The HP-41C series are programmable, expandable,
continuous memory The term continuous memory was coined by Hewlett-Packard (HP) to describe a unique feature of certain HP calculators whereby the calculator could internally sustain most, or in later models - all, of the contents of user memory (via battery-backed C ...
handheld
RPN calculators made by
Hewlett-Packard from 1979 to 1990. The original model, HP-41C, was the first of its kind to offer
alphanumeric
Alphanumericals or alphanumeric characters are a combination of alphabetical and numerical characters. More specifically, they are the collection of Latin letters and Arabic digits. An alphanumeric code is an identifier made of alphanumeric c ...
display capabilities. Later came the HP-41CV and HP-41CX, offering more memory and functionality.
The alphanumeric "revolution"
![LCD Display of HP41CX (cropped)](https://upload.wikimedia.org/wikipedia/commons/f/f7/LCD_Display_of_HP41CX_%28cropped%29.jpg)
The
alphanumeric
Alphanumericals or alphanumeric characters are a combination of alphabetical and numerical characters. More specifically, they are the collection of Latin letters and Arabic digits. An alphanumeric code is an identifier made of alphanumeric c ...
LCD screen of the HP-41C revolutionized the way a pocket calculator could be used, providing user friendliness (for its time) and expandability (keyboard-unassigned functions could be spelled out alphabetically). By using an alphanumeric display, the calculator could tell the user what was going on: it could display error messages, such as showing ("
DATA ERROR
") upon attempting to divide by zero instead of simply displaying a blinking zero; it could also specifically prompt the user for arguments ("
ENTER RADIUS
") instead of just displaying a question mark.
Earlier calculators needed a key, or key combination, for every available function. The
HP-67
The HP-67 is a magnetic card-programmable handheld calculator, introduced by Hewlett-Packard in 1976 at an MSRP of $450. A desktop version with built-in thermal printer was sold as the HP-97 at a price of $750.
Marketed as improved successor ...
had three shift keys (gold "f", blue "g" and black "h" prefix keys); the competing
Texas Instruments
Texas Instruments Incorporated (TI) is an American technology company headquartered in Dallas, Texas, that designs and manufactures semiconductors and various integrated circuits, which it sells to electronics designers and manufacturers globa ...
calculators had two (
2nd and
INV) and close to 50 keys (the
TI-59
The TI-59 is an early programmable calculator, that was manufactured by Texas Instruments from 1977. It is the successor to the TI SR-52, quadrupling the number of "program steps" of storage, and adding "ROM Program Modules" (an insertable ROM ...
had 45). Hewlett-Packard were constrained by their one byte only instruction format. The more flexible storage format for programs in the
TI-59
The TI-59 is an early programmable calculator, that was manufactured by Texas Instruments from 1977. It is the successor to the TI SR-52, quadrupling the number of "program steps" of storage, and adding "ROM Program Modules" (an insertable ROM ...
allowed combining more keys into one instruction. The longest instruction required eleven keypresses, re-using the shift keys four times. The TI-59 also made use of the
Op key followed by two digits to access another 40 different functions, but the user had to remember the codes for them. Clearly, a more convenient and flexible method of executing the calculator's instructions was needed. The HP-41C had a relatively small keyboard, and only one shift key, but provided hundreds of functions. Every function that was not assigned to a key could be invoked through the
XEQ key (pronounced ''EXEQTE'' — "execute") and spelled out in full, e.g.
XEQ FACT for the
factorial function.
The calculator had a special user mode where the user could assign any function to any key if the default assignments provided by HP were not suited to a specific application. For this mode, the HP-41C came with blank keyboard templates; i.e. plastic covers with holes for the keys, so the user could annotate customized keys. Hewlett-Packard even sold a version of the calculator where hardly any keys had function names printed on them, meant for users who would be using the HP-41C for custom calculations only (thus not needing the standard key layout at all); this version of the calculator was colloquially known, within HP's Corvallis calculator team, as a "Blanknut" (because the development code name for the HP-41C's processor was known as the "coconut").
Alphanumeric display also greatly eased editing programs, as functions were spelled out in full. Numeric-only calculators displayed programming steps as a list of numbers, each number generally mapped to a key on the keyboard, often via row and column coordinates. Encoding functions to the corresponding numeric codes, and vice versa, was left to the user, having to look up the function–code combinations in a reference guide. The busy programmer quickly learned most of the codes, but having to learn the codes intimidated the beginners. In addition to this, the user had to mentally keep function codes separate from numeric constants in the program listing.
