Making the most of your HP calculator


Home Club Calculators Handhelds Magazine Discussions


Introduction Principal Features Emulators Availability Books Datafile Articles Links


Described in one HP brochure as "Unsurpassed in terms of software, expandability and versatility, these are the calculators that grow with your needs." The HP41 series of calculators were considered by many people to be the ultimate calculator. They sold in massive numbers, had vast software support, spawned user groups like HPCC and were even used on the Space Shuttle.

The HP-41C was launched in 1979 and was a quantum leap over previous programmable calculators due to its alphanumeric capabilities and unique user interface. It had 63 registers which could be divided up between program space and storage space. Single memory modules adding blocks of 64 registers were available allowing up to a maximum of 319 registers but doing so prevented the user adding ROMs or peripherals. The 4 expansion slots could be utilised to drive a printer or accept printed programs from barcode or allow the addition of a magnetic card reader.

HP's first attempt at correcting this problem was the Quad memory module which allowed full expansion of user memory whilst using only 1 slot. A better solution came in the form of the HP-41CV which had the full 319 registers built in.

The addition of the HP-IL interface loop allowed the addition of printers, digital cassette drives, plotters, multimeters, modems, video interfaces and a host of other peripherals whilst only occupying 1 slot. This left the other slots for ROM modules which could contain programs on virtually every (mathematically based) subject you could think of.

Perhaps the most interesting HP produced modules were the Time module and the Extended Functions module. Amongst other things the Time module allowed alarms to wake up the calculator and run programs allowing for example the system to become a control unit in data collection applications using inputs from devices connected to the HP-IL system. The Extended Functions module provided a RAM disk system allowing program and data files to be stored and manipulated in extended memory (some of which was included in the module). HP supplemented this with additional Extended Memory modules providing additional non-volatile storage on the machine.

The HP-41CX then came out containing the capabilities of the HP-41CV plus the Time and Extended Functions modules plus some other unique features like a Text Editor for ASCII files in extended memory.

HP also ensured that the HP41 remained competitive against newer more mathematically powerful calculators by bringing out the Advantage Module which added some of the financial functions of the HP-12C, complex number and matrix handling like those on the HP-15C and computer science funtions like those of the HP-16C. When the next generation of calculators added Infrared printer support, HP brought out the "Blinky" module.

Finally discontinued with the introduction of the HP48SX the HP41 series remains a testament to the people who developed it. A classic in its own lifetime.

Many more details of the HP41 series can be found in the HP Calculator Museum.

Principal Features

  • Up to 6.4K RAM
  • Up to 24K ROM built in
  • 12 character high contrast alphanumeric LCD
  • 4 expansion slots allowing additional RAM/ROM or external devices
  • Reverse Polish Notation
  • Completely customisable keyboard
  • Backwards compatibility with HP-67/97
  • Key programmability
  • Over 30 ROM modules available
  • Numerous printer options
  • Numerous mass storage options
  • Optional bar code reader to save typing in programs from Solution Books and calculator club magazines


The HP41 series was so popular that emulators are available to run on the HP48 series, PCs and Pocket PCs. Look in the links section below or on www.hp41.org and www.hpcalc.org.


HP-41C Introduction-Discontinuation: 1979-85
HP-41CV Introduction-Discontinuation: 1980-1990
HP-41CX Introduction-Discontinuation: 1983-1990

These machine are now quite sought after and consequently prices are reasonably high although bargains can sometimes be found on the comp.sys.hp48 newsgroup. HP-41 models are occassionally sold in the For Sale & Wanted column of Datafile and on eBay.


Contact Wlodek to order books. HPCC members can find ordering details and a full book list in the Memberpack.

Extend Your HP-41 by W.A.C. Mier-Jedrzejowicz

A very detailed book (sometimes called the HP-41 encyclopaedia!) about the HP-41 handheld calculator/computer, still popular in some applications. 20, postage in the UK & Europe 4. Few remaining.

Datafile Articles

EMU41 Update 2006 - HP41 to EMU41 on a PC via RS232Christoph KlugV25N3P18
HP41 to another HP41 via RS232Christoph KlugV25N1P18
HP41 and EMU41 Uploading ROM plug-in modulesChristoph KlugV22N6P38
HP-41 - PC Gateway & EmulatorChristoph KlugV21N6P36
Interfacing IL2000 System to Analogue WorldChristoph KlugV20N3P29
IL2000 Interface SystemChristoph KlugV19N3P14
HP-41 Hardware Interface ActivitiesChristoph KlugV19N1P31
HP-41 Input/Output-BoardChristoph KlugV18N4P30
Audio Measurement with HP-41Christoph KlugV17N6P41
Machine Code Debugger ROM, Quick Reference Guide and User Guide Source Code Mark PowerTBC


HP41 Quick Reference (from the Wayback Machine)
HP41 Programs and information (from the Wayback Machine)
HP41 Hardware Activities and Interfacing
HP41 HP-IL LIF File Utilities (for Linux)
HP41 Emulator (and other development tools/documentation)
HP41 Use on the Space Shuttle
HP-41C/CV/CX MicroCode Emulator (for HP48/49)
NEWT Microprocessor and 41CL Calculator Status Page (HP41 being rebuilt from scratch)  - NEW

Page last modified : 18th February 2017