HPedia: The HP Calculator Encyclopedia By Eric Rechlin and Carlos Marangon

Also available in French, thanks to Khalil Haddad, Portuguese, thanks to Carlos Marangon, and Spanish, thanks to Roberto Pérez-Franco.

AC

Alternating current, the power coming out of an electrical outlet. In this US and Canada, this current alternates 60 times per second; in most other countries, the frequency is 50 or 70Hz. Some people have made a port for an AC adapter, to allow the HP48 to run on AC power, but not much information is known about how well this works.

ACO

Australian Calculator Operation, the design team recently started by Hewlett Packard to design a new calculator. Members of the team include Jean-Yves Avenard, Cyrille de Brebisson, and Gerald Squelart. All information is kept confidential, and a release date will not be given ahead of time, but perhaps this means our prayers will be answered!!!

AG

Alonzo Gariepy, an early HP48 user and creator of one of the first assemblers, using his own mnemonics, called AG mnemonics. Many people find AG mnemonics confusing when compared with HP mnemonics.

alkaline

Most commonly used type of single-use batteries. Last a long time, but are usually not rechargeable like NiCads and other kinds.

AUR

Advanced User's Reference

Hewlett Packard's advanced User RPL programming book, abbreviated AUR. This lists specific information about every built-in HP48 command, as well as numerous User RPL programming examples and tutorials. Jarno Peschier's review of this book is also available.

Alcuin

Code name for the HP48GX while in development.

aplet

Name of the programs that run on an HP38G.

argument checking

User RPL checks for the correct number and type of arguments before executing a command to prevent memory corruption. This is called argument checking. System RPL doesn't, so the programmer must add argument checking where needed.

Dave Arnett

Arnett, Dave

Member of the HP48 design team. He designed the hardware of the G series and now works in HP's printer-cartridge division.

ASC

A commonly-used method of converting binary HP48 files to ASCII text and vice versa. Converters are available for most platforms.

ASCII

American Standard Code for Information Interchange. This is the standard set of 256 characters used by most computers. The HP48 uses most of this set; however, some of the higher-numbered characters are special math characters. This means that ASCII Translation must be used to support the special characters. ASCII is pronounced "aski" rather than "ask-two" or "asc-dos" as some people mistakenly say.

assembler

A program which takes assembly source code and assembles it into machine code. Assemblers built into the HP48 sometimes accept RPL code also, translating it into assembly before assembling it. This includes Jazz's ASS command and MetaKernel's ASM command. On-PC assemblers, like HP Tools, usually have separate assemblers and RPL compilers (RPLCOMP and SASM).

assembly language

A very low level language for programming a computer. The HP48 has a Saturn processor, so it uses Saturn assembly. There are several different kinds of mnemonics and syntaxes used, however.

Jean-Yves Avenard

Avenard, Jean-Yves

A French man and the primary creator of the MetaKernel. He is one of the best, if not the best, HP48 assembly language programmers in the world. He has since been hired by Hewlett Packard and works for their Australian Calculator Operation.

bank switching

This is where, in an HP48GX, ports greater than 1 are swapped with port 2 since the Saturn CPU can only address the bottom 512k of memory. This is performed automatically by the RPL operating system, but assembly language programmers will have to be aware of bank switching. For the SX, some cards greater than 128k were made using manual bank switching. These cards had a switch on them for the user to select which bank (of 128k each) they wanted to access.

baud

In analog data transmissions, this is the number of symbol changes per second. Many people incorrectly say this when they mean bps. Note that even the HP48 says baud rather than bps, so there must have been a really stupid person on the HP48 design team. Most 28,800 bps modems operate at 3,200 baud. The term baud was named after the French engineer Jean-Maurice-Emile Baudot.

bint

Binary integer, used in System RPL and appearing on the stack as, for example, <1d>.

bps

Abbreviation for bits per second. This refers to the data transmission speed of a device. The HP48 operates at 9,600 bps with a symbol change rate of 2,400 baud

Bredahl, Sune

Creator of SolveSys, a very commonly used solver of systems of equations.

BZ

The best compression program for the HP48, by Mika Heiskanen. This program is 1.1k, or 300 bytes for the decompressor only, and is possibly the fastest and most efficient one on the 48.

Capacitor

capacitor

Electrical thing that holds power so when power is lost the powered device keeps running. The HP48 has a capacitor to keep the memory while the batteries are changed.

