France 1890 FF
     instead of 1390 FF)

  o  Processor: Modified 68010 at 10MHz

  o  Cabri-Geometre is very slow on the TI, the teachers I met at my
     lecture told me that they never use Cabri on the TI.

  o  Numeric computations: The HP clearly beats the TI, especially in
     linear algebra (factorization of matrices,
     eigenvalues/eigenvectors, etc...)
  o  Symbolic computations: The TI clearly beats the HP... without
     addition of any math programs.  Hence I compared the TI adding the
     best programs available on the net (i.e.  ntheory (10K) for number
     theory, odeproj for ordinary differential equations (40K), that was
     all since I had only a 70K TI92) with my HP loaded with Alg48 and
     Erable.  The main advantage of the TI92 is speed (about 5-10 times
     faster than Erable, 1-2 times faster than Alg48).  The main
     drawback on the HP48 side is the lack of a limit instruction.  Some
     features of Alg48 and Erable are not provided by the TI92:

  o  Factorization of integers (limited to factors less than or equal to
     65520 on the TI92, integers may not have more than 614 digits on
     the TI92) and of polynomials (e.g. the expanded form of:


       (x^4+x^3+1)*(x^4+x+1)


  is not factored on the TI92).

  o  Integration: the Risch algorithm is not implemented in the TI, e.g.
     it can not find the antiderivative of


       (1+2x^2)*exp(x^2)


  o  Taylor series: This feature is probably implemented like in the
     HP48 ROM, hence the TI can not solve series(sin(x)/(exp(x)-1)) at
     x=0 for order greater than 4.

  o  Eigenvalues/Eigenvectors/Jordanisation of matrices

  o  Systems of polynomials equations (Groebner bases)

  o  Ordinary differential equations are only solved with programs like
     odeproj, no support for Laplace or inverse Laplace transform

  o  A lot of internal programs are not accessible to the end-user on
     the TI92, as the source code of Alg48 and Erable is freely
     available.

  o  Programming: Assembler is now available on the TI, but there is no
     counterpart to SysRPL and the build-in language is comparable to a
     shell-script langage (with some limitations e.g. for usage of
     programs in functions)


  2.16.  What is the Universal Font Library (UFL)?

  The Universal Font Library, or UFL for short, is a set of libraries
  designed to help reduce the overhead of replacement fonts between a
  number of major HP48 programs.  The basic idea is instead of each
  program containing its own replacement font(s), the fonts are stored
  in a cetral library to save room.  In addition, the UFL comes with a
  Font Maintenance Library (FMnt).

  If you use some of the programs in the Best Programs List, you may
  find you need a particular UFL library installed in order to use the
  program.  The UFL is maintained by Andre Schoorl and is distributed
  under the GNU General Public License.  For more information and to
  obtain the UFL package, see <http://www.engr.uvic.ca/~aschoorl/ufl/>.
  2.17.  What are the best alternate editors?

  If you like a smaller font, I would recommend TED by Mika Heiskanen,
  or MiniWriter by Jean-Yves Avenard.  Both use FNT1 from the Universal
  Font Library (UFL) to allow font customization and to save space.

  MiniWriter is very small and fast, and has cut, copy, paste, and
  search features.  It is available at http://www.epita.fr/~avenar_j/

  TED has slightly more features, such as a character map, but as a
  result is larger.  TED is based on ED, which is the editor that comes
  with the Jazz library.  The latest version is available at
  <http://www.engr.uvic.ca/~aschoorl/>.

  If you prefer the medium font, I would recommend HP-Writer by Paquot
  Christophe.  It's quite small, fast, and uses FNT2 from the UFL.  Its
  features include cut, copy, and paste, as well as a macro key and
  built in User RPL key support.  However, it only works on G/GX.  The
  current version is available at
  <http://www.geocities.com/SiliconValley/Lab/1930/>.

  Other editors include StringWriter, also by Jean-Yves Avenard, which
  is a very complete and full featured library.  EDEN, by HPFox, is
  another popular editor in France.  Another is QED, which was
  originally written by Lutz Vieweg but is now maintained by Rick
  Grevelle.


  2.18.  Are there any PC fonts for the HP48?

  Yes, there are several fonts on the Goodies Disks (see the Appendix),
  as well as some TrueType fonts available at
  <http://www.hpcalc.org/pc/misc/>


  2.19.  Is the HP48 serial number available in memory?

  No.  There is no electronic version of the HP48 serial number.  This
  was apparently considered by the design team, but it was determined
  that the costs would greatly outweigh the benefits.


  2.20.  What is the format of the HP48 serial number?

  The HP48 serial number is printed on the back of the HP48, just above
  the battery compartment.  There are two different serial number
  formats.  The older format was used when the HP48 was first introduced
  and continued through the first part of 1997.  The newer format has
  been used on HP palmtops since about 1993 and was started on the HP
  calculators in the first part of 1997.

  The new serial numbers are in this format:


       ccywwnnnnn


     cc Place of manufacture (new two-letter code)

        The known codes are:


     o  SG = Singapore

     o  ID = Indonesia

     o  MY = Malaysia

     y  Year of manufacture.  This represents the last digit of the
        year.  A 7 would mean 1997.

     ww Week of manufacture (01-53).

     nnnnn
        The unit number for that week. (first unit on Monday is 00001)

  For example, if your serial number were SG72706543, the unit was the
  6543rd unit manufactured in Singapore during the 27th week of 1997.

  The old serial numbers are in this format:


       yywwMnnnnn


     yy The year the unit was made (add 1960 to this value)

     ww Week of manufacture (01-53).

     M  The manufacturing location (A for America, S for Singapore)

     nnnnn
        The unit number for that week.  (first unit on Monday is 00001)

  For example, if your serial number were 3321S07509, the unit was the
  7,509th unit manufactured in Singapore during the 21st week of 1993.


  3.  Questions about ROM versions

  3.1.  What does the SX/GX have that the S/G doesn't?


     SX:
        The HP48 S is the same as the HP48 SX except that the HP48 S
        does not have the two expansion slots of the HP48 SX.  This
        means that the HP48 S cannot be expanded and can only access 32K
        of memory, versus 288K for the HP48 SX (two 128K RAM cards).
        (Actually, there are third-party RAM cards that contain 256K or
        512K on a single card -- this memory is accessed via a bank-
        switching mechanism.)


     GX:
        The HP48 G is the same as the GX except for two differences.
        The GX has the 2 expansion ports, and also has 128K RAM built
        in, whereas the G only has 32K.

        If you plan on heavily using your calculator, you will probably
        find that 32K is not enough memory.  In fact, some of the best
        HP48 Programs will not even fit in this memory!


  3.2.  What is the difference between the HP48 G/GX and the HP48 S/SX?

  The HP48 G/GX calculators are, basically, slightly faster (by 40%)
  versions of the HP48 S and HP48 SX calculators, with more features,
  such as 3D-plotting and a new forms-based interface.  Much of the HP
  Solve Equation Library card is now built-in.  See Appendix B-1 for a
  detailed list of GX features.

  Note, however, that the HP48 G/GX is different from the HP48 S/SX in a
  number of significant areas:


  1. The HP48 GX comes with 128KB RAM, as opposed to 32KB RAM in the
     HP48 SX.  The HP48 G still has 32KB RAM, however.  The HP48 G/GX
     also has twice the ROM (512K), compared the HP48 S/SX (256K).

  2. Much of the HP48 G/GX internals have changed, compared with the
     HP48 S/SX.  Unfortunately, this means that many programs written in
     assembly language or System RPL won't work on the HP48 G/GX.  This
     is especially true of any program that tried to access the display
     memory directly.

  3. The HP48 G/GX CPU runs at 4 MHz, instead of the 2 MHz used with the
     HP48 S/SX CPUs.  However, due to various overheads (memory bank
     switching, etc.), the speed increase between the S/SX and G/GX is
     less than 2 times.  G/GX throughput is approximately 40% faster.

  4. Slot 2 of the HP48 GX can access up to 32 ports (ports 2-33) by
     bank switching.  Each port is 128KB, for a maximum total of 4 MB in
     slot 2.


  3.3.  What is the HP48 G+?

  The HP48 G+ was announced 30 March 1998.  It is essentially a HP48 G
  with more memory - it has 128K of memory instead of 32K.  All G+
  machines have revision R ROMs.

  There is no change to other aspects of the calculator model offerings.
  Specifically, it looks like HP has added to the HP48 family without
  withdrawing anything.  The G, G+, and GX will all continue to be sold.

  The press release for the HP48 G+ is at:
  <http://www.hp.com/pressrel/mar98/30mar98.htm>


  3.4.  How can I tell what ROM revision I have?


     GX:
        Type the command "VERSION".  Note that this command is not part
        of any key or menu, and so you must spell it out.

        Type #30794h SYSEVAL.  It returns a string, "HPHP48-x", where x
        is your ROM revision.  This works for both SX and GX.