The HP-41C displayed each character in a block consisting of 14 segments that could be turned on or off; a so-called
fourteen segment display (similar to the much more common
seven segment display
A seven-segment display is a form of electronic display device for displaying decimal numerals that is an alternative to the more complex dot matrix displays.
Seven-segment displays are widely used in digital clocks, electronic meters, basic c ...
s, which can be used to display digits only). The HP-41C used a liquid-crystal display instead of the ubiquitous
LED displays of the era, to reduce power consumption.
While this allowed the display of uppercase letters, digits, and a few punctuation characters (the
FOCAL character set), some designs needed to be twisted arbitrarily (e.g. to distinguish S from 5) and lowercase letters were unreadable (HP only provided display of lowercase letters a through e). HP's competitor
Sharp
Sharp or SHARP may refer to:
Acronyms
* SHARP (helmet ratings) (Safety Helmet Assessment and Rating Programme), a British motorcycle helmet safety rating scheme
* Self Help Addiction Recovery Program, a charitable organisation founded in 19 ...
, when introducing the
PC-1211, used a
dot matrix
A dot matrix is a 2-dimensional patterned array, used to represent characters, symbols and images. Most types of modern technology use dot matrices for display of information, including mobile phones, televisions, and printers. The system is al ...
of 5×7 dots and displayed the characters in principle as we see them today on computer screens (and, in fact, many LCD screens on various
embedded system
An embedded system is a computer system—a combination of a computer processor, computer memory, and input/output peripheral devices—that has a dedicated function within a larger mechanical or electronic system. It is ''embedded'' ...
s); this was later used by HP with the
HP-71B
The HP-71B was a hand-held computer or calculator programmable in BASIC, made by Hewlett-Packard from 1984 to 1989.
Description
Smaller and less expensive (US$595 $525 in 1984 ≈ $990 in 2005 (seInflation Conversion Factors for Dollars) MSR ...
handheld computer.
The HP-41CV and CX
Many users had used all four ports for memory expansion, leaving no room for other modules. HP designed the ''Quad Memory Module'' with four times the amount of memory, providing the maximum available memory and leaving three empty ports available. The HP-41CV (V being the
Roman numeral
Roman numerals are a numeral system that originated in ancient Rome and remained the usual way of writing numbers throughout Europe well into the Late Middle Ages. Numbers are written with combinations of letters from the Latin alphabet, ea ...
for 5) included this memory module on the main board, thus providing five times the memory of the HP-41C, and four available slots.
The internal architecture prohibited the addition of more memory, so HP designed an extended memory module that could be seen as secondary storage. You could not access the data directly, but you could transfer it to and from main memory. To the calculator (and the user), data located in the extended memory looked like files on a modern hard disk do for a PC (user).
The final HP-41 model, the HP-41CX, included extended memory, a built-in time module, and extended functions. It was introduced in 1983 and discontinued in 1990.
Programming
The HP-41C is
keystroke programmable meaning that it can remember and later execute sequences of keystrokes to solve particular problems of interest to the user. These keystroke programs, in addition to performing any operation normally available on the keyboard, can also make use of conditional and unconditional branching and looping instructions, allowing programs to perform repetitive operations and make decisions.
The HP-41C also supports indirect addressing (
computed goto
GoTo (goto, GOTO, GO TO or other case combinations, depending on the programming language) is a statement (programming), statement found in many computer programming languages. It performs a one-way transfer of control to another line of code; i ...
) with which it is possible to implement a
Universal Turing machine
In computer science, a universal Turing machine (UTM) is a Turing machine that can simulate an arbitrary Turing machine on arbitrary input. The universal machine essentially achieves this by reading both the description of the machine to be simu ...
and therefore the programming model of the HP-41C can be considered
Turing complete
Alan Mathison Turing (; 23 June 1912 – 7 June 1954) was an English mathematician, computer scientist, logician, cryptanalyst, philosopher, and theoretical biologist. Turing was highly influential in the development of theoretical co ...
. The combination of indirect addressing and gotos easily led to
spaghetti code
Spaghetti code is a pejorative phrase for unstructured and difficult-to- maintain source code. Spaghetti code can be caused by several factors, such as volatile project requirements, lack of programming style rules, and software engineers with ins ...
.
Program steps are numbered starting from 1, but this numbering has no intrinsic meaning and changes as new instructions are added or removed in the middle of a program. A special LBL instruction is used to create a label that is then referenced by the user to invoke the program, or by the program itself as target of a GTO (unconditional goto) or XEQ (execute) instruction.
