Hewlett Packard HP-41C/CV/CX/CL

Serial Number 2340S40265, 1983 Singapore
Accessories Pouch

Quad memory module 82170A, s/n 2215 installed (made in Singapore)

Manual: "Bedienungs- und Programmierhandbuch HP-41C" (German, 260 pages, Printed in USA, August 1978)

Manual: "HP-41C/CV Handbuch für den fortgeschrittenen Anwender" (German, 73 pages, Rev. B, September 1981, printed in Singapore)

Quick Reference Card: "HP-41C Kurzanleitung" (German, 18 pages, printed in USA 6/1997). With a mark "Dieter Lange Netzwerke GNAP LNAP" on the backside. Apparently, GNAP & LNAP refer to some HP-41 keyboard overlays.

Quick Reference Card: "The HP-41C Quick Reference Guide" (English, 15 pages, printed in USA 1/1979)

Power supply, 220V. Apparently broke at some time because the enclosure is glued.

Thermo-Printer 82143A, s/n 2343S30014 (1983 Singapore), one roll of paper installed. Excellent condition, fully functional.

Manual: "82143A Thermodrucker Bedienungshandbuch" (German, 88 pages, August 1979, printed in Singapore)

Quick Reference Leaflet: "Thermodrucker HP 82143A Kurzanleitung" (German, printed in Singapore). Interestingly, the "print stack" command is listed incorrectly as "PRST". In the manual it is noted correctly as "PRSTK".

Cardboard box with 6 rolls of paper for the 82143A or 82162A printer. Order number 82174A. Excellent condition.

Original HP-41C cardboard box in good condition. One one side marked "00746".

Magnetic Card Reader82104A, s/n 2036S45359 (1980, Singapore).

Manual: "HP 82104A Magnetkartenleser Bedienungshandbuch" (German, 72 pages, printed in Singapore, September 1979)

Manual: "HP-41C Standard Programmsammlung" (German, 60 pages, printed in Singapore, August 1980)

Quick Reference Card: "HP 82170A Memory Module For the HP-41C" (English,  printed in Singapore, June 1983)

Envelope marked "Wichtige inliegende Garantiekarte" (Important Information Enclosed", "HP-41C Accessories" leaflet (multi-labguage), Postcard "HP Programm-Bibliothek Europa", Postcard "System HP-41C Service Karte/System HP-41C Service Information" (dated 3/1980), Postcard (punch-card) "HP-41C Mitgliedskarte" addressed to HP Switzerland/Geneva.

One blank overlay, one standard functions overlay (both plastic)

One sheet of sticky labels for overlays, completely new.

Magnetic program card holder with 39 unmarked magnetic cards. The card holder itself is marked "HP 41 CX Inhaltsverzeichnis VBSG-Fahrzeiten". "VBSG" potentially refers to the "Verkehrsbetriebe St. Gallen" (Switzerland).

Magnetic program card holder with 38 unmarked magnetic cards and one red card used to clean the magnetic head of the card reader.

Empty module holder pouch.
Condition Absolutely excellent! Front and back close to mint, a few scratches on the sides.
Acquired 18.6.2008
Serial Number 2003A01665: 1980, 3rd week, America
Accessories Pouch

Manual: "Bedienungs- und Programmierhandbuch HP-41C" (German, 260 pages, dated 8/1997)

Manual: "HP-41C Standard Programmsammlung" (German, 59 pages, dated 8/1979)

Plastic envelope for three memory modules

Powersupply: "Netzteil 2800 HP-41c". Rather large with no other markings.
This early HP-41C unit is equipped with golden ball-contacts for the external power supply. Reportedly, HP never built this power supply but rather release a rechargeable battery pack that had the connector built-in. This power supply was built by a German company called Craesmeyer according to the label on the back of the circuit board (possibly located at Borchenerstraße 16 in Paderborn). Also, there isa label reading "3403".