     SX:

        1. Turn the calculator on (press ON and then release).

        2. Press ON again, and hold it down.

        3. While holding down the ON key, press and hold down the "D"
           key (the fourth white key in the top row).


        4. While holding down the "D" key, release the ON key.

        5. Release the "D" key.  The display should be blank, with the
           exception of three vertical lines (one down the centre, and
           one down each of the right and left sides).

        6. Press the backspace key (it says DROP and CLR over it).  A
           meaningless string of digits should appear in the top line of
           the display (mine says "705D9:1B8DA178E5A111B6" -- yours may
           be different).

        7. Press and hold down the EVAL key.  It should say something
           like the following, where the ? is an uppercase letter
           indicating the ROM version:


             Version HP48-?
             Copyright HP 1989


        8. Release the EVAL key.  Hold down ON and hit "C" (the third
           white key in the top row.  This is a general reset operation
           that returns the calculator to normal from the diagnostic
           stuff (which is where ON-D puts you).


  3.5.  What bugs exist in the various versions of the HP48?


     Rom: A

     o  DEFINE rounds numbers in user-defined functions if STD is not
        the current display mode.

     o  KGET on a zero length file from another machine will cause the
        calculator memory to be cleared.

     o  NXEQ from the Graphics Environment with flag -3 set (SYM off in
        Modes) can overwrite the current equation with a number.

     o  Displaying the clock in 24-hour format causes the one-digits for
        minutes to be incorrect in the alarm catalog.

     Roms: A-C

     o  INV returns an incorrect result if used on an 8x8 or larger
        matrix.  To get around this problem, divide the identity matrix
        with the matrix to invert.

     Roms: A-D

     o  Entering a symbolic complex number in polar form like (A,<B)
        (where < is really the funny little angle symbol), gives an
        expression in A and B that is wrong (the A and B are
        interchanged so A is the angle and B is the magnitude).

     o  If the clock is displayed during an ARCHIVE via RS-232, there is
        a chance (not 100%) that calculator memory will be cleared,
        after the transfer.  The work-around is to turn the clock
        display off before doing the transfer.  Should your memory be
        cleared, you will have to restore the contents of memory from
        the archive.


     o  TRNC and RND allow for an array in level 2 and a symbolic in
        level 1 of the stack. This allows you to put an array in a
        symbolic.  Example: [ 2 3 ] '7/8' RND returns

     Roms: A-E

     o  There's a bug in the EquationWriter that is "fixed" in the Rev J
        ROM.  See Appendix C-1 for details.

     Roms: E, J

     o  BESTFIT: Occurs when a two dimensional array is stored in \GSDAT
        (SigmaDAT).  Pressing the BESTFIT softkey multiple times will
        leave a lot of useless reals on the stack.

     Rom: K

     o  First HP48 G/GX released; includes various bugs affecting ports.
        Therefore, the version K ROM was only used in HP48 G units.

     Roms: K, L, M, P

     o  XROOT Function fails when used with list processing unless X=Y.
        It does not corrupt memory.

        FIX: Preceed any XROOT which will use list processing with a
        SWAP

     Rom: L

     o  Second HP48 G/GX released; fixed the port bugs.  This ROM
        version is that present in the 2,000 HP48 GXs sold at the ASEE
        conference for $90 apiece.

     Roms: L, M

     o  HP48 GX may lose all of user memory when: clock is displayed, a
        library object is be stored in user memory, and a RAM card is
        lugged in to port one and merged with User Memory.  If all four
        of these conditions are present and the calculator is turned on
        when the clock is being updated by the system, a loss of all
        User Memory may occur.

        FIX: Just type the following in on your calculator:


          << RCLF -> f << -40 CF OFF f STOF >> >> 91.3 ASN

          Then turn on USER mode


     o  EquationWriter/Character Picker Bug: If the size of the equation
        is greater than the regular size of the screen, calling the
        Character Picker in Equation Writer will garble the screen.

     o  If you store an object into a port > 1 while there is a card
        installed in slot 1, the end-of-obj-sequence marker (00000) is
        written to port 1 instead to the destination port.  This will
        cause the 'Invalid Card Data' warning to pop up each power on
        after a while and, in addition, the memory of port 1 gets
        currupted (if it's writeable).  A temporary fix is to remove the
        card from slot 1 when changing the contents of the card in slot
        2.  However a better fix is to get the STOFIX library (available
        on GD#10 or at HPCVBBS, ~1K in size).
     o  Tail Bug: The TAIL command returns an error on single length
        strings.  This was fixed to return an empty string in later
        Roms.  Examples:


          "X" TAIL --> Error: Invalid Dimension (Rom M)

          "X" TAIL --> "" (Rom R)


     Rom: M

     o  Evaluating a tagged object which contains an operator (+, -, *,
        /, etc) as the second or subsequent character will leave an
        External and System Binary on the stack, as well as the original
        object.

     Roms: L, M, P

     o  SigmaDAT: Put a NON-MATRIX in \GSDAT (SigmaDAT), run STAT
        graphical apps, edit \GSDAT.  Causes a crash.

     o  XRECV will fail or cause memory lost if the amount of free RAM
        left is not about twice the size of the expected file.

        FIX: See FXRECV on GD 9.  Note that FXRECV is not necessary for
        Rom R, and in fact will not even run properly on Rom R.

     o  RREF does not transform the matrix into Row Reduced Echelon Form
        correctly if the first column of the matrix consists entirely of
        zeros.  It may also return incorrect answers in some matrices.

        A work-around for this bug is to delete any leading all-zero
        column(s) from the matrix; this may be done using the Matrix
        Writer, via its -COL menu key, or via commands: 1 COL- DROP (to
        drop the first column).  Since row-reduction operations never
        change any all-zero column, you already know in advance that the
        given column(s) must be all-zero in the final result.

     Roms: L, M, P, R

     o  portnum: { dir ... var } RCL/EVAL fails if portnum >= 2

     o  Rotation rate to angular frequency conversion bug.  See Appendix
        C-2 for a complete write-up.

     Roms: M, P, R

     o  Repeated executions of FFT or IFFT can cause a memory loss.  The
        FFT and IFFT warmstart problem is caused by a CPU return stack
        overflow during interrupt handling.  The problem can only occur
        when the argument to FFT or IFFT is an MxN matrix with both M >
        1 and N > 1.  The vector argument case is immune to this
        problem.

        FIX: To compute the FFT of a matrix without risking warmstart,
        expand the matrix into its row vectors using ->ROW, compute the
        FFT of each row vector, collect the results into a matrix using
        ROW->, expand the matrix into its column vectors using ->COL,
        compute the FFT of each column vector, and finally collect the
        results into a matrix using COL->.  Except for less precision,
        this is the same result as would be obtained by applying FFT on
        the original matrix.  Use the same procedure with FFT replaced
        by IFFT to compute the IFFT of a matrix.
        Here are program examples implementing the "Matrix FFT" and
        "Matrix IFFT":


          MFFT     << ->ROW FFTLP ROW-> ->COL FFTLP COL-> >>
          MIFFT    << ->ROW IFFTLP ROW-> ->COL IFFTLP COL-> >>
          FFTLP    << -> n << 1 n START n ROLL FFT NEXT n >> >>
          IFFTLP   << -> n << 1 n START n ROLL IFFT NEXT n >> >>


     o  Equation Writer/Equation Library interaction bug: If you pick an
        equation from the EQ library, enter solver for that equation,
        enter an algebraic on the stack like 'X^2', and press the down
        arrow key to view algebraic in EquationWriter, the name of the
        equation will appear in the EquationWriter along with the
        unassociated algebraic.

     Roms: M, P

     o  BESTFIT: Occurs when a two dimensional array is stored in \GSDAT
        (SigmaDAT).  Pressing the BESTFIT softkey multiple times quickly
        can cause a warmstart, or SigmaDAT to be erased. This occurs
        sometimes just by pressing BESTFIT repeatedly, regardless of
        \GSDAT content.  This bug can also be triggered by pressing the
        BESTFIT softkey quickly after pressing any other key.  Simply
        pressing MODL then BESTKEY quickly will trigger the bug.

     Rom: P

     o  PROOT: If you put a matrix of coefficients on the stack and
        press PROOT repeatedly, you will get a warmstart.

     Roms: A-R

     o  MatrixWriter Bug: This shows up when deactivating and
        reactivating any of the two direction movement fields.  If you
        do this, the active matrix field won't move as it's supposed to.
        For example: Launch the matrix writer (check that your GOFORWARD
        field is activated).  Type [1] [ENTER]. The active matrix field
        moves forward as it should.  Deactivate the GOFORWARD field and
        activate it again.  Now enter [2] [ENTER] [3] [ENTER]. The
        digits should show up on the same row, but they don't, because
        after you deactivated and reactivated the GOFORWARD field, the
        active matrix field stops moving according to the movement
        fields.

     o  DTAG Bug: When the DTAG command is executed without any
        arguments on the stack, the error message "XLIB 0 0 Error" is
        given, which is non-standard.