Carlier, Sebastien

Creator of Emu48, which is undisputedly the best HP48 emulator. It was originally written for Windows 95 and NT, but since the release of the source code, it has been ported to Windows CE.

Jim Carter

Carter, Jim

Founder of EduCALC, a dealer of HP calculators for 21 years. EduCALC, which was a primary reseller for calculators and calculator accessories, went out of business on December 31, 1997 because of business problems inside of HP and embezzlement by Jim's office manager.

CAS

Computer Algebra System, the name for the high-end symbolic math programs for computers, the HP48, and some TI calculators.

Charlemagne

Code name for the HP48SX while in development.

checksum

An value generated for a file which allows errors to easily be detected.

Chip

A simple game language. Interpreters for Chip games are available for many platforms, including the HP48.

comp.sys.hp48

The HP48 Internet Usenet newsgroup. Started in 1991, this group averages well over a thousand posts each month. All posts are archived by DejaNews, which is also useful for people who don't have access to a news server.

covered port

Any port greater than 1 on an HP48GX. Since the Saturn processor can only address 512k of memory, any port above 1 is bank-switched with port 2 in order to be accessed. The HP48SX only allowed ports up to 2 so bank switching wasn't needed.

CR2016

CR2016

This is the 3-volt lithium button cell battery used by the HP48's RAM cards to keep the memory powered when the calculator is switched off. Hewlett Packard says to replace the battery every year, but I know of some people who have gone for five years or more without replacing the battery.

CRC

Cyclic Redundancy Check, see checksum.

DC

Direct Current, the steady current provided by batteries in the HP48.

Cyrille de Brebisson

de Brebisson, Cyrille

French man; creator of most of the programming development tools in the MetaKernel. He now works for the HP ACO.

Darcy, Benoit

Creator of HP48ezine, the first and the best electronic magazine about HP48 calculators in French, available at http://home.nordnet.fr/~bdarcy/.

disassembler

Takes a program and disassembles the machine code into assembly language so it can be edited. HP48 disassemblers will disassemble System RPL and User RPL programs into their System RPL source code rather than assembly language.

Donnelly, James (Jim)

One of the creators of the HP48G series. He created the equation library, including the periodic table of elements, among other things. Jim also is the author of many HP48 books such as An Introduction to HP 48 System RPL and Saturn Assembly language and the HP 48 Handbook.

DTMF

Dual Tone Mean Frequency, the type of tones used in Touch Tone telephone systems. The HP48 piezo beeper can not produce DTMF tones, despite numerous efforts.

Easter Egg

Easter Egg

In regards to computer software, this is a hidden command, usually producing credits for the program. In the HP48G series, one can type RULES to show a crossword displaying the first names of the calculator's creators, as well as the code name of the HP48. Java also has an Easter Egg, accessible by typing SOL (for System Outer Loop; this was the original name of Java).

EduCALC

For 21 years, this was the best place to buy HP calculators and accessories. For many reasons beyond their control, they were forced to withdraw from business at the end of 1997. Since then, their name and web site have been purchased by Calculating Edge, although it's unfortunately not the same company it once was. Also there was a teacher's calculator, consisting of an HP calculator and a large external screen made in the late 1970s called the EduCALC, which is the company's first product and where it got its name.

Emu48

The free HP48 emulator for Windows 9x, NT, and CE.

emulator

A program which, using a ROM, simulates (or more correctly, emulates) a computer on another computer. Emu48 almost completely emulates an HP48 under Windows, allowing one to use the calculator on the computer screen.

Erable

French for "maple." This is an excellent algebra/calculus program for the HP48, with hundreds of functions. Unfortunately, it's around 100k.

Fiechter, Claude-Nicolas

An American, co-creator of ALG48, a leading algebra library for the HP48.

flags

There are 64 system flags (numbered -64 to -1) and 64 user flags (numbered 1 to 64) that can be used to control how programs and the HP48 operate. Flags can be manipulated with the CF (clear flag) and SF (set flag) commands, among others.

fraction mark

Abbreviated FM, this is the character that separates the integer from the fraction. This can either be a period (.) or a comma (,). The HP48 default (usually used in the US and Canada) is (.), like 602.12, and it can be set to (,) for other regions, such as Europe and Latin America, like 602,12.

GD

Goodies Disks, containing HP48 software compiled by Joe Horn, of which eleven were made from 1990 through 1997 and sold for $5 each through EduCALC.

grob

Short for Graphic Object, which is the file format used for HP48 graphics files. It encodes monochrome graphics in groups of four pixels, plus a header defining the image size.