Programming example
Here is a sample program that computes the factorial of an integer between 1 and 69 (70! needing an exponent greater than 99, the calculator's maximum). The integer is entered in the X register and passed as an input parameter when the program is run. The program takes up 2 registers, which is ≈14 bytes.
Step Op-code Comment
01 LBL'Fac ALPHA global label makes program callable by 'XEQ Fac'
02 STO 00 Store X=input parameter in register 0
03 1 Enter 1 in X, "lifting", or "pushing", the
stack: Y=input parameter (no longer used)
X=1
04 LBL 00 Local label for goto
05 RCL 00 Recall register 0 into X, lifting the stack: Z=input parameter (no longer used)
Y=1 or interim or final factorial
X=input parameter (N) minus effect of DSE command (-0, -1, ..., -(N-1))
06 * Multiply X and Y, "dropping", or "popping", the stack: Y=input parameter (no longer used)
X=interim or final factorial
07 DSE 00 Decrement register 0 and Skip next command when register value is Equal to 0
08 GTO 00 Go to local label 0
09 END End program - result displayed in X
FOCAL
![HP-41CV 2320S41078, - 49875764327](https://upload.wikimedia.org/wikipedia/commons/f/fd/HP-41CV_2320S41078%2C_-_49875764327.jpg)
Though the programming language used on the 41 series is a version of the keystroke programming languages used all preceding programmable HP calculators, the range of technologies, and programming-related usability and extensibility features available in 41 series models (notably keyboard overlays, a fully remappable keyboard, I/O capabilities for storing and sharing programs, and alphanumeric support), led some users to propose a new name for the language, resulting in a competition that was won by "FOCAL" for "Forty One Calculator Language".
As the name FOCAL was
already in use by the
Digital Equipment Corporation
Digital Equipment Corporation (DEC ), using the trademark Digital, was a major American company in the computer industry from the 1960s to the 1990s. The company was co-founded by Ken Olsen and Harlan Anderson in 1957. Olsen was president un ...
, the name was never formally adopted by HP.
Synthetic programming
A large users' community was built around the HP-41C. Enthusiasts around the world found new ways of programming, created their own software (such as a codebreaking game, and a version of ''
Hunt the Wumpus''
) and expansion modules, and sped up the clock (see
overclocking
In computing, overclocking is the practice of increasing the clock rate of a computer to exceed that certified by the manufacturer. Commonly, operating voltage is also increased to maintain a component's operational stability at accelerated sp ...
). Most of these activities were coordinated by the PPC club and its president, Richard J. Nelson. The PPC club published the
PPC Journal
''PPC Journal'' was an early hobbyist computer magazine, originally targeted at users of HP's first programmable calculator, the HP-65. It originated as ''65 Notes'' and the first issue was published in 1974. It later changed names in 1978 to '' ...
and produced the PPC ROM, a collection of highly optimized low-level programs for the HP-41C.
One of the discoveries of the community was that, because some FOCAL instructions were stored in memory as more than one byte, it is possible to exploit a bug in the program editor to assign strange functions to keys. The most important function was known as the byte jumper, a way to step partially through programming instructions and edit them in ways that were not otherwise allowed. The use of the resulting instructions was called ''
synthetic programming''.
Through synthetic instructions, a user could access memory and special status flags reserved for the operating system, and do very strange things, including completely locking the machine. It was possible to create sounds or display characters, and create animations not officially supported by the operating system. The system flags were also accessed as low-level shortcuts to boolean programming techniques. Hewlett-Packard did not officially support synthetic programming, but neither did it do anything to prevent it, and eventually even provided internal documentation to the user groups.
Reception
In its December 1980 issue, ''
BYTE
The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable uni ...
'' magazine described the HP-41C as "the most versatile machine ever". The author praised HP's documentation as "among the best in the industry", and reported that the calculator was "''much'' easier to program and debug" than the TI-59. Stating "I found the HP-41C far more pleasurable to program and use than its predecessors" because of its alphanumeric display, the author concluded that it was "maybe not quite" a pocket computer.
In the next issue, another author wrote that "The HP-41C ... is among the programmable calculators that lie closest to the computer borderline. It comes close enough for the jargon of computers to be useful in describing it", and praised the simplicity and reliability of the card reader and compatibility with HP-67 and HP-97 software. The review criticized the inaccuracies in calculations from the lack of
guard digits; "There is something absurd about the world's fanciest calculator not being able to give results accurate to more than seven or eight decimal places".