Two keyboard overlays: One with standard key symbols, one with no labels.

Sheet of small adhesive labels with programming functions.

Quick Reference card: "HP-41C Kurzanleitung" (German, 18 pages, dated 6/1979)

2 memory modules with 2 instruction pages (printed 6/1980, German and Swedish).

Machine-readable "HP-41C Mitteilungskarte" addressed to "Hewlett-Packard SA" Meyrin/Geneva, Switzerland (German).

"System HP-41V Service-Karte" (German)

Leaflet "HP-41C Accessories" (multi-lingual)

Original cardboard box
Condition Pretty good. No scratches on the back, keys feel a bit worn from extensive use, front dirty (seems someone glued a keyboard overlay to the unit.) Unfortunately, my cleaning efforts made things even worse (not visible on the picture).
Acquired 12.7.2007
Serial Number 2153S40650: 1981, 53th week, Singapore
Accessories Pouch

Battery pack

Manual: HP82104A Card Reader Owner's Handbook, bound printout from the MoHPC CD-ROM

Manual: HP-41/41CV Owner's Handbook And Programming Guide, bound printout from the MoHPC CD-ROM

Manual: HP-41C Quick Reference Card For Synthetic Programming, durable plastic

Approx. 160 magnetic cards in four program card holders. Some listings included
Condition Mint calculator. Note that two extension port covers have been marked with a black pen (hardly noticable).
Acquired 5.6.2002
Serial Number 2819S20526: 1988, 19th week, Singapore
Accessories Manual: HP-41CX Owner's Manual, Vol. 1, still sealed

Manual: HP-41CX Owner's Manual, Vol. 2, still sealed

Manual: HP-41CX Quick Reference Guide, August 1984

White keyboard overlay with normal function codes

Black "STOP WATCH" keyboard overlay

Pouch with foam insert

Cardboard box, a bit shelf worn

Additional 75 Magnetic Cards

Manual: HP 82180A Extended Functions/Memory Module Owner's Manual, Sept 1985 (PDF), bound printout of the MoHPC CD-ROMs

Manual: HP 82182A Time Module, May 1982 (PDF), bound printout of the MoHPC CD-ROMs
Condition Mint out of the box, everything like new except the cardboard box
Acquired 1.9.2002
HP-41CL A HP-41CV with a new NEWT hightech motherboard.
Serial Number 2436S43963: 1984, 36th week, Singapore
Accessories Pouch with foam insert

Serial cable
Condition Mint
Acquired 13.11.2013

Card Reader
HP-41 Magnetic Card Reader, No. 82104A
Serial Number 1954A00955: 1979, 54th week, USA
Batteries None (powered from HP-41 calculator)
Repairs 26.6.2002 Card reader works 2 or 3 times and then dies with a gooed-up transport wheel. Replaced the rubber wheel - now it doesn't work any more at all! 
27.7.2002 Another attempt: This time I didn't install a little spring which obstructed the card slot - now it works!!
Did not put back the label which covers the screws.
Acquired 19.6.2002
Magnetic Cards
About 70 magnetic cards for the magnetic card reader
Acquired 1.9.2002
Manual Manual: 82104A Card Reader Owner's handbook

English, Rev. B 11/79, 70 pages
Acquired 11.12.2003, currently stored with HP-41CV s/n 2153S40650
Barcode Wand
HP-41 Bar Code Reader Wand, No. 82153A

Manual: HP 82153A Bar Code-Leser Bedienungshandbuch (German), dated Jan 1980
Serial Number 2055
Batteries None (powered from HP-41 calculator)
Condition Both reader and manual in excellent condition. Works flawlessly.
Acquired 22.3.2003, currently stored with HP-41CV s/n 2153S40650

Printer HP-41 Printer, 82143A
Serial Number 2211S87228: 1982, 11th week, Singapore

Manual: 82143A Thermodrucker Bedienumgshandbuch (German, 88 pages, dated Feb 1982)