     Roms: K-R

     o  Equation Library Solver and Multiple Equation Solver Bug:
        Pressing MSOLVR or MUSER after setting user flag 63 can cause
        Memory Clear.  Example: CLEAR, 63 CF, EQNLIB, down-arrow, ENTER,
        down-arrow, [SOLV], NXT, 63 SF, right-shift MUSER, DROP  -->
        Memory Clear.  This bug is also found in the HP Solve Equation
        Library Card (HP 82211B, but not 82211A) for the SX.


  3.6.  What is new with the revision "J" ROM? (S/SX)

  The revision J ROM has a faster equation writer, as well as some bug
  fixes.  Scrolling of graphics is also faster.
  One "problem" is that the revision J ROM changed some undocumented ROM
  entry points, which broke those programs that used them.  If you have
  a Rev J ROM, you will not be able to run some old programs.


  3.7.  What happened to ROM revisions G, H, I, O, and Q?

  These versions either were never released to the public, or were
  skipped over.

  I have received confirmation of the existence of a HP48 S with ROM
  revision F.  So it appears revision F was in fact released to the
  public, although very few must have made before revision J came out.


  3.8.  Can I upgrade my HP48 S/SX?

  When the G/GX first came out, HP had a trade in program.  This is no
  longer in operation.  The only option remaining is to try to sell your
  S/SX privately.


  3.9.  Can I upgrade my buggy GX to the latest ROM revision?

  As far as I know, not any more.  They had a program a in early '94,
  but it is over now.  Contact the following for more info:


       Hewlett-Packard Corporation
       Calculator Support
       1000 NE Circle Blvd
       Corvallis, OR 97330

       Phone: [phone]


  3.10.  What's the latest ROM version?


  o  Revision R is the latest ROM version of the G/GX series.

  o  Revision J is the last ROM version of the S/SX series.


  3.11.  Why would I buy a S/SX rather than a G/GX?

  Here's the top reasons to buy a S/SX instead of a G/GX (Thanks to all
  who contributed):


  1. May be slightly cheaper, having only 32K RAM.

  2. It isn't THAT outdated.

  3. So what if it's a little slower?

  4. You didn't need all those useless equations, graphics capabilities,
     and math and science functions anyways!

  5. If you break it, you're out of less money!

  6. You like seeing how much you can fit into 32K RAM.

  7. You like slow file transfers, using Kermit instead of X-Modem.

  8. You want to be able to use all those lists of SYSEVALs for the SX.

  9. You like having only 3 ports available max.  33 is ridiculous!

  10.
     Since it doesn't have a built in equations library it is less
     likely to be banned on tests.

  11.
     Only wimps need GUI's, dialog boxes, and choose lists.


  4.  Questions about the Operating System and Using the HP

  4.1.  How do I find the checksum of an object?

  Many documents (including this FAQ) make references to the "checksum"
  of an object.  This is a 16-bit user binary resulting from a CRC
  calculation on the contents of an object.  This binary is supposed to
  be relatively unique, with only 1 change in 65536 of accidental equal
  checksums on two different objects.  This allows you to distinguish
  programs that look the same but may be quite different (even if the
  size of them is the same).  It is also often used to verify correct
  transmission of files.

  You can find the checksum of an object using the BYTES command.  This
  will return you two things - the size of the object in bytes on level
  1, and the checksum on level two.  Note that while the checksum of a
  variable name is the same as running the checksum on the object
  itself, the sizes will be differ by 4.5 bytes + the size of the
  variable name itself.

  In rare cases the checksum of two objects can be the same, even if the
  objects are different.  This is due to the limited nature of the
  HP48's checksum function.  You can use the SAME command in these
  cases.


  4.2.  I typed RULES on my G/GX and got a crossword puzzle!

  From: Joe Horn

  Many commercial programs (like Windows) have similar hidden screens
  that list the program's design team.  Since they are always so cute
  and well hidden, they are often referred to as "Easter eggs".  The
  RULES command on the G/GX is one such example.

  Try using the RULES command.  The names you see are as follows:


       /----------------------\
       |            M G       |
       |      P   DIANA       |
       |    CHARLIE X B     D |
       | BILL U   N  TED    A |
       | O  A L   N    ALCUIN |
       | B  I    JIM   V      |
       |  RON     S    E      |
       \----------------------/


  ALCUIN was the HP-internal code name of the HP48 G during development,
  because Alcuin was Charlemagne's teacher, and Charlemagne, as you
  remember, was the code name of the HP48 SX.

  The other names in the "Easter egg" above belong to:


  o  BILL Wickes (list processing; "Father of RPL")

  o  CHARLIE Patton (RPL operating system)

  o  TED Beers (parameterized outer loop; interactive stack; key
     handling system; high-level display management; input forms)

  o  DIANA Byrne (project manager; plotting; graphics)

  o  GABE Eisenstein (EquationWriter)

  o  BOB Worsley (I/O)

  o  PAUL McClellan (unit management; math)

  o  CLAIN Anderson (product manager; marketing)

  o  DENNIS York (manager)

  o  JIM Donnelly (EQ LIB; list processing; variable tic logic;
     developer support)

  o  MAX Jones (menu system; editing)

  o  DAVE Arnett (hardware)

  o  DAN Coffin (manuals)

  o  RON Brooks (marketing)


  4.3.  Why does my HP48 occasionally "freeze" for a moment?

  The HP48 must occasionally do "garbage collection" to free up unused
  memory, and it is this garbage collection that is causing the
  momentary "freeze".  "Garbage collection" is where the HP48 scans
  through memory, looking for objects that are no longer used.

  Using less stack supposedly makes garbage collection go faster.

  The easiest way to force a garbage collection is to run MEM DROP.
  Otherwise you can use #05F42h SYSEVAL or the SysRPL command GARBAGE.


  4.4.  What do I do if my HP48 locks up?


  o  NOTE: If you have it, read the sections in the GX manual starting
     on page 5-16, "Special Memory Operations", and "Testing Calculator
     Operation" on page A-9.

  o  NOTE: under most circumstances, your calculator should never lock
     up.  Some earlier versions of the G/GX do this due to bugs.  Of
     course, depending on the program being run, it may appear to lock
     up, but pressing the "ON" key usually interrupts whatever the
     calculator is doing.  If it does lock up, this is usually caused by
     a buggy assembly-language or system RPL program, and, chances are,
     the memory contents of your HP48 are gone (as in "destroyed",
     "terminated", "wiped out", "deleted", etc.).
  1. First, check the batteries to make sure that they are installed
     correctly.

  2. Next, try is pressing the "ON" key again and again very RAPIDLY.
     The operative word here is "rapidly".  It's possible to write a
     program that can only be interrupted during a very narrow window,
     and so you must press the "OK" key again and again very rapidly to
     interrupt the program.  If the calculator doesn't respond within
     ten or so seconds, go on to the next step.

  3. Press "ON-+" a couple of times, just in case the LCD display
     intensity was turned down.  Here, "ON-+" means:

  o  Press and HOLD DOWN the "ON" key.

  o  Press and release the "+" key, WHILE HOLDING DOWN THE "ON" KEY.

  o  Release the "ON" key.

  4. If this doesn't work, the next thing to try is ON-C.  This is a
     "warm-start" or "system halt".   Note that this will CLEAR the
     stack.  Here, "ON-C" means:

  o  Press and HOLD DOWN the "ON" key.

  o  Press and release the "C" key, WHILE HOLDING DOWN THE "ON" KEY.

  o  Release the "ON" key.

  5. If this still does not work, it is possible that the HP is not
     responding because it is not accepting input from the keyboard.  It
     is possible to execute a system halt without the keyboard using the
     hidden reset button.  The reset button is hidden under one of the
     two upper rubber feet on the bottom of the calculator (it's under
     one of the two feet near the serial connector and I/R port).  Note
     that the location of the reset button (under which foot) varies
     from calculator to calculator.  If you gently pull out the rubber
     feet, you'll notice that there is a small hole under each foot.
     The reset button is located in the hole that has an "R" next to it.
     Once you've located the correct hole, you press the button by
     GENTLY sticking an unbent paper clip, into the hole with the "R"
     next to it.  Hold for one second and remove.

  6. The next thing to try is a complete memory reset.  Depending on the
     state of your calculator, this may or may not preserve the contents
     of memory.  At the very least, even if the contents are preserved,
     the contents of the HOME directory will probably be moved into a
     new directory below HOME (HOME will be empty with the exception of
     this new directory); you'll have to manually move the items back
     into HOME.  To perform a complete memory reset, press ON-A-F.  This
     means:

  o  Press and HOLD DOWN the "ON" key.

  o  Press and HOLD DOWN THE "A" key, WHILE HOLDING DOWN THE "ON" KEY.

  o  Press and HOLD DOWN THE "F" key, WHILE HOLDING DOWN THE "ON" AND
     "A" KEYS.

  o  Release all of the keys.

  o  At this point, the calculator will ask you if you want to recover
     memory.  Answer "yes" to this question.  Note that this can take a
     long time.  If you answer "no", all of memory will be cleared (the
     old contents will be lost).