Hewlett-Packard responded that the alleged imprecision was inherent to arithmetic on any computer with finite precision.
Use on the Space Shuttle
![STS007-14-629](https://upload.wikimedia.org/wikipedia/commons/0/00/STS007-14-629.jpg)
An HP-41C that flew on nine early
Space Shuttle
The Space Shuttle is a retired, partially reusable low Earth orbital spacecraft system operated from 1981 to 2011 by the U.S. National Aeronautics and Space Administration (NASA) as part of the Space Shuttle program. Its official program ...
missions is on display in the
National Air and Space Museum in Washington, D.C. HP-41Cs with some special hardware configurations (the addition of
Velcro
Velcro, officially known as Velcro IP Holdings LLC and trading as Velcro Companies, is a British privately held company, founded by Swiss electrical engineer George de Mestral in the 1950s. It is the original manufacturer of hook-and-loop fast ...
strips, pre-production time module, and louder beeper, as well as the removal of parts whose
outgassing
Outgassing (sometimes called offgassing, particularly when in reference to indoor air quality) is the release of a gas that was dissolved, trapped, frozen, or absorbed in some material. Outgassing can include sublimation and evaporation (which ...
could cause contamination) were carried on early Shuttle missions for the purpose of performing mundane but necessary calculations, such as calculating the change to the center of gravity due to fuel consumption. The HP-41C was also programmed to handle calculations usually performed by the main on-board computer, such as determining ignition times for re-entry, in the case of a main computer failure.
Expandability
The functions of the calculator could be expanded by adding modules at the top of the machine. Four slots were available to add more memory, pre-programmed solution packs containing programs covering engineering, surveying, physics, math, finance, games, etc. As such, an HP-41 could in fact be tailored to the personal needs of the user. Hardware extensions included a
thermal printer
Thermal printing (or direct thermal printing) is a digital printing process which produces a printed image by passing paper with a thermochromic coating, commonly known as thermal paper, over a print head consisting of tiny electrically heated ...
, a magnetic card reader (HP-67 compatible via converter software), and a barcode "wand" (reader).
Extension modules could also add new instructions to the machine. The standard set of mathematical functions of the 41-series was somewhat limited when compared to the functionality of some contemporary HP calculators (notably the
HP-34C
The HP-34C continuous memory calculator was an advanced scientific programmable calculator of the HP 30 series. It was produced between 1979 (cost US$150) and 1983 (cost US$100).
Features Root-finding and integration
Significant to the HP- ...
and the
HP-15C
The HP-15C is a high-end scientific programmable calculator of Hewlett-Packard's Voyager series produced between 1982 and 1989.
Models
HP-15C
The HP-15C is a high-end scientific pocket calculator with a root-solver and numerical integration. ...
). Among others, the standard function set offered no integration or root-finding capabilities and lacked support for matrices and complex numbers; these extra functions could be added by an extension module.
Another module, known as the
Interface Loop allowed for connection of more peripherals: larger printers,
microcassette
The Microcassette (often written generically as microcassette) is an audio storage medium, introduced by Olympus in 1969.
It has the same width of magnetic tape as the Compact Cassette but in a cassette roughly one quarter the size. By using t ...
tape recorders, 3-inch
floppy disk drives,
RS-232
In telecommunications, RS-232 or Recommended Standard 232 is a standard originally introduced in 1960 for serial communication transmission of data. It formally defines signals connecting between a ''DTE'' (''data terminal equipment'') such ...
communication interfaces, video display interfaces, etc. The Interface Loop could also be used with the
HP-71B
The HP-71B was a hand-held computer or calculator programmable in BASIC, made by Hewlett-Packard from 1984 to 1989.
Description
Smaller and less expensive (US$595 $525 in 1984 ≈ $990 in 2005 (seInflation Conversion Factors for Dollars) MSR ...
,
HP-75
The HP-75C and HP-75D were hand-held computers programmable in BASIC, made by Hewlett-Packard from 1982 to 1986.
The HP-75 had a single-line liquid crystal display, 48 KiB system ROM and 16 KiB RAM, a comparatively large keyboard (albeit wit ...
and
HP-110
The Hewlett-Packard HP 110 (aka HP Portable and HP 45710A) is an MS-DOS compatible portable computer released in 1984. It uses a Harris 80C86 running at 5.33 MHz with of RAM. It has an 80 character by 16 line monochrome () l ...
computers.