Quick Reference Sheet: Thermodrucker 82143A Kurzanleitung (German, 12/1981)

3 rolls of printer paper
Batteries Large battery pack or external power supply
Condition Mint! Fully functional.
Acquired 12.11.2003, currently stored with HP-41C s/n 2340S40265
Book PPC ROM User's Manual

English, approx. 500 pages
(C) PPC 1981, Santa Ana, California, USA

Bound printout from the pages at hp41.org including "PPC ROM Manual Corrections"

Book Best Of Prisma, CCD - Computerclub Deutschland e.V.
German, 245 pages, 1st issue, 1986
Tips&Tricks, Barcode-Programme, Synthetik, Mathematik, Plotprogramme, Elektrotechnik, Spiele, Sonstiges
27.5.2003, currently stored with HP-41CV s/n 2153S40650

Book W.C.Wickes: Synthetische Programmierung auf dem HP-41C/CV, Heldermann press, Berlin, 5th edition

German, 137 pages, 1982. ISBN 3-88538-800-6
Various information on "synthetic programming".
29.12.2003, currently stored with HP-41CV s/n 2153S40650

ROM Module
Math 1 ROM module, part no. 00041-15003, serial no. 2016

2 keyboard overlays (numerical integration, coordinate transformations)

HP-41C Math Pac, Instruction manual (English), dated 1979

HP-41C Math Pac I Quick Reference Card (English), dated 1979
Functions Matrix operations, Root finding, Polynomial solutions & evaluation up to degree 5, Numeric integration, Differential equation solver for 1st and 2nd order equations, Fourier transformation, Complex operations, Hyperbolic functions, Triangle solutions, Coordinate transformations
Acquired 22.3.2003
IR Module
Infrared module HP-82242A, serial number 2943.

Manual: HP-82242A Infrared Printer Module Owner's Manual (English, bound printout of MoHPC DVD, 95 pages)
21.1.2004, currently stored with HP-41CV s/n 2153S40650

QuickRef Card
HP-41C Quick Reference Card, for synthetic programming
(C) 1982 Synthetix, California
Acquired 2003, currently stored with HP-41CV s/n 2153S40650

Picture of various accessories

Keyboard overlay for the stopwatch module
Book HP-41 in der Praxis (German), 1985, Vieweg Programmbibliothek, Mikrocomputer 21, ISDN 3-528-04347-4
Contains less useful program examples from Physics, Math, Finance, Printer apps, Games.
Acquired 5.6.2002
Manual Manual: HP-41 Advantage, Advanced Solutions Pac.
English, dated July 1986, 155 pages, bound printout from the MoHPC DVD PDF.
HP codename, series
Silverbird Honeynut or Halfnut (reduced electronics)
Series Coconut
Type, Precision, Input Mode Scientific, 10 BCD digits, exponent ±99, Reverse Polish Notation.
Delivers highly accurate results!
Programmable Yes, merged keystrokes. Memory space is shared between programs and data storage, allocation is performed using the SIZE command.
One register can hold up to 7 program steps (7 bytes).
Labels 00-99 and mutli-character string labels. Named programs.
Labels A-E and a-e could be assigned to top row function keys to mimic HP-65/67.
Performance Index
HP-41CL (50x)
It is not quite clear why the 41C is faster than the CV and CX. Maybe branching to labels takes longer if more memory has to be searched for a label.
Memory Permanent memory. Register memory shared with program memory.
Data registers >99 can only be addressed indirectly.