  7. If that fails, you should still be able to induce a complete memory
     reset by removing your batteries and pressing ON several dozen
     times.  This will drain the capacitor that stores information when
     the batteries are removed, and you should get a "Try to Recover
     Memory?" prompt if you have pressed ON enough times to reset your
     calculator.  If this doesn't work you can try taking the batteries
     out for a few hours and then putting them back again.  You should
     definitely try this method before even considering the next step!

  8. WARNING: the next method is HIGHLY unrecommended!  Permanent damage
     to your HP can result if you try this.  In particular, you could
     fry a couple diodes used to protect your HP48.  You have been
     warned!

     If your HP48 does not respond to any of the above attempts, you
     might consider reversing the polarity of 2 of the 3 batteries VERY
     BRIEFLY, pressing ON, then correcting the batteries.  Your HP48
     should start with a "Try to Recover Memory?" prompt.  Even
     reversing only 2 of the 3 batteries is dangerous, but it is safer
     than reversing all 3 batteries.

     Note that simply shorting the battery terminals will not discharge
     the storage capacitors.  There are diodes between the battery
     terminal and the storage capacitors which prevent the DC current
     from flowing backward.

     This method apparently drains the capacitors and reverse charges
     them by running current through the parasitic input protection
     diodes in the various CMOS chips.

  9. If all of the above fail, or if you decide not to try the last
     step, you may have to contact Hewlett Packard for service.


  4.5.  My HP48 seems to take longer to turn on and off.

  The usual causes for this are RAM/ROM cards and libraries.  When you
  turn the calculator on, it checks RAM (the more you have, the longer
  it takes), and checks to see if any libraries need initializing.

  Also, having a lot of alarms can supposedly also cause this.


  4.6.  What are all the different ON-KEY combinations?

  From: Dave Arnett


     ON In most cases, this will move you to, or toward, the stack
        environment.


     ON+A+F
        This is the manual Coldstart.  It will break out of almost any
        hung program, and offer you the dreaded option... "Try to
        recover memory?"  Note that this is your next-to-last resort in
        a lock-up, so don't give your machine this three-fingered salute
        unless you really want to possibly clear memory.


     ON+B
        This is the Oops! key for ON codes.  For many ON sequences, this
        cancels the operation, so long as you press the B before
        releasing the ON key.  Try it sometime, if you must, just so you
        remember it.  It can be a life-saver, in case of an accidental
        ON+A+F in process, or even accidentally hitting ON during a
        plotting routine.


     ON+C
        This will initiate a Warmstart.  You'll lose the stack and PICT,
        but it will often get you out of a locked up program with memory
        intact.


     ON+D
        Enters interactive test mode.  Back up your own machine and play
        around.  Exit this test mode with Warmstart, ON+C.  See the next
        question for all the various tests available here.


     ON+E
        Starts a looping self-test mode.  Kinda dull after the first
        five minutes, but it keeps a rather solid tempo.  Exit with
        Warmstart, ON+C.


     ON+4
        Cancels repeating alarms.


     ON+1
        Screen dump utility.


     ON+'+' and ON+'-'
        Adjusts display contrast.


     ON+SPC
        Initiates Coma Mode and clears Warm Start Log.  In Coma mode,
        all the clocked activity is halted.  The battery power drain is
        basically the few nano-amps [nA] necessary to sustain your RAM
        contents.  The Warm Start Log is a nearly bullet-proof area of
        memory which keeps track of the last four hazardous events.
        View it using the command WSLOG.  This log is one of the few
        things not cleared by a Coldstart.  But it is cleared by ON+SPC.
        Enter Coma this way if you want to clear the Warm Start Log, if
        you are planning to study crystal healing in Tibet for a few
        years and want to keep your pirated version of Tetris alive, or
        you just have a low power fetish.  Exit Coma mode with the ON
        key (tough to remember, huh?), and plan to find your stack
        cleared out.

        Two additional notes on this Coma stuff.  First, I'm not gonna
        try to list the log codes in WSLOG.  Sorry!  Second, if your
        machine is on, and you drop the batteries out, you will usually
        end up in a coma mode to preserve power.  WSLOG will not be
        cleared.  Instead, you will find a code 1 entry there.  Some
        people are paranoid and want to be in Coma when they change
        batteries, just in case they have a sudden emergency call from
        the Prime Minister and don't get back to their battery change
        for a half hour.  If you are one of these...  shall I say,
        weenies?  No, that would be unprofessional ...users, then I
        recommend you use the ON+SPC entry route, rather than the
        kamikaze method of dropping batteries with the machine running.
        Myself, I just turn the machine OFF, like the manual says.

        Now, a Coma story... sort of.  During the G/GX development, I
        maintained a small number of units on which I changed ROM chips
        as incremental code releases came out.  This was so folks like
        Bill Wickes and Jim Donnelly could have fully-real hardware to
        test, instead of just the EPROM handsets some of you may have
        seen.  We always backed up anything of importance in the machine
        before we did this.  But I got into the habit of using ON+SPC
        before I opened up the calculator.  Better than half of the
        time, I could remove the batteries, open the case, desolder the
        old surface-mounted ROM chip, solder down a new chip, and
        reassemble the machine... with all of RAM intact!  When I
        pressed ON, I'd come right back up without a "Try to Recover
        Memory?" prompt.  Pretty good, huh?  The folks who put that mode
        into the machine certainly weren't in a coma.


  4.7.  What are the different interactive self-tests?

  Pressing ON-D enters the interactive self test function of the HP48.
  When you first press ON-D, your HP will beep and you will see 3
  vertical lines, one on each side of the screen and one in the middle.
  You can exit this mode with a Warmstart, ON-C.  The tests are:


     [A]
        Displays CPU speed

     [B]
        LCD test.  Press Enter to cycle through the tests

     [C]
        Internal ROM test

     [D]
        Internal RAM test

     [E]
        Keyboard test.  Starting with [A], press all the keys in order,
        left to right, top to bottom.  If all goes well, the HP will
        show "KBD1 OK".

     [F]
        Partial keyboard test

     [G]
        ESD test monitor.  Battery status is shown by bars.

     [H]
        UART loop-back test

     [I]
        Wired UART echo

     [J]
        Shows what cards are plugged in.  Press any key a few times.

     [K]
        Test RAM cards in ports

     [L]
        Blanks display

     [M]
        Sends system time from IR port

     [N]
        Receives system time from IR port (have another HP send it)


     [O]
        IR loop-back test

     [P]
        IR UART echo

     [S]
        Shows test start time

     [T]
        Shows test fail time

     [U V W X Y Z]
        Looping test

     [ENTER]
        Initialize test times

     [DEL]
        Test summary

     [BACKSPACE]
        Enters memory scanner (SX only)

  When the HP48 is in test mode (ON-D or ON-E), the test results that
  are displayed on the screen are also sent to the serial port at 9600
  baud, 8 bits, no parity, 1 stop bit.  This seems to be unaffected by
  any settings in IOPAR, PRTPAR, or the system flags.  I can only guess
  that this feature was included for factory testing purposes.  This
  does explain, however, why the I/O annunciator lights up so much
  during the self test.


  4.8.  Why do I get an ESD error when I check my batteries with the
  self test?

  From: Detlef Mueller

  If your HP48 batteries are low, try this test with fresh alkaline
  AAAs. This test first records the CRC of a RAM segment, then starts a
  loop where it creates power peaks and recalculates the CRC again until
  you press a key or the CRCs differ. In the latter case one or more
  cells of your RAM were "Electro-Statically Discharged" and the test
  exits with the last CRC done. If there's a hardwaer problem, this
  number should differ in consecutive executed ESD tests - with fresh
  AAA alkalines! Old ones or non alkaline batteries may cause trouble
  under this test condition.

  If the test runs continuously, the bars on the screen reflect the
  battery status (low bat if bar is there) of port 2 (below the 2), port
  1 (below the 1), and the main AAAs (below 0). If the AAAs are very
  low, the V bar comes up.


  4.9.  I can't account for some of the RAM in the HP48!

  The HP48 S/SX/G have 32K base memory, and the GX has 128K.  However
  not all this memory is available to the user.  The operating systems
  uses memory for system variables, flags, fonts, last stacks, last
  arguments, last menus, and such.  It also can be any one of a number
  of things:


  1. Enabling the use of LAST STACK, LAST ARG, LAST CMD, etc., uses up
     extra RAM, as the calculator has to keep track of the last stack,
     arguments, command, etc..  This is particularly important with LAST
     STACK if you have a large/complex stack, as the HP48 has to keep
     enough information around to recreate the stack after each
     operation.  You can clear out these variables by pressing ON-C (but
     also note that this will clear out the stack, the graphics PICT,
     etc.)