![0978 - HP41CX Expansion Slots](https://upload.wikimedia.org/wikipedia/commons/8/8c/0978_-_HP41CX_Expansion_Slots.jpg)
HP-41 extension (or expansion) modules allowed the user of an
HP-41
The HP-41C series are programmable, expandable, continuous memory handheld RPN calculators made by Hewlett-Packard from 1979 to 1990. The original model, HP-41C, was the first of its kind to offer alphanumeric display capabilities. Later came ...
programmable calculator to extend the functionality of the machine. The HP-41 had room for up to four expansion modules at the back of calculator.
The HP-41 was not the only calculator of its generation that allowed expansion modules. The
TI-58
The TI-59 is an early programmable calculator, that was manufactured by Texas Instruments from 1977. It is the successor to the TI SR-52, quadrupling the number of "program steps" of storage, and adding "ROM Program Modules" (an insertable ROM ...
and
TI-59
The TI-59 is an early programmable calculator, that was manufactured by Texas Instruments from 1977. It is the successor to the TI SR-52, quadrupling the number of "program steps" of storage, and adding "ROM Program Modules" (an insertable ROM ...
also had pluggable ROM modules. The HP-41 modules were however much more versatile.
Memory modules (HP-41C only)
![HP-41C QUAD MEMORY](https://upload.wikimedia.org/wikipedia/commons/1/1c/HP-41C_QUAD_MEMORY.JPG)
Memory modules added
RAM
Ram, ram, or RAM may refer to:
Animals
* A male sheep
* Ram cichlid, a freshwater tropical fish
People
* Ram (given name)
* Ram (surname)
* Ram (director) (Ramsubramaniam), an Indian Tamil film director
* RAM (musician) (born 1974), Dutch
* ...
main memory to the calculator, allowing more programming steps and/or more data registers.
The original HP-41C had a main memory of 63 registers of 7
byte
The byte is a unit of digital information that most commonly consists of eight bits. Historically, the byte was the number of bits used to encode a single character of text in a computer and for this reason it is the smallest addressable uni ...
s each. Each register could hold either a number, a 6-character string, or up to seven program steps in the
FOCAL language (program steps used a variable number of bytes).
Each memory module added 64 registers, and the calculator could hold up to four of them, for a grand total of 319 registers. While this was considered huge for the time (a little more than 2
kilobyte
The kilobyte is a multiple of the unit byte for digital information.
The International System of Units (SI) defines the prefix '' kilo'' as 1000 (103); per this definition, one kilobyte is 1000 bytes.International Standard IEC 80000-13 Quant ...
s,) all expansion slots were used. User groups found a way to merge two memory chips in a single module, thus freeing two expansion slots. HP designed a module holding all four in one slot, the so-called ''Quad Memory Module''. The later HP-41CV had the quad module built-in.
Application pacs
The
ROM
Rom, or ROM may refer to:
Biomechanics and medicine
* Risk of mortality, a medical classification to estimate the likelihood of death for a patient
* Rupture of membranes, a term used during pregnancy to describe a rupture of the amniotic sac
* ...
-based application 'pac' modules added up to 4 kilobytes of read-only memory (some up to 8 kilobytes, but these were simply two independent 4K modules in the same box). Most modules held dozens of programs written in the HP-41C programming language, FOCAL.
Programs in the ROM modules could be called from a user program, using the ubiquitous XEQ function. In the program code, XEQ appeared as "
XROM
" when it was used to call a ROM program.
82104A card reader
![HP magnetic card](https://upload.wikimedia.org/wikipedia/commons/5/5e/HP_magnetic_card.jpg)
The card reader was a device able to read and write small rectangular plastic cards with two magnetic strips. The card reader could copy contents of memory onto magnetic cards, and later read back the data into memory.
As the HP-41C had
non-volatile memory
Non-volatile memory (NVM) or non-volatile storage is a type of computer memory that can retain stored information even after power is removed. In contrast, volatile memory needs constant power in order to retain data.
Non-volatile memory typi ...
(user programs and data were not wiped out when power was off) there was no absolute need for a permanent storage device, so the card reader was optional.
Each card held two strips of 112 bytes each, that could hold 16 data registers or up to 112 program steps. This limited capacity resulted in typical programs requiring five or more magnetic cards to be saved. A full backup of the machine's 319 memory registers plus internal data required 11 magnetic cards (each card had to be inserted twice.)