Heiskanen, Mika

A Finn, the other co-creator of ALG48. Mika is also "the Father of Jazz," and wrote BZ and a number of other complex programs.

William Hewlett

Hewlett, William

One of the two founders of Hewlett-Packard. He founded HP with David Packard in 1939. Sometimes Hewlett and Packard are referred to as "Bill and Dave." Bill is still alive, although he no longer runs HP.

Hicks, Dave

Curator of the Museum of HP Calculators (MoHPC). He's a true calculator collector, owning nearly every calculator HP has ever made.

hidden directory

This is the null-named directory under HOME. User keys and alarms are stored here, and, if you're careful, you can store your own variables here. Note that the hidden directory is always cleared when you do an On-A-F, even if you choose YES to recovering the memory.

Joe Horn

Horn, Joseph K

More commonly known as Joe Horn, or simply -jkh-. Joe created the Goodies Disks from 1990-1997, and has been around in the HP calculator community for many years before that. Unlike too many other long-time HP calculator owners, who've since gone on to do other things, Joe still frequently posts to comp.sys.hp48.

HP82240B

Part number for the portable infrared printer for the HP48 and several older HP calcs. This printer uses rolls of thermal paper and can either run on batteries or AC power.

HP82240B

HPCC

Handheld and Portable Computer Club, of London, England, supporting the HP48/38/28 and older calculators and HP palmtops, such as the 71/75 and 95/100/200/300/600LX series.

HP Club do Brasil

Brazilian club of HP48 users founded on March 13, 1998 and maintained by Tacio Philip Sansonovski. This club has a home page at http://hello.to/hpclub.

HPCVBBS

Hewlett Packard Corvallis Bulletin Board System, a dial-up system allowing users to discuss HP calculators and download HP48 software. This was later available by telnet over the Internet, and has since shut down in favor of a web site only (and the BBS is now only Lynx pointed to the HP calculator website).

Hz

Hertz, or cycles per second. The HP48's CPU operates at around 2 million Hz in the S series and 4 million Hz in the G series. See MHz for more information.

ICQ

I Seek You, the Internet communication network, created by Mirabilis. Many HP48 users use this to communicate with each other, either via chat or instant messages (pages). Currently there are more than 6 million active members of ICQ, with a couple hundred on the HP Calculator ICQ list.

infrared

Abbreviated IR. High frequency electromagnetic waves, just below the visible red light. This is used for wireless communication in the HP48, for calculator to calculator transfers, calculator to computer transfers, and calculator to printer transfers.

IrDA

Infrared Data Adapter. This infrared data transfer specification is not supported by the HP48, although many portable computers have a 115kbps (or faster) IrDA port.

JASM

Laurent Jouanneau's on-HP assembler, using his own syntax and providing the basis for Julien Meyer's ADS. There have been many disputes as to whether Jazz or ADS is better, and the MetaKernel usually wins. ;)

Java

Simply the best free five-level stack replacement. This program, by André Schoorl, Will Laughlin, and Richard Steventon, speeds up many HP48 functions, displays algebraics in "pretty print" and adds a number of new functions. The HP48's Java program predates, and is unrelated to, the Java computer programming language.

Jazz

The most comprehensive programming development environment that runs on the HP48, written by Mika Heiskanen. Jazz supports User RPL, System RPL, and assembly language, with full debugging, a high-speed full-screen replacement editor, an RPL mnemonic table, a library creator, and much more. This uses the HP syntax for assembly language.

Kermit

Data transfer protocol supported by all HP48s and most communication programs. The HP48 implementation of Kermit is very slow, unable to transfer at more than about 2400bps, although the computer implementation is much faster. Kermit is the only HP48 transfer protocol that supports an ASCII transfer mode rather than just binary. Columbia University has trusts and copyright of Kermit. The name Kermit is after Kermit the Frog, of Muppets.

Laughlin, Will

Co-author of Java, mainly in charge of the ML decomp routines. From the US.

LCD

Liquid Crystal Display, the kind of display used on all HP48s and nearly all other calculators since the early 1980s. The HP48 LCD has 131 by 64 resolution, built-in monochrome, and simulated grayscale, and flickers at 64hz. The HP48 LCD is manufactured by Epson.

Levy, Jack

Creator of many excellent System RPL / assembly language programs, including Organizer, Scribe, MathTools, and more.