  2. From William Wickes, a member of the HP48 development team: Here's
     a candidate for "most obscure way to use up memory on the HP48 SX."
     When a program executes DOERR with a string argument, the string
     and hence the program too if the string is embedded in the program
     are referenced for the sake of the ERRM command.  Thus if you purge
     the program, the memory used by the program is not reclaimed until
     the ERRM reference is updated to a new string.  If the string is in
     a port, you will get the Object In Use error if you try to purge
     the library or backup object containing the string.  A system halt
     prior to a PURGE will not help unless the object is in port 1 or
     port 2 (it will reclaim memory held by a successfully purged but
     still referenced object).  For port 0 objects, the only way to
     break the reference is to execute DOERR again with a new string.

  3. Occasionally, I have had problems with libraries disappearing, but
     still taking up memory.  I found that an "ON-A-F" reset will cause
     these libraries to re-appear. If you still cannot account for a
     large chunk of memory, I would suggest a hardware reset, after
     backing up your memory.


  4.10.  What are the best methods for installing and removing
  libraries?

  To install a Library:

  1. Download it into a variable of the calc.

  2. Place the library on the stack.

  3. Type the number of the port in which you want to store the library
     in.  0 is appropriate if you do not have any expansion cards.

  4. Press STO to store the library in that port.

  5. Turn the calculator off and then on, or press ON-C, to finish
     installation of the library.

  Sometimes you have to purge the variable containing the library before
  storing it in a port, if you are low on memory.  See the next question
  for more information.

  If you have FXRECV installed: Just type a port number, hit FXRECV and
  the library will automatically go into the specified port.  All you
  have to do then in turn the calc off and then on to complete the
  installation.

  To delete a Library:

  Say you have library 1234 in port 0 that you want to delete.


  1. Go to the directory to which the library is attached.  In most
     cases this will be HOME.

  2. Enter :0: 1234

  3. Press [ENTER] or type DUP


  4. Type DETACH

  5. Type PURGE

  If this doesn't work, there may be a reference to the library still in
  temporary memory.  Try warmstarting with ON-C, then try again.

  Libraries with very low library numbers may require the addition of a
  constant in order to delete them.  For example, to delete a library 4
  in port 0 you can add 2048 to the library number, as follows:


  1. Type :0: 2052 DETACH

  2. Type :0: 4 PURGE

  Therefore, here is a fairly general program for detaching and purging
  most auto-attaching libraries; the only required argument being the
  real library number (e.g. 218 in the above case):


       \<< PATH SWAP HOME DUP 2048 + DETACH DTAG "&" \->TAG PURGE EVAL \>>


  4.11.  How can I attach large libraries?

  If have just successfully transferred a library to your HP, and try to
  store it in a port you may get an "Insufficient Memory" error.  This
  is because your HP is trying to make a duplicate copy to store in your
  port, but it doesn't have any memory to do so.  This is especially
  true on the HP48 S/SX/G since they only have 32K of memory built in.

  The solution is to push the library onto the stack, then purge the
  original variable containing the library.  At this point, the only
  copy of the library that exists is on the stack.  Now you can store
  the library in a port as usual.  This method avoids temporarily trying
  to have two identical copies in memory at the same time.

  For example, say you have a library in 'LIB' and you wish to store it
  in port 0.  You would enter the following:


  o  Go to the directory containing 'LIB'

  o  Recall the library to the stack: 'LIB' RCL

  o  Purge the original from user memory: 'LIB' PURGE

  o  Enter port number to store in: 0

  o  Press STO

  For the opposite problem - sending large libraries you can follow the
  reverse procedure.  That is, recall the object from the port to the
  stack, purge the original in the port, store it in a variable and then
  send it.

  Alternatively if the library is in a non-covered port (0/1/2 on SX or
  0/1 on GX) you can use the following simple program suggested by Dan
  Kirkland:


       \<< -> lib \<< 'lib' SEND \>> \>>


  This does not require a second copy of the library and avoids all the
  complications of trying to purge a library and then re-installing it.


  4.12.  What are those little numbers near the top of my screen?

  The little numbers are "user flags".  When you or a program sets any
  of the user flags 1 through 5, little numbers corresponding to the set
  flags are displayed at the top of the screen.

  The HP uses negative flags for setting various modes and functions,
  while positive flags were reserved for the use of the user.  To set a
  user flag type the number, then SF.  To clear a user flag type the
  number, then CF.

  Some programs will use the user flags without you being aware of it.
  So, if you have a "1" at the top of the screen you can type 1 CF to
  get rid of it.


  4.13.  Can I use my HP48 as a remote control?

  There are numerous programs available for using your HP48's IR port as
  a remote control.  However, the level of support depends on the
  particular unit you wish to control.  The HP48 is capable of
  reproducing many of the IR controls of many popular brands of
  appliances.

  However, some remotes run at speeds that the HP48 is unable to
  reproduce.  Due to their faster processor speed, the G/GX calculators
  are able to support more remote controls but are still limited in some
  cases.

  With typical remote programs you have to "teach" your HP48 by sending
  it the various IR sequences with the original remote control.  There
  are some advantages to using your HP48 however:


  o  You can impress your friends that you can use your calculator to
     control your TV!

  o  You can set alarms to turn your things on and off at predetermined
     times.

  o  You can use it as a universal remote.

  The best remote program by far is Remote by Bjorn Gahm.  It has a
  large database of existing remotes, meaning you may not have to
  "teach" your HP48 your specific remote if it is already supported.
  However it also have the ability to learn new codes.  See the best
  programs list (later in the FAQ) for the specific URL.


  4.14.  Can the HP48 be used as a DTMF phone dialer?

  To make phone dialing tones, you need to produce two simultaneous
  tones.  The tones used to dial phones are known as DTMF (dual tone
  multi frequency) tones, which consist of two tones at the same time.

  The speaker in the HP48 is not capable of supporting the DTMF tones
  because it can only make a single tone at a time.  The best the HP48
  can do is switch very quickly between one frequency and another.  Some
  attempts have been made in machine language to support DTMF, however
  they have been unsuccessful.  Therefore, you cannot use the HP48 as a
  phone dialer.


  4.15.  How can I run a program on warmstarts and/or power-up?

  You can use some of the utilities available on the Goodies Disks (see
  Appendix E.5 on where to obtain these):


  o  AUTOBOOT (GD #7) warmstarts every power-up

  o  AUTOEXEC (GD #10) Runs 'GO' every power-up

  o  AUTOPORT (GD #7) Runs &:AUTOEXEC every warmstart

  o  AUTOSTRT (GD #7) Runs AUTOEXEC every warmstart

  Some stack libraries come with support for AUTOEXEC or an equivalent
  built in (for example, the Java library supports AUTOEXEC).  If one of
  the libraries you have installed supports such a feature, you may not
  need any of the utilities above.


  4.16.  I could speed up my HP-28S.  How can I speed up my HP48?

  You can't, really.  Unlike the HP-28S, the clock speed in the HP48 SX
  is hardwired to 2 MHz, and to 4MHz in the HP48 GX.

  Digitalis  <http://www.Digitalis.de/> has a "speed-up" module
  available.  They sell 48G's with this module added (it looks like it
  adds about 50DM/$30 or so to the cost).  I'm not sure what it does,
  but I think it boosts the clock speed.  Apparently it can be turned on
  and off as needed, at the sacrifice of shorter battery life.

  However, in some cases, you can speed up the HP48 by turning off the
  display refresh, which supposedly takes up about 11% of the CPU time.
  Detlef Mueller submitted a program called SPEED to comp.sources.hp48
  that turns off the display refresh.  Of course, since it turns the
  display off, it is only suitable for long non-interactive runs like
  calculating large integrals, compiling, etc...  Look in the various
  HP48 archives for a copy.


  4.17.  What is the hidden directory and how do I access it?

  The "hidden directory" is a subdirectory of the HOME directory.  It is
  created on startup, and it contains variables with your alarms and
  user key configurations.    You can use the hidden directory to store
  whatever you want, however you CAN NOT ORDER the contents of this
  directory, as this causes memory loss.

  The name of the hidden directory is a null character, ''.  The only
  way to get a null character is to use a syseval.  You can use the
  following program to access the hidden directory:


           <<  HOME                            (changes to home dir)
               #15777h               (syseval to get null character)
               SYSEVAL                         (returns '' to stack)
               EVAL >>                       (changes to hidden dir)


  To exit the hidden directory, use HOME or UPDIR.  This will return you
  to the HOME directory.

  Also, by putting the null character as a part of your HOME custom
  directory, you can switch right into the directory by pressing the
  softkey.

  Note: The SysRPL command NULLID returns a null character to the stack;
  it is the same as doing #15777h SYSEVAL.


  4.18.  How can I recall one object from a memory archive?

  From: Joe Horn

  There is a little-known method of recalling objects from within
  archives.  Just make a list representing the PATH to the object, and
  tag the list with the port number.  Then hit RCL or EVAL.

  For example, if your archive in port 1 is called BKUP, and it contains
  a directory called GAMES which contains a program called REVERSI, you
  can run the game directly (without having a separate copy of REVERSI
  stored anywhere!) by:


       :1: { BKUP GAMES REVERSI } EVAL


  Or, you can RCL instead of EVAL, and it will be pushed onto the stack.


  o  This method only works in ports 0 and 1 in a GX.  It works on any
     port in the SX.

  o  This method works with directory objects stored as backup objects,
     as well as with the results of the ARCHIVE command, because they
     are both really the same thing.