The card reader could read magnetic cards from the earlier model
HP-67
The HP-67 is a magnetic card-programmable handheld calculator, introduced by Hewlett-Packard in 1976 at an MSRP of $450. A desktop version with built-in thermal printer was sold as the HP-97 at a price of $750.
Marketed as improved successor ...
. HP-67 programs were translated into HP-41C instructions, as the HP-67 and HP-41 share the same programming model and operation stack. Some instructions however were specific to the HP-67, and the card reader provided additional instructions to emulate the 67.
Magnetic cards could be write-protected, and programs saved as private: once loaded back, the source code for the program could not be displayed. This made magnetic cards an obvious choice for program distribution.
However, the electric motor put a heavy strain on the calculator batteries, and the price tag for blank cards put an even heavier strain on the user's wallet.
82182A time module
The time module added a real-time clock. The clock allowed use of real-world time in programs. The user could set alarms that triggered calls to user programs. The alarms were able to switch the calculator on, so it was possible to create programs that executed at some point during the day, then switch the calculator off until the next alarm. As the HP-41 was often used as a data-gathering device in labs, this allowed the calculator to read data from monitored devices at specific times every day, without having to remain fully powered up in between readings (thus saving battery capacity).
The HP-41CX had the time module built in.
82143A thermal printer/plotter
The printer used rolls of thermal paper to print lines of up to 24 characters. The thermal paper provided for a bluish printout, but was somewhat unstable, as the printout could vanish or the whole paper turn blue due to excessive heat.
The printer had some graphical capabilities, to allow the user to design character shapes, or even turn on or off individual pixels. However, the buffer memory could not hold sufficient information to print a whole line in graphic mode, and could not alter line spacing, so it was impossible to print continuous graphics in horizontal mode. The printer, nevertheless, provided some printing utilities that were able to graph a function vertically onto the narrow strip of printer paper.
82242A infrared printer interface
Instead of using the aforementioned printer, this module could be used to interface a thermal printer with an infrared interface, namely the
HP 82240A
HP may refer to:
Businesses and organisations
* HP Inc., an American technology company
** Hewlett-Packard, the predecessor to HP Inc.
* HP Foods
** HP Sauce, formerly made by HP Foods
* Handley Page, an aircraft company
* Hindustan Petroleum
...
and the
HP 82240B
HP may refer to:
Businesses and organisations
* HP Inc., an American technology company
** Hewlett-Packard, the predecessor to HP Inc.
* HP Foods
** HP Sauce, formerly made by HP Foods
* Handley Page, an aircraft company
* Hindustan Petrole ...
. This allows for on-the-go printing without using cables - but the printer itself needs batteries as well.
82153A optical wand
![Hewlett-Packard barcode reader 'Optical Wand' for HP-41 calculators](https://upload.wikimedia.org/wikipedia/commons/f/f4/Hewlett-Packard_barcode_reader_%27Optical_Wand%27_for_HP-41_calculators.jpg)
The optical wand was a barcode reader shaped like a thick pen, and was designed to read lines of HP-proprietary standard barcodes into the calculator memory. The barcodes, printed in e.g. HP solutions books, could consist of programs, numeric or alphabetical constants, and even keypresses (letting the calculator be operated without using the keyboard) — useful for diagnosing calculators where the keyboard was suspected to be faulty.
82180A extended functions module
![HP-41C Extended Functions Memory Module](https://upload.wikimedia.org/wikipedia/commons/a/a9/HP-41C_Extended_Functions_Memory_Module.JPG)
The Extended Functions module added many functions which had long been requested by users, such as the ability to programmatically assign functions to keys, repartition memory, etc.
But the most important new function was the management of extended memory: while the HP-41C could theoretically access up
to 1024 registers, the early design limited main memory to 319 registers only. The Extended Functions module added instructions
to manage a bank of additional memory in the available addressing space of the machine. As this memory was not directly
addressable by user programs, it was seen as a set of named files containing either programs or data. Programs and data registers could
be copied back and forth from the extended memory to the main memory, where they could be accessed as usual.
Extended memory could also hold
ASCII
ASCII ( ), abbreviated from American Standard Code for Information Interchange, is a character encoding standard for electronic communication. ASCII codes represent text in computers, telecommunications equipment, and other devices. Because ...
files, and a rudimentary
text editor
A text editor is a type of computer program that edits plain text. Such programs are sometimes known as "notepad" software (e.g. Windows Notepad). Text editors are provided with operating systems and software development packages, and can be ...
was added also.