Total registers 63 register
319 register 319 register
Extended memory
126 register
Default configuration

322 program steps (46 register)
17 data register
322 program steps (46 register)
273 data register
1533 program steps (219 register)
100 data register
Memory extensions
4x regular module (64 register each) - or -
1x quad module (256 register)

2x X-memory module (238 register each)
Maximum memory
319 register (2233 bytes)
319 register (2233 bytes) 821 register (5747 bytes)
HP-41C Memory Modules:
The HP-82106A memory module added 64 registers. Up to four such modules could be added to reach a total of 319 registers.
The HP-82170A quad memory module added 256 registers giving a total of 319 registers. Only one such module could be installed.
HP-41CX Extended Memory:
Data inside extended memory is organized in files which can store programs or data. To execute a program in extended memory it must first be copied to regular internal memory.
HP-41CX Memory Modules:
The HP-82181A "X-memory" module increased the extended memory space by 238 registers (1666 bytes).
Apparently, only two such modules could be installed.
Presumably, X-memory modules could not be installed in the HP-41C/CV.
Display 12 digit 14 segment black&white LCD for alphanumeric display
Special features A very popular calculator. Allowed for "synthetic programming" where machine code was accessible thru illegal commands. Expansion ports for additional RAM or ROM code; ROM could be self-made with special programming tools. All keys could be re-assigned to user-defined commands. The "flying goose" and the "backwards flying goose".
Works with the HP Infrared Printer provided an IR module is installed.
With a HP-IL module installed this unit could access a wide range of HP-IL I/O devices, printer, video grabber, tape recorder, serial port, general purpose I/O, and much more.

A HP-41C with more memory.
HP-41CX A HP-41CV with added extended memory, a built-in timer module and the extended functions module.
Original Pricing, Production
HP-41C 1.7.1979 ($295) - 1.1.1985 ($195)
HP-41CV 15.12.1980 ($325) - 11/1990 ($175)
HP-41CX 1.10.1983 ($325) - 11/1990 ($249)
Batteries 4x type "N" or power supply with special adapter.
Note that the printer 82143A can power the HP-41.
Dimensions Length 14.3cm, Width 7.8cm, Height 3.1cm
Links (local) HP-41C/41CV Owner's Handbook and Programming Guide (PDF, English, 282 pages, 9/1980)
HP-41C/CV Operating Manual, A Guide for the Experienced User (PDF, English, 76 pages, 9/1980)
HP-41CV Quick Reference Guide (PDF, English, 11 pages, 5/1984)
HP-41CX Owner's Manual, Volume I: Basic Operation (PDF, English, 148 pages, 10/1983)
HP-41CX Owner's Manual, Volume II: Operation in Detail (PDF, English, 312 pages, 10/1983)
HP-41CX Quick Reference Guide (PDF, English, 21 pages, 8/1983)
Available Accessories.
HP-41 Command Reference (PDF)
Card Reader Usage Example.
Further Information (restricted)
HP-IL Info (Dan McDonald, restricted)
Extend you HP-41 (PDF, by W.A.C. Mier-Jedrzejowicz, 707 pages, 2nd edition 1985, ISDN 0951073303)
HP-41C Alphanumeric Programmable Scientific Calculator SERVICE Manual, PDF, July 1979, 45 pages
Hewlett-Packard Journal March 1980, PDF, 32 pages
Links (external) NutEm Coconut Emulator (Mike)
HP41.org (Lots of useful documentation)
HP41.org/HPIL (HP-IL Information including manuals)
HP-41 onboard the Space Shuttle (Smithsonian)
HP-41 Pages (Meindert Kuipers)
HP-41 Page (Dan Pfeiffer)
HP-41X Emulator (HrastProgrammer)
Homepage (Jean Francois Garnier)
HP-41 Emulator Page (Alvaro Gerardo Suárez)
HP-41CX Emulator for Palm Pilot (Bernd Abel)
HP-41CV Emulator for Palm Pilot (Charles Lee)
PPC ROM Manual (hp41.org)
Creating barcode listings (MoHPC)
Finseth's HP-41 page (describes software bugs of early versions)
Forensic Result 9.000417403 obtained from a HP-41CX
Comment The HP-41C was Hewlett Packard's first and the HP-41CX the last Honeynut model. A calculator with cult status. Especially the possibility to access ROM code made it the preferred toy for "hackers". Different from all the Woodstock, Spice, Voyager and Pioneer models and similar to the HP-65/HP-67 it could store programs on magnetic cards. A unique feature was the barcode reader "wand" that allowed to read in programs that were printed on paper in the form of barcodes. This code-exchangability created a huge base of programs. Also, HP provided a respectable number of software packages as well as ROM modules with pre-programmed solutions.
Another important feature was the HP-IL module that provided a convenient way to connect a large number of I/O modules just like with the HP-71B and HP-75.
It is also one of the first calculators with support for alphanumeric strings - but in my opinion this makes the display hard to read. The graphics display of some of the Pioneer models is much better in this respect. 
There's not much built-in functionality like the solver and integration module of the HP-15C or HP-32SII. And although it looks modern it is rather slow.
In 1988 HP released the HP-42S which was designed to be code-compatible with the HP-41. Unfortunately, it lacked all of the HP-41's I/O features.
Other HP-41 models:
  • HP-41CY TURBO:  6573 bytes of RAM (939 register) and a doubled clock speed. See HP-Collection.
  • HP-41 Option 001: Without most of the keyboard labels, to be used with keyboard overlays. See RSKEY.ORG.