  4.19.  Are there any key combinations that aren't in the manual?

  From: John Meyers

  Yes, on the G/GX there are a few keys that aren't mentionned.  They
  are:


  o  [right-shift] [down-arrow] = Review menu keys

  o  [right-shift] [right-arrow] = Kermit server mode

  [Right-shift] [View] is hidden in Appendix G (Operation Index) of the
  User's Guide [Edition 4] (which comes with the calc), among the
  several entries for the word VIEW.

  AUR [Edition 1] (in chapter 3, Command Reference, under SERVER) gives
  the alternate keys [right-shift] [cursor right] (but of course AUR
  doesn't come with the calc).  This alternative was left out of
  Appendix G of the User's Guide.  Donnelly's HP48 Handbook [2nd Ed.]
  even lists it first!


  4.20.  How do I find out about commands not in the GX manual?

  From: John Meyers

  Besides purchasing the Advanced User's Reference Manual (AUR), you can
  look in Appendix G of the G/GX User's Guide, which briefly summarizes
  every command available in the G/GX, including all the commands not
  mentioned anywhere else in the User's Guide.  Often even the brief
  description given in this Appendix is sufficient for you to use the
  command (and to know it exists!).

  Some notes on omissions, however:

  o  VERSION and "_" (attach unit) are missing in Edition 4.

  o  SUB works with arrays in the G/GX, but this is not in the HP
     manuals, nor in Donnelly's HP48 Handbook 2nd Ed 6/93.  You can
     specify any two "corners" of a rectangular sub-matrix (like with
     GET), and it extracts the sub-matrix.  Also works with vectors.


  4.21.  How can one delete (or purge) an entire directory?


  o  To purge a subdirectory and all that it contains, type in the name
     in single quotes, then PGDIR.

  o  To purge all variables in the current directory, but not the
     directory itself, type CLVAR.

  Note that with CLVAR, if the current directory contains a non-empty
  subdirectory, an error occurs at that point, and no subsequent
  variables are purged.


  4.22.  How does binary wordsize affect my calculations?

  From: John Meyers

  Some of the following (but not all) is in the User's Guide, under
  "Binary Arithmetic and Number Bases" (Chapter 15 of G/GX).

  The system flags contain a segment which specifies a "binary word
  size".  This word size limits how many low-order bits of a binary
  value are displayed on the stack, and equally determines how many low-
  order bits of the arguments and results of binary
  arithmetic/logical/shift operations are used.

  Curiously, the binary word size has no effect on entering values into
  the command line - what you originally enter is displayed in truncated
  form on the stack, but when you view it again in the command line
  (which temporarily reverts back to STD numeric display and 64-bit
  wordsize) you will find the complete value as entered is still intact.

  As soon as you begin using functions on that value, however, the
  arguments to binary functions get truncated to the current wordsize
  before the functions are executed, and then the final result of the
  function gets truncated again.

  You can recall the current wordsize using RCWS and set the wordsize
  using STWS.  STWS accepts a real number argument in the range 1-64
  (out of range values get adjusted to either 1 or 64), and it also
  accepts a binary argument, in which case the absolute value of the
  low-order 20 bits is used (just in case you wondered why #1048576d
  STWS RCWS gives an answer of 1).

  Don't try adjusting the binary wordsize in the hope of saving memory
  by using shorter values; every "user binary integer" (type 10)
  produced by User RPL occupies 13 bytes, no matter what the current
  wordsize; the HP48 just sets the leading bits to zero when displaying
  on the stack or performing calculations.


  4.23.  Can I add my own equations to HP's Equation Library?

  No, the Equation Library is in ROM, and can't be written to.  There
  are several programs which allow you to create your own equation
  library such as EQBrowser, EQ Lib, Equation Manager, and xMGR.LIB.
  All of these programs can be found at
  <http://www.hpcalc.org/utils/misc/>.


  5.  Questions about Math, Plotting, and Equations

  5.1.  Why does (1/3)*3 equal 0.999999999999?

  This is due to the way numbers are typically represented by computers
  and calculators.  There are infinitely many numbers, like `1/3' and
  `pi', that cannot be exactly represented internally (their decimal
  representations go on forever, and often cannot even be represented as
  a fraction, as in the example of `pi').  As a result, any calculations
  that use these numbers are bound to be off.


  5.2.  Why does my HP say that 0 to the power of 0 equals 1?

  Some claim that 0^0 is defined as 1, some claim it is indeterminate.
  The HP mathematicians decided to use the definition.  Here is some
  more concrete info shamelessly lifted from the Sci.Math-FAQ:


     Question:
        What is 0^0 ?

     Answer:
        According to some Calculus textbooks, 0^0 is an "indeterminate
        form". When evaluating a limit of the form 0^0, then you need to
        know that limits of that form are called "indeterminate forms",
        and that you need to use a special technique such as L'Hopital's
        rule to evaluate them. Otherwise, 0^0=1 seems to be the most
        useful choice for 0^0. This convention allows us to extend
        definitions in different areas of mathematics that otherwise
        would require treating 0 as a special case. Notice that 0^0 is a
        discontinuity of the function x^y.

        Rotando & Korn show that if f and g are real functions that
        vanish at the origin and are analytic at 0 (infinitely
        differentiable is not sufficient), then f(x)^g(x) approaches 1
        as x approaches 0 from the right.

        From Concrete Mathematics p.162 (R. Graham, D. Knuth, O.
        Patashnik):

        "Some textbooks leave the quantity 0^0 undefined, because the
        functions x^0 and 0^x have different limiting values when x
        decreases to 0.  But this is a mistake.  We must define:

        x^0 = 1 for all x,

        If the binomial theorem is to be valid when x=0, y=0, and/or
        x=-y.  The theorem is too important to be arbitrarily
        restricted! By contrast, the function 0^x is quite unimportant."
        Published by Addison-Wesley, 2nd printing Dec, 1988.

     References:
        H. E. Vaughan, The expression '0^0', Mathematics Teacher 63
        (1970), pp.111-112.

        Louis M. Rotando & Henry Korn, "The Indeterminate Form 0^0",
        Mathematics Magazine, Vol. 50, No. 1 (January 1977), pp. 41-42.

        L.J. Paige, A note on indeterminate forms, American Mathematical
        Monthly, 61 (1954), 189-190; reprinted in the Mathematical
        Association of America's 1969 volume, Selected Papers on
        Calculus, pp. 210-211.


  5.3.  What is RPN?

  Jan Lukasiewicz wrote a book on formal logic in 1951 that showed that
  mathematical expressions could be specified without parentheses by
  placing the operators before (Polish Notation) or after (Reverse
  Polish Notation) the operands.  For example, the expression:


       (4 + 5) * 6


  Could be expressed in RPN as:


       4 5 + 6 *
       6 4 5 + *


  Polish Notation is also known as prefix notation and Reverse Polish
  Notation (RPN) is also known as postfix notation.


  5.4.  Why did HP use RPN in their calculators?

  From: Dave Hicks <[e-mail]>

  In the years that followed Lukasiewicz's book, computer scientists
  realized that RPN or postfix notation was very efficient for computer
  math.  As a postfix expression is scanned from left to right, operands
  are simply placed into a last-in, first-out (LIFO) stack and operators
  may be immediately applied to the operands at the bottom of the stack.
  By contrast, expressions with parentheses and precedence (infix
  notation) require that operators be delayed until some later point.
  Thus, the compilers on on almost all modern computers converted
  statements to RPN for execution. (In fact, some computer manufacturers
  designed their computers around postfix notation.)

  At the time that the HP-35 was introduced, other pocket calculators
  typically used a partial algebraic model.  That meant they could
  evaluate trivial expressions like 4+5 but couldn't handle anything
  that involved parentheses or algebraic precedence.  The technology of
  the time didn't allow for full algebraic compilers in pocket
  calculators.


  RPN allowed HP to produce a pocket calculator that could evaluate
  arbitrary expressions using the available technology.  For many,
  learning a new style of entry was a small price to pay to be able to
  evaluate arbitrary expressions on a calculator.  Once the technology
  to produce algebraic compilers could fit into a pocket calculator,
  most RPN users had decided that RPN was more efficient and consistent
  for the user as well as for the calculator.  Also, because
  subexpressions are evaluated as they are entered, entry errors are
  more obvious with RPN.

  Another advantage to RPN is consistency between machines.  Early
  algebraic models had differing limits of the complexity of the
  expressions they could evaluate.  For example, TI catalogs from the
  late 70's listed how many levels of parentheses and pending operations
  each model could handle.  Even today if you begin to use an algebraic
  calculator, you need to determine just "how algebraic" it really is.
  For example, some switch to RPN for unary operators (ie 5 SIN rather
  than SIN(5)) and some can't directly enter an expression like:


        4+5
       -----
        6+7


  5.5.  Is there an alternative to calculating in RPN?

  Many people just can't get used to the interaction with the stack to
  do calculations.  A simple alternative is to place your equation in
  tic marks like '8+10*3' and to use the EVAL as an equals key.  This
  way you can enter numbers just as you would write them on paper.