The Extended Functions module contained 124 registers of Extended memory. More could be added by ... Extended Memory modules.
The HP-41CX contained the Extended Functions module as standard.
82181A extended memory module
![0986 - HP41CX X Memory HP82181A](https://upload.wikimedia.org/wikipedia/commons/c/c4/0986_-_HP41CX_X_Memory_HP82181A.jpg)
Extended memory modules added more extended memory to the HP-41C. They required an extended functions module to be present, or the
HP-41CX version of the calculator.
Each module added 238 registers of extended memory. Up to two extended memory modules could be inserted, for a grand total of
124 + 2*238 = 600 registers. Added to the 319 registers of main memory, this covered practically all of the machine's 1024
addressable registers, for a total of 919 registers, or 6433 bytes.
HP82160A HP interface loop (HP-IL) module
''See the main article on
HP-IL
The HP-IL ('' Hewlett-Packard Interface Loop''), was a short-range interconnection bus or network introduced by Hewlett-Packard in the early 1980s. It enabled many devices such as printers, plotters, displays, storage devices (floppy disk driv ...
.''
Clones
DM41 et al.
The continued popularity of the HP-41CX among users prompted
SwissMicros
The Hewlett-Packard Voyager series of calculators were introduced by Hewlett-Packard in 1981. All members of this series are programmable, use Reverse Polish Notation, and feature continuous memory. Nearly identical in appearance, each model ...
to produce a miniature calculator approximating the size of an
ID-1 credit card (88 mm × 59 mm × 7 mm) in 2015. Named ''DM41'', it runs the original HP-41CX firmware with extended memory and realtime clock in an emulator on an
ARM Cortex-M0-based
NXP LPC1115 processor.
Deviating from the original, it comes in a landscape form factor (as known from Hewlett-Packard's
Voyager series) with rearranged keys, it features a dot-matrix display, switchable clock speeds, and, based on a
Silicon Labs
Silicon Laboratories, Inc. (Silicon Labs) is a fabless global technology company that designs and manufactures semiconductors, other silicon devices and software, which it sells to electronics design engineers and manufacturers in Internet of Th ...
CP2102 converter chip,
it comes with a
USB
Universal Serial Bus (USB) is an industry standard that establishes specifications for cables, connectors and protocols for connection, communication and power supply (interfacing) between computers, peripherals and other computers. A broad ...
(
Mini-B)
serial interface to exchange data with a PC etc. for backup purposes, to possibly communicate with applications (like PC-based emulators),
or to update the firmware. In December 2015, SwissMicros introduced the ''DM41L'', a version of the calculator about the same size as the calculators of the HP Voyager series. It still comes with a USB Mini-B connector. Since September 2020, its successor, the ''DM41X'', has also been offered with an extended range of functions and a conventional design that is very close to the classic original version.
HP41CL
In addition to clones based on emulated HP-41 hardware, there exists at least one actual hardware clone of the HP-41 series. This is the HP41CL HP-41-series CPU board upgrade created by
Monte Dalrymple at Systemyde.
The HP41CL is a ground up redesign of the components found on the HP-41 CPU board, including the CPU, which is implemented on an
FPGA and coded in
Verilog
Verilog, standardized as IEEE 1364, is a hardware description language (HDL) used to model electronic systems. It is most commonly used in the design and verification of digital circuits at the register-transfer level of abstraction. It is als ...
RTL.
The HP41CL upgrade board is made as a drop-in replacement for the HP-41 series CPU board, assuming that one has an HP-41 that has a compatible CPU board connector and a separate CPU board as well.
The upgrade comes with an over 600 register extended memory and over 320 plug-in module images.
This is possible due to the fact that the HP41CL has over 1024 pages of 4K-word flash memory built in, of which over 500 pages are pre-loaded with HP-41 software, as well as the upgrade board providing 128 RAM pages, which are made available to the user via a custom
MMU.
In addition, a "turbo" mode is provided by the HP41CL upgrade board's "NEWT" CPU design, which allows the user to speed up their calculator by a factor of around 50 times.
Also, the HP41CL maintains full compatibility with the HP-41 series bus, so that most plug-in modules can still be used in a fully backward compatible fashion.
Additionally, Systemyde makes an HP-41 compatible timer module clone as well as a
GPS
The Global Positioning System (GPS), originally Navstar GPS, is a satellite-based radionavigation system owned by the United States government and operated by the United States Space Force. It is one of the global navigation satellite sy ...
receiver interface module.