Some Basic Usage Instructions

XEQ ALPHA string ALPHA To enter commands that are not directly accessible thru the keyboard use the ALPHA input mode. Refer to the table on the back of the calculator for special keys (ie. "$", ">", "/" etc.).
For plain string input do not use XEQ.
SIZE nnn Specifies the amount of number registers nnn to allocate. The remaining registers can be used for program code. To enter this command press: "XEQ ALPHA SIZE ALPHA". The display will indicate "SIZE _ _ _" and wait for the three digits to be entered.
Note that registers >99 cannot be directly used with STO & RCL. Rather, indirect access must be used.
PRGM GTO . . A "GTO . ." in programming mode jumps to the beginning of the program memory and displays the amount of available program registers, ie. "00 REG 46". The amount of number registers can only be found out by trying per STO or RCL. "NONEXISTENT" is displayed for registers that are not available. 
Reset To reset the HP-41 turn off unit,  press and hold ENTER and back-arrow, press ON and release all keys. Older units will be completely reset, newer units perform a "soft reset".
Programming/Labels A program must start with a global label which is an ALPHA string with at least two characters or a character K - Z or k - z.
Within a program local labels 00-99, A - J and a - j can be used. These local labels are not visible outside of the current global program.
When "USER" mode is active, pressing A - J or a - j  (more precisely: one of the two top row keys, either directly or shifted, ALPHA mode is not needed here) then the calculator looks for this local label in the current program and starts execution there.
WARNING: You can enter a program that starts with a local label. However, after the focus moved away from this program (ie. by executing another program) you cannot easily access this program any more!! A GTO to the local label or an XEQ will fail with NONEXISTENT. Also, it is not possible to use "CLP" to delete the memory occupied by the program! The only way to move the focus to this "hidden" program is to use "CATALOG 1" and carefully watch for an "END" that is not preceeded with a global label. After the listing has been stopped when this "END" is displayed switching to PRGM mode will display the program and it is possible to delete it step-by-step to reclaim program memory.
Speed test programProgram "ST" (speed test) is the core speed test program. "SW" (speed wrapper) is a wrapper program which executes the speed test program as many times as register 03 speifies. See Performance Index.
01 LBL "ST"
02 10
03 STO 00
04 LBL 01
05 1
06 +
07 4.567E-4
08 -
09 70
10 +
11 69
12 -
13 7
14 x
15 11
16 /
17 RCL 00
18 1
19 -
20 STO 00
21 x<>0 ?
22 GTO 01
23 Rv
24 log
25 sin
26 sqrt
27 sqrt
28 RTN
01 LBL "SW"
02 LBL 00
03 XEQ "ST"
04 RCL 03
05 1
06 -
07 STO 03
08 x<>0?
09 GTO 00
10 RTN
 Execution timeSpeed test results
With Turbo off
12.5 sec for "ST"2.7
With 50x Turbo
10.5 sec for "SW" with 20 loops64.7
= 24x normal speed