  5.6.  Why do I get unexpected values when I add temperatures?

  Example: I add two temperatures like 34 deg.F and 11 deg.F, and I get
  504.67 deg.F.  Why don't I get 45 deg.F?

  This occurs with the S/SX only.  This behaviour changed in the G/GX.
  With the G/GX, adding 34 deg.F and 11 deg.F will give 45 deg.F using
  TINC and TDELTA.  However, the G/GX will only add or subtract
  temperatures if the units are the same; it is now an error if they are
  not.

  If the units attached to the number consists only of a temperature and
  nothing else, operations are done using an absolute temperature scale
  (relative to absolute zero).  If the units consists of a temperature
  and something else, such as degrees/minute, the operation will not be
  done using an absolute temperature scale.

  It also does not make any physical sense to add two temperatures.  You
  can't add a cup of water at 20 degrees C to a cup of water at 30
  degrees C and end up with two cups of water at 50 degrees C.


  5.7.  How can I add my own units?  What's the 1_? unit for?

  Note: Some later editions of the G/GX series manuals have some similar
  information on this subject.

  Another feature is the generic unit, 1_?.  It seems to be intended as
  a generic unit, to allow you to make new units not based upon any of
  the built-in ones.  You could use it to create a conversion utility
  for currencies or bits and bytes.  Before you create either, check the
  FTP sites to see what others have done in this regard.


  o  User units may be defined by creating a variable of any name (the
     new unit name), into which you store its definition in terms of
     other units, e.g. 2_mph 'stroll' STO; you can also use other user
     units in a definition, e.g. 3_stroll 'run' STO.

  o  You can then use the new unit name(s) in any custom or temporary
     menu, just the same as any other unit in the built-in Units
     Catalog.  For example, { 1_stroll 1_run ... } TMENU


       Here's an example. Convert this using ASC\-> and save it as 'sample'.

       "69A20FF78E000000005046F6E6574750ADA209C2A2C2A2070000F368B01B2130
       E20005046F6A756E650ADA20339201000000000000210C2A20F000046F6E6574
       768B01B2130640005086F6D6562750ADA20339200000000000000510C2A20F00
       0046F6E65747C2A20B0000D696E686B0168B01B2130B5000303435453047A204
       7A20C2A20F000046F6E65747ADA209C2A2C2A20F000046F6E6574768B01B2130
       B213047A20C2A20F000046F6A756E6ADA209C2A2C2A20F000046F6A756E668B0
       1B2130B213047A20C2A20F000086F6D65627ADA209C2A2C2A20F000086F6D656
       2768B01B2130B2130B2130F0DA"


  This is a sample directory with a custom menu.  Enter the directory
  and press the CST key.  Here you will see three units (truncated to
  fit the softkeys): donut, dozen, and homer. A dozen is defined as
  12_donut, and a homer is a rate of 1.5_donut/min (not part of the SI
  system).  These units may take SI prefixes described on page 10-5 of
  the User's Guide, so you may convert the value of 3_MW*h/kdonut into
  units of erg/mdozen using CONVERT, for example.  The items in the CST
  menu have the usual abilities of unit menu objects as described on
  pages 10-2 and 10-3 of the User's Guide.  These units can be used for
  math operations described on page 10-7 of the User's Guide, such as
  adding 2_donut to 1_dozen.

  Example: At your power plant, you have four control room operators who
  have a combined consumption rate of 2.28 homers.  How many donuts will
  they use in 5 minutes and 17 seconds?


  o  Enter the rate.

       2.28 [homer]


  o  Enter the time.


       Right-shift UNITS [TIME]
       5 [min]
       17 [s] +


  o  Multiply the time by the rate (*)

  o  Convert to dozens:

  CST Left-shift [dozen]


  o  The answer is a little over 1.5 dozen.


  5.8.  I want `pi' to be a numeric value, not a symbol.

  You are using "Numeric Constants Mode".  To turn this mode on or off:


     SX:
        Type -2 SF.  This turns the numeric constants mode on.  To turn
        it off, type -2 CF.

     GX:
        Go to the MODES menu (press green/right-shift MODES).  Hit the
        key for FLAG submenu.  Toggle the second flag "Constant -> symb"
        to turn on and off.


  5.9.  What tricks are there for manipulating matrices?


     SX:
        You can build up a matrix by rows using \GS+.  You can take a
        matrix apart by rows using \GS- These two commands (\GS is Sigma
        (Greek E)) add and subtract rows from the SigmaDAT Statistics
        matrix.  \GS+ takes a vector row and adds it to SigmaDAT, and
        \GS- takes the bottom row away from SigmaDAT.  \GS+ is
        accessible from the STAT menu with its own softkey.  \GS- can be
        obtained by pressing left-shift /GS+, or by typing it in at the
        command line.

     GX:
        The GX has many matrix functions built in.  See Appendix B-1.


  5.10.  Can I make my HP graph any faster?

  Try lowering the plotting resolution by typing #2 RES.  You can use
  larger values for faster speed at the expense of number of points
  plotted.  In the GX Plotting Options Menu this setting is known as the
  "STEP" rate.

  Alternatively, if you have a G series machine, you could try
  SpeedGraph, a fast assembly language plotter replacement.  See
  <http://www.hpcalc.org/> for a copy.


  5.11.  How do I plot inequalities?

  In the user's manual, inequalities are referred to as "truth plots".
  They are defined as expressions that return true (any nonzero real
  number) or false (0) results.  In a truth plot, a pixel is turned on
  if the expression is true, it's unchanged if the expression is false.

  For example to plot the simple inequality 'X>0' you could do:


       TRUTH
       -20 20 XRNG
       -10 10 XRNG
       ERASE DRAX DRAW

  For more complicated examples see your manual, or on a G/GX you can
  type TEACH to look at some of the built-in examples.  It may also be
  useful to plot the lines defining the outline true region.  This is
  easily done by changing the plotting style to FUNCTION or CONIC and
  plotting again, taking care not to erase any previous plot.

  Note that unless otherwise specified, every pixel in the display must
  be evaluated.  As such, truth plots can be very slow.  If you have a
  general idea on which values are going to return true, you can speed
  up plotting by specifying a smaller x and y plotting range.  You can
  do this by setting the "LO" and "HI" input forms on a G/GX, which can
  be different than the actual display range.

  If you are plotting the area between two equations, you speed up
  plotting dramatically by avoiding a TRUTH plot entirely.  Store the
  two equations as the first two items in the current EQ list.  Using
  NXEQ in the FCN menu will rotate the list as desired to plot both
  functions.  Then the area between them can filled in very quickly
  using the SHADE key of the FCN menu (in the PICTURE environment).

  Another hint for speeding up Truth plots is to set the resolution, say
  to 2 pixels or more, which also results in a different "shading
  pattern".  The resolution can be set with the RES command.


  5.12.  How do I take the logarithm of a base other than 10 or e?

  To take the log of a number other than base 10 or e, say log x base y,
  you use the formula:


         ln x
       --------    where ln is natural log (log works too)
         ln y


  A quick program to do it would be: << SWAP LN SWAP LN / >>

  With the input of:


       2: x
       1: y


  5.13.  How do I solve quadratic equations?

  The QUAD command is designed to solve expressions at degree up to two.
  One would expect the result of the simple expression 5=x/(1+x) to be
  x=-5/4.  But using the QUAD command, the HP gives the complex solution
  (0.5, 2.17944947177)  i.e. the principal value (with flag 1 set).
  What is the reason for this?

  The QUAD command is designed to solve quadratic equations.  If the
  equation is not of the form:


       a*x^2 + b*x + c = d*x^2 + d*x + e

  The HP48 calculates a quadratic taylor series expansion which is then
  solved like a normal quadratic equation.  The HP does the same when
  the equation is of a higher order.  In the example above, the equation
  x/(1+x)-5=0 has the expansion:


       -x^2  + x - 5 = 0,


  Which has two complex conjugate solutions.  However, if you multiply
  the equation by (1+x)/, you get:


       x = 5 * (1+x)


  Which can be solved directly with QUAD.  If the equation contains the
  variable only once, it's the best way to use the ISOL command instead.


  5.14.  Why do I get a complex answers for roots of negative numbers?

  This typically occurs for the (2n+1) roots of negative numbers, where
  n is a positive integer.  For example, to calculate the fifth root of
  -3125 you can enter:


       -3125^0.2


  The result is the complex number (4.04508497187, 2.93892626146) or in
  DEG mode (4.99999999999, >36).  The reason for this answer is that
  -3125^(1/5) has five different answers - arranged in a pentagon in the
  complex plane.  In general, y^(1/x) has x different answers (y^x with
  x irrational has an infinite set of answers forming a circle on the
  complex plane).