LIBEVAL

Evaluates a G-series object at the given memory address (as a user binary integer). Be careful with this command, as random memory addresses will almost certainly corrupt memory and crash the calculator.

library

Type of HP48 program object which can be stored in ports. A warmstart is needed for libraries to be functional. Libraries cannot be split (for editing) with the built-in HP48 functions; however, several library splitters and creators which run directly on the HP48 exist.

lithium

Type of battery technology used by the HP48's RAM card backup batteries.

Jan Lukasiewicz

Lukasiewicz, Jan

Polish, creator of the first "non-classical logical calculus" which many call Polish Notation. The HP48 uses the opposite of Polish Notation, called Reverse Polish Notation. (See RPN)

machine language

Abbreviated ML and also called machine code, this is the low-level binary code executed by the processor. Sometimes (incorrectly?) used to mean assembly language.

Marangon, Carlos

A Brazilian HP48 user; runs HP48 for Beginners (hpfb) and the Brazilian HP48 Ring, and he also translated the HP48 FAQ to Portuguese.

Carlos Marangon

Mastracci, Matt

Author of HP-IDE, an HP48 development environment for Windows, and several other programs.

Meta Kernel

Abbreviated MK, this is a 128k ROM card completely full of programs to speed up the HP48. It is entirely written in assembly language, with a replacement stack, editor, equation writer, matrix writer, file manager, and programming development tools.

Meyer, Julien

The best HP48 games programmer. Julien has written many G-series games in 100% JASM assembly language, including the 62k WarioHP Land, MarioHP Land, Dr. Mario, TennisHP, Meganoid Gold, and much more.

Meyers, John H

By far the most frequent poster to comp.sys.hp48. John seems to have a very intelligent response to nearly every question, and regularly contributes User RPL programs. He occasionally contributes System RPL, too.

MHz

Stands for megahertz, meaning million hertz, and in the case of the HP48 it measures the CPU speed. In G series calcs, the speed varies with temperature. Most HP48 G-series calcs are either around 3.73 or 3.93MHz; however, depending on the temperature, I have seen mine anywhere from 3.7MHz to 4.0MHz, although it usually hovers around 3.93MHz.

minifont

Name for the built-in 6-pixel-high font and also the UFL FNT1 6-pixel-high font. The built-in font is variable-width caps-only, and the FNT1 is fixed-width (4 pixels), with both caps and lower-case, fitting 330 characters on the screen at once.

Detlef Mueller

mnemonics

In the HP48, words used in place of memory addresses in User RPL, System RPL, and also assembly language. For example, DispEditLine is the mnemonic for #3A00Dh in System RPL. In order for mnemonics, an RPL table must be present. The HP48 has User RPL tables built in, but for System RPL one must install a table (typically 34k to 41k).

Moy, Arnold

Canadian, creator of ChemLab, Bank, Matrix, and many more fast assembly-language programs.

Mueller, Detlef

German, creator of a number of programs, including Sokoban. He worked with Raymond Hellstern on a few programs, forming a group called "Magic48ges". The original German spelling of his name, for systems supporting extended ASCII, is "Müller".

Richard Nelson

Nelson, Richard

Formerly the Technical Support Head of EduCALC for a decade and probably one of the most influential people in the HP calculator community. With Joe Horn, Mr. Nelson has taught an HP48 programming class.

NiCad

Nickel Cadmium, a kind of rechargeable battery technology. NiCad batteries were used in many older HP calculators, and some people use NiCad AAA batteries in their HP48s.

NiMH

Nickel Metal Hydride, a more advanced kind of rechargeable battery technology. These batteries, not yet widely available in the US for fear that they will hurt the disposable alkaline market, last almost as long as alkalines on each charge and are rechargeable up to 1000 times. AA NiMH batteries are in the US for use in digital cameras, but for AAA's (for use in the HP48) one must order them from Japan or some other country that has them. NiMH batteries used to be common in portable computers but lithium ion batteries, which are lighter, more powerful, and much more expensive, have mostly replaced them.

PAHHC

Philadelphia Area HP Handheld Club, an HP calculator and palmtop club serving the area around Philadelphia, PA, USA. This club, in its 20th year, is run by Jake Schwartz.

David Packard

Packard, David

The other co-founder (with William Hewlett) of the Hewlett-Packard Company. The name Hewlett-Packard was chosen over Packard-Hewlett with the flip of a coin in 1939. David died in 1996 at the age of 85.

Parisse, Bernard

French mathematics professor and creator of the Erable math library.