Furthermore, an optional RS-232 full-duplex serial connector (with a 2.5mm stereo jack physical interface) is available, if one has a free module slot.
Emulators
![Emulator of HP-41CX on iPhone 6s](https://upload.wikimedia.org/wikipedia/commons/9/99/Emulator_of_HP-41CX_on_iPhone_6s.jpg)
Unusually for pocket calculators, the devices still have a fan base more than 30 years after their production was discontinued in 1989. As a result,
emulator
In computing, an emulator is hardware or software that enables one computer system (called the ''host'') to behave like another computer system (called the ''guest''). An emulator typically enables the host system to run software or use pe ...
programs are available for a variety of operating systems, including
Windows
Windows is a group of several proprietary graphical operating system families developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry. For example, Windows NT for consumers, Windows Server for ser ...
,
Mac OS
Two major famlies of Mac operating systems were developed by Apple Inc.
In 1984, Apple debuted the operating system that is now known as the "Classic" Mac OS with its release of the original Macintosh System Software. The system, rebranded "M ...
,
Unix
Unix (; trademarked as UNIX) is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, an ...
variants,
Pocket PC,
Palm OS
Palm OS (also known as Garnet OS) was a mobile operating system initially developed by Palm, Inc., for personal digital assistants (PDAs) in 1996. Palm OS was designed for ease of use with a touchscreen-based graphical user interface. It is pro ...
,
Apple iOS
iOS (formerly iPhone OS) is a mobile operating system created and developed by Apple Inc. exclusively for its hardware. It is the operating system that powers many of the company's mobile devices, including the iPhone; the term also includes ...
and
Android.
[']
List of emulators for the HP-41 series
'', www.hp41.org
Images
File:0934 - HP41CX.jpg, Alphanumeric display of an HP-41CX
File:Interface loop module HP-IL for connecting HP-41 calculators with peripheral devices.jpg, HP-IL interface module
File:Thermal printer HP82162A and IL-Loop and HP41CX.jpg, HP82162A thermal printer (with HP-IL connection)
File:Digital cassette drive HP82161A for HP-41 calculator series.jpg, HP82161A cassette drive with storage medium (with HP-IL connection)
File:HP-41CX connected to thermal printer and digital cassette drive via HP-IL interface loop.jpg, Interface loop with thermal printer HP82162A (front left), a cassette drive HP82161A (back left) and an HP-41CX
File:Rear connectors of video interface HP82163B for HP-41 calculators w. TV-UHF and AV output.jpg, HP 82163B - 32 columns video interface for HP-IL
File:0978 - HP41CX Expansion Slots.jpg, Extension slots of an HP-41CX
File:0943 - HP82242A IR-Interface.jpg, HP82242A IR-interface (to a thermal printer)
File:Card reader-writer 82104A for calculator HP41C.jpg, HP 82104A - card reader/writer for HP-41C
File:0986 - HP41CX X Memory HP82181A.jpg, X Memory module HP82181A (memory extension)
File:0992 - HP41CX Stat I.jpg, Statistics module
File:1028 - HP82106A.jpg, HP 82106A memory module for HP-41C
File:1022 - HP82120A.jpg, HP 82120A battery pack for the HP-41CX with damaged NiCd cells (original)
File:0995 - HP41CX Bat Pack.jpg, HP 82120A battery pack for the HP-41CX (the original NiCd cells were replaced by NiMH cells)
See also
*
FOCAL character set
*
HP calculators
References
Further reading
*
*
*
*
*
External links
![HP41CX](https://upload.wikimedia.org/wikipedia/commons/3/3e/HP41CX.png)
*
SwissMicros DM41Xan
DM41LHP-41CL a modded version with 50x speed 120 module integratedhp41.org– A website (and domain) dedicated to the HP-41
HP41 Forumi41CX+HP-41CX Emulator for the iPhone and iPod touch
a41CVAn HP41CV simulator for the Android platform
HP-41CHP-41CVan
HP-41CXo
MyCalcDB (bilingual)(database about 1970s and 1980s pocket calculators)
with photos, documents for download, printer, card reader...
C++ (linux, QT) Source-code project.Simulator HP41CX in a nearly natural look. Based on nsim-0.61 NUT Core by Eric Smith.
clonix41.orgnbsp;- A website (and domain) with some interesting enhancements for the HP-41
{{Authority control
41
Computer-related introductions in 1979