For those who need more MIPS in their HP-41 look at the 41CL Calculator, Mr. Monte J. Dalrymple has designed a new circuit board for the HP-41 housing which is equipped with a "NEWT" (Nut, Expanded, With Turbo) micro processor. The NEWT can be up to 50 times faster than the original "Nut" processor in the HP-41.
LinksThe following files are available on the Systemyde website:
HP41CL Manual, PDF, 2013, 124 pages, including memory reference
CLUTILS Module, for rev. 2.H.01, PDF, 22.1 2012, 36 pages
POWER_CL Module, for rev. 4J, compilation revision 4.W.5.6, PDF, June 2013, 112 pages
NEWT Microprocessor Technical Manual, PDF, 2.8.2013, 164 pages

A note from José González Divassón from Thecalculatorstore, where I bought the HP41CL:
"Sometimes, maybe after a shock, it will look like all your modules have been lost, and that you need to reinstall everything (as if the memory had erased). It has not. I have a couple of CL myself, and it has happened that once per calculator so far.
You just need to re-enable memory management (XEQ MMUEN) and everything will be where you left it!"

A picture of the serial interface connector.

Calculator Precision

Correct result
HP-41CX Result
2^40 / 1E12 
sin(0.01 rad)*1000 
sin(1 rad)*10 
sin(1.5608 rad)*10 
sin(800 rad)*10 
tan(0.01 rad)*100 
tan(1 rad) 
tan(1.5708 rad)/1E5 
tan(800 rad) 
sin(0.01 deg)*10000 
sin(50 deg)*10 
sin(89.9 deg)*10 
sin(5000 deg)*10 
tan(0.01 deg)*10000 
tan(50 deg) 
tan(89.99 deg)/1000 
tan(5000 deg)*10 
asin(0.01 deg)*10 
asin(0.5 deg)/10 
asin(0.999 deg)/10 
asin(0.99999 deg)/10
atan(0.01 deg)*10 
atan(0.9999 deg)/10 
atan(1.0001 deg)/10 
atan(1E4 deg)/10 
+5.555555555 555555556
+4.444444444 444444444
+3.086419135 802500000
+4.450000000 000000000
+1.414213562 373095049
+1.005012520 859401063
+2.718279110 178575917
+2.718284546 742232836
+2.688117141 816135448
-1.381551055 796427410
-5.001250416 822979193
+4.998750416 510479141
+1.011579454 259898524
+9.999769744 141629304
+1.000023026 116026881
+1.258925411 794167210
-7.698970004 336018805
-2.172015458 642557997
+2.170929722 302082819
+6.000043427 276862670
+1.099511627 776000000
+2.718856483 813477575
+2.718280469 319376884
+9.999833334 166664683
+8.414709848 078965067
+9.999500371 413582332
+8.939696481 970214179
+1.000033334 666720637
+1.557407724 654902231
-2.722418084 073540959
-1.994900160 845839293
+1.000016667 416711313
+5.235987755 982988731
+1.526071239 626163188
+1.566324187 113108692
+9.999666686 665238206
+7.853481608 973649763
+7.854481608 975316429
+1.570696326 795229953
+1.745329243 133368033
+7.660444431 189780352
+9.999984769 132876988
-6.427876096 865393263
+1.745329269 716252907
+1.191753592 594209959
+5.729577893 130590236
-8.390996311 772800118
+5.729673448 571526491
+3.000000000 000000000
+8.743744126 687686209
+8.974376527 084057279
+5.729386976 834859268
+4.499713506 778012245
+4.500286464 574097998
+8.999427042 206779036
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