PC Card

Name of the type of card slots found in many portable computers. The HP48 uses PC Card Type I-sized slots, which are the thinnest. The slots are not PC Card compatible because of the different connector, so only specialized cards may be used in them.

PCL

Printer Control Language, the printer language used by all HP printers and many other printers and supported by the HP48 with an add-on program, written by HP.

PCMCIA

What an acronym! This was the former name for PC Cards, standing for Personal Computer Memory Card International Association, the industry group organized to develop it in 1989.

PDF

Portable Document Format, used by Adobe Acrobat for publishing multi-platform documents. Some HP48 programs have their documentation in PDF.

PDL

Roberto Perez-Franco

Programming Development Link, a DOS programming environment for creating HP48 User RPL programs, created by HP but no longer sold.

Perez-Franco, Roberto

A Panamanian HP48 user; he started the HPCalc+ICQ users list and has written several programs, including circuit simulators, in 100% UserRPL. His nick is HPlus!

Peschier, Jarno

From the Netherlands; creator of the HP82240B emulator and a lot more.

Piezo Beeper

piezo beeper

The HP48 has a piezo beeper as a speaker. This cannot create DTMF tones, for dialing a telephone, nor can it create stereo sound (this isn't a Gameboy! ;).

Pigallio, Lilain

French; creator of Ice Cube, and several other games.

pixel

Abbreviation for picture element; this is what each dot that makes up the screen is called.

POL

Parameterized Outer Loop, a commonly used function in System RPL programs.

port

Like a drive on PC's, this is a separate storage unit on the 48. A base HP48 has one port (0) but with expansion cards it can have 0-2 (on an SX) or 0-33 (on a GX, with port 33 inaccessible).

PostScript

Another printer language, this is also used for documentation files. It's abbreviated PS, and can be viewed with GhostScript.

PPC

Personal Programmable Calculator or Personal Programming Center

PPC Journal

HP calculator magazine, formerly 65 Notes and later PPC Calculator Journal (when the palmtop computers went into the PPC Computer Journal). It was published from 1974 to 1987. Scans of every PPC Journal is available on CD-R from Jake Schwartz.

PTR

Pointer, a way of addressing unnamed system objects in System RPL. All System RPL must be programmed with ROMPTR or PTR if a table isn't installed.

RAM

Random Access Memory; requires power at all times to remain intact. Since all of the HP48's memory is RAM, as soon as the batteries are removed one only has a few minutes before the capacitors are drained and the memory is lost.

Rechlin, Eric

North Dakota (USA) high school student, creator of the HP Calculator Archive, one of the most visited sites related to the HP48.

Renewals

Type of rechargeable battery made by Rayovac and commonly used in HP48s.

ROM

Read-only memory; this is the non-erasable internal memory in the HP48 which stores all the built-in programs. The HP48G series has 512k of ROM and the HP48S series has 256k of ROM.

ROMPTR

ROM Pointer, a way of addressing unnamed HP48G-series system objects in System RPL. All System RPL must be programmed with ROMPTR or PTR if a table isn't installed.

RPL

Officially stands for Reverse Polish Lisp. HP was originally not going to make this term public, and it was always referred to as simply RPL. HP later tried to make it stand for ROM Procedural Language, but Reverse Polish Lisp stuck. Some people call it Reverse Polish Language or Reverse Polish Logic, but neither is the official name.

RPN

Abbreviation for Reverse Polish Notation. This postfix notation is the input syntax that nearly all HP calculators use. There are basically two kinds of RPN. One, used in older calculators, has ENTER duplicate level one of the stack into the edit line, and the other, used in the 28/38G/48, has ENTER duplicate level one if the edit line isn't being used, and put the edit line on level one if the edit line is being used. RPN uses postfix notation, so 1+1 is entered 1 ENTER 1 + rather than 1 + 1 =. This may seem more confusing at first, but with more complex inputs it is much easier. Reverse Polish Notation was based on the works of the Polish Jan Lukasiewicz, who created the prefix notation ( + 1 1 ) called Polish Notation.

RS-232

Standard serial communications protocol used by the HP48, as well as most computers.

Saturn Chip

Saturn

Name of the processor architecture used in all HP calculators since the HP-71B. This 4-bit CPU was specially designed by Hewlett Packard for low power consumption and excellent math performance. The current implementation, in the HP48 G-series, operates at slightly under 4MHz and is made by NEC of Japan.