  Since 180/5 = 36 [degrees], this is the correct principal "5th root"
  of the negative argument in the complex plane; the HP48, unlike older
  calculators, does not turn "complex mode" on or off, so all "analytic"
  functions in the HP48 always accept complex arguments, and always
  return valid complex answers if suitable.

  To calculate the desired solution, you have to use the right-shifted
  V-key with input like this:


       2:        -3125
       1:            5


  Or you can use 'XROOT(5,-3125)' since XROOT is defined to both accept
  and return real values only.

  5.15.  Why doesn't '(-8)^(2/3)' give me the right answer (4)?

  From: John Meyers

  The reason is that the function ^ accepts and returns complex values
  whenever appropriate, and also always returns the "principal" answer
  in the complex plane, which may not be real if the argument is
  negative, even if there exist other real-valued possible results.

  Here are some UserRPL programs which handle this sort of general "real
  power of real" question, even with fractional powers, including the
  sticky issue of getting the right sign.

  Note that the "power" argument (level 1) may be either a fraction or a
  real number; we use \->Q in all cases to convert it to a fraction,
  which may be necessary to determine the correct sign of the answer.


       \<< \->NUM DUP SIGN SWAP ABS \->Q
         IF DUP TYPE THEN OBJ\-> DROP2 ELSE 1 END
         4 ROLLD * ^ SWAP XROOT \>>


  The version above is generally satisfactory for fractional powers
  which do not have a large numerator; otherwise an intermediate result
  might overflow, giving an invalid result.

  The next version is overflow-resistant, but there is sometimes a
  slight roundoff error from using ^ ABS:


       \<< \->NUM DUP2 ^ ABS SWAP ABS \->Q
         IF DUP TYPE THEN OBJ\-> DROP2 ELSE 1 END
         4 ROLL SIGN ROT ^ SWAP XROOT * \>>


  Neither of the above programs ensures that its arguments are actually
  real; other arguments (e.g. complex) can sneak by, possibly producing
  meaningless answers.  You can prevent this in either program by
  following \->NUM with OVER R\->B OVER R\->B DROP2

  For example, with -8 and '2/3' as arguments, (or even -8 and
  .666666666667 as arguments), the answer is 4.  To make the above into
  a user-defined function which can be used in algebraic expressions:


       \<< \-> p r \<< r p \->NUM \->Q IF ... END \>> \>> 'XPOWR' STO


  Then 'XPOWR(2/3,-8)' EVAL ==> 4  [using XPOWR() just like XROOT()]

  Note: There are actually two different XROOT functions in the HP48;
  the algebraic version of XROOT expects its arguments in the opposite
  order from the stack-based version of XROOT (which inadvertently gave
  rise to a list-processing bug in early G-series ROM versions: K, L, M
  and P).

  If you define XPOWR for yourself, as above, you will have to make sure
  that you use a consistent argument order for both algebraic and stack
  usage, unless you either make two separate functions or get into some
  fancy library-making, to duplicate something akin to the built-in
  "dual" XROOT functions.


  5.16.  How do I solve polynomials?

  Another fast way to solve quadratic equations (or polynominals of
  higher degree) is by using the PROOT command.  Place a vector with the
  coefficients of the polynominal on the stack.

  For example:


       x^3 - 9*x^2 + 26*x - 24


  Would look like:


       [1 -9 26 -24]


  Then press left shift, SOLVE (key 7), POLY (key C), PROOT (key A).
  The result is [2 3 4], which are the roots of the equation.


  5.17.  How can I do statistics for grouped data?

  Excerpt of postings from John Meyers

  You must replicate the individual values or you can use a weighted
  analysis.  For weighted analysis, Joe Horn's WEIGHT2 directory which
  can be found on Goodies Disk 8.

  For weighted mean of numeric grades (or grade equivalents), with the
  number of credits for each course being the weight, you can use the
  program below.

  First, fill in the statistics matrix, using any of the built-in
  statistics applications, entering each numeric grade equivalent in
  column 1, and the corresponding number of credits in column 2.  Then
  press the key for the program below, which returns three results:


  o  Weighted mean of column 1, using weights from column 2

  o  Standard deviation (estimated from samples entered)

  o  Standard deviation (of population actually entered)

  If you select an "X-Column" and/or a "Y-Column" different from the
  defaults (columns 1 and 2), then the results reflect the values in the
  "X-Column" using weights from the "Y-Column".

  The program below is a slight improvement upon WEIGHT3, in that it no
  longer requires SigmaPAR to exist (the standard default columns are
  assumed if not).  Credits go to Bob Wheeler for coming up with the
  algorithm, and to John Meyers for implementing the following program:

       %%HP: T(3); @ \-> is right-arrow, \v/ is Square Root, \GS is Sigma
       @ WMS - Weighted Mean and Standard Deviation, HP48G/GX
       @ Stack diagram: ( SigmaDAT and SigmaPAR ) -->  Mean, SDev(S), SDev(P)
       @ If SigmaPAR does not exist, then
       @ Col 1 (XCOL) is value and Col 2 (YCOL) is weight, by default
       \<< '\GSPAR' DUP VTYPE 0 < { DROP 1 2 } { RCL 1 2 SUB EVAL } IFTE
             0 0 DUP2 \-> x f w d m v
         \<< RCL\GS x COL- SWAP DROP ARRY\-> EVAL \->LIST
             RCL\GS f COL- SWAP DROP ARRY\-> EVAL \->LIST
             2 \<< DUP2 'w' STO+ m - * DUP 'd' STO
             w / 'm' STO+ m - d * 'v' STO+ \>> DOLIST
             m v w DUP2 1 - / \v/ ROT ROT / \v/
         \>> \>>^


  If all you want is the weighted mean, and not the standard deviations,
  then you can dispense with all of the above, and just use a shortcut
  posted in GD7/MATH/WEIGHT.DOC by Joe Horn (basically, it is
  Sum(X*Y)/Sum(Y), where Y is the weight for X).

  If you would rather replicate data points, then read on - however, if
  the "weights" associated with your data points are either very large
  or non-integers, then the following will be either very cumbersome or
  not possible, respectively.  Press left-shift STAT DATA (on G/GX) to
  get to the menu containing the "Sigma+" "Sigma-" and "ClearSigma"
  commands.

  Press "ClearSigma" to remove the old SigmaDAT.  The first data must be
  entered as a vector: For example [2 4] and pressing "Sigma+".  Now all
  other data pairs are entered without the brackets just as a pair
  separated by a space: e.g. 4 3 and pressing "Sigma+" and so on.

  "Sigma-" in the HP48 does not accept data; rather, it simply removes
  the last-entered data point/row, popping it back onto the stack for
  you (the result is always one vector or scalar).  If every point is
  removed, the statistics matrix is also deleted.

  Now we can understand Joe Horn's program which accepts a data
  point/row, in whatever form the HP48 is prepared to accept it (single
  number, vector, or group of numbers), plus a frequency (integer only)
  on stack level 1, and then appends the data point/row the given number
  of times.  Note that you must always supply a frequency, even if it is
  1, and that any meaningless "frequency" less than 1 will be treated as
  1.


       \<< -55 CF 1 SWAP START \GS+ LASTARG NEXT DROP \>>


  Obviously, \GS+ and \GS- represent the "Sigma+" and "Sigma-" commands.

  Example: If the Statistics Matrix (SigmaDAT) already has two columns,
  and if we want to enter the new data pair [ 3 4 ] five times, we can
  simply type 3 4 5 and then press the key for the above program (don't
  forget to use a data vector for the very first data row).

  For large frequencies, as noted, you will find this to be slow, not to
  mention the memory required for the multiple matrix rows; however,
  once you have literally entered every single data row, you can then do
  all the regression analysis and plotting you want, without the need
  for additional programming.
  5.18.  How do I generate a function table?

  An easy and versatile way is to use the powerful list processing
  capabilities of the HP48.  Generate a list with the x values, then
  perform the operations on that list.  For example:

  { .1 2 2.5 5 123.4 } SQ will output { .01 4 6.25 25 15227.56 }

  There are also several programs/libs to create a function table.  Take
  a look at  <http://www.hpcalc.org/> and search for "MathTools" by Jack
  Levy or "Table" by Diego Berge.

  If you are low on memory or want a customizeable program you can use a
  tiny User-RPL program. Here are two suggestions with different forms
  of the output.  All programs use the SEQ command, which is the key
  command here! (for further information read the manual).  Input is for
  example:


       5:    'SQ(x)'
       4:         x
       3:        11    (start)
       2:        25    (end)
       1:         1    (step)


  The first mini program will output a matrix with the calculated values


       %%HP: T(3)A(R)F(.);
       \<< SEQ OBJ\-> COL\-> 1
       COL\->
       \>>


  The second one will give x and f(x) in an array


       %%HP: T(3)A(R)F(.);
       \<< 4 DUPN 4 PICK 4
       ROLLD SEQ OBJ\-> COL\->
       6 ROLLD SEQ OBJ\->
       COL\-> 2 COL\->
       \>>



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