Schoorl, André

Maintainer of the HP48 FAQ, co-author of Java and HPSauce, and author of UFL. He's Canadian, and also has created numerous compilations of software, as well as a custom "lite" version of Jazz.

Schwartz, Jake

Leader of the Philadelphia (PA, USA) Area HP Handheld Club. He's run the club for 20 years, and also sells two CD's full of HP calculator magazine articles.

self-test

Where the calculator tests itself for any problems. This is entered on the HP48 by pressing On-D (for diagnostic) and exited by typing On-C.

serial

The HP48 has a standard RS-232 serial port, capable of interfacing with a computer with no additional hardware other than a three-conductor wire. This transmits data in serial across one sending wire and one receiving wire, one bit at a time.

SHELL OS

A replacement operating system for the HP48 written completely in assembly language. This doesn't run RPL programs, and is completely independent of the ROM.

softkeys

The six menu keys at the bottom of the screen controlled by the white top row of the keyboard, marked only with the letters A through F.

Gerald Squelart

Squelart, Gérald

One of the creators of the MetaKernel; now works for HP's ACO.

SRAM

Static Random Access Memory; this is the kind of memory that the HP48 uses.

stack

The basis for RPN, which has a multi-level (4 in older HP's and infinite within available memory in newer HP's) last in-first out (LIFO) stack. A stack, in the case of the HP48, is a variably-sized object container.

Steventon, Richard

The third co-creator of the Java stack replacement. From South Africa.

SYSEVAL

Evaluates an object at the given memory address (as a user binary integer). Be careful with this command, as random memory addresses will almost certainly corrupt memory and crash the calculator.

System RPL

Abbreviated SysRPL, this is the language most of the HP48's ROM is written in. It is also available to the user, using HP Tools (on the PC), Jazz (on the HP) or any of several other programming development tools. This the foundation for User RPL, just a lot more powerful and a lot less safe (since all protection is removed, such as argument checking).

TED

The Editor from Jazz, created by Mika Heiskanen. This uses the UFL minifont to produce 10 lines of 33 characters. TED (or ED as it is called in Jazz) is the one of the fastest editors available, and takes about 12k of memory, including the VV object viewer.

translation mode

The HP48 has three translation modes to transfer ASCII files. The translation mode determines how many of the non-standard characters are converted to (or from) plain ASCII. Translation mode three is the most comprehensive and most recommended.

UFL

Universal Font Library, a library of shared fonts (both a medium font and a minifont are available) that programs that need fast access to fonts can use. This was written by André Schoorl, and is fully customizable and used by many applications.

Usenet

Name for Internet discussion groups, called newsgroups. The HP48 newsgroup is comp.sys.hp48, and for people who don't have a news server, DejaNews archives all posts.

User RPL

The simplest programming language for the HP48, which isn't much more than a scripting language. However, although it is slow, it is still a very powerful (yet easy to use) language.

vectored enter

The ability to redefine the HP48's ENTER key, defining what it does just before the input line is parsed and right after.

warmstart

This is the equivalent of "rebooting" your HP48. All library config sequences are run and port validity is checked. The time it takes for a warmstart depends on the amount of memory and number of RAM cards. A stock G may take 2 seconds to warmstart, yet a loaded GX may take 20 or more seconds to warmstart and 3-4 seconds to turn on.

Tom Wellige

Wellige, Tom

Creator of HPShell, an HP48 program development environment for DOS.

Wickes, William

Often called the "Father of RPL," Bill Wickes contributed greatly to the HP28, of which a great amount of code was used in the HP48.

wordsize

The number of bits given for user binary integers on the HP48. The default is 64, and any number from 1 to 64 can be set.

WSLOG

Warmstart Log, giving the reasons (as a hexadecimal code) and times of the last four warmstarts.

XLIB

Name for a library command.

Xmodem

An old transfer protocol, supported by the HP48G-series. On the HP48, this is about four times faster than Kermit (or around 2400bps). However, the file name is not sent with Xmodem unlike Kermit.

Zener

A diode in the HP48 which protects the innards from stray electrical charges. If the batteries are inserted backwards, sometimes the Zener diode is fried, causing the batteries to drain within only a few days. This can be solved by removing the fried Zener diode entirely, or by sending the HP48 in for repair.

Zip

The most common compression format, originally used by PKZip and also supported by WinZip and the free InfoZip (upon which WinZip is based). This is neither the most efficient nor the fastest compression program for the PC, but it's a happy medium between the two. BZip2 could eventually replace Zip as the standard of choice with its superior compression power.