Links go stale faster than I am able to check them. I've changed some of these links to point to the "last known good" version of the page archived at archive.org. If you run across a link that doesn't work (other than archive.org links; those can be notoriously slow and less than reliable) please let me know!

• Almetare is an open-source calculator emulator by Friedemann Seebass
• Arithmomuseum is a virtual calculator museum from Hungary
• AVASMATH 80 online programmable scientific calculator
• BASIC Comparison Sheet by Marcus von Cube
• BASIC Programmable Calculators -- Spanish-language site with a large number of manuals
• Bob's Calculators and Slide Rules
• Calculator Benchmarks using the N-queens problem
• Calculator History and Technology Archive by Alex Knight
• Calculators On-line
• The Calculator Reference by Rick Furr
• A Casio/Electronika calculator page by Piotr Piatek, with programming information and emulators for the Russian models
• Casio manuals from casiotechno.com
• Casio manuals at Casio New Zealand
• CASette IO Utilities are tools and utilities to handle tape and floppy disk images from vintage pocket computers
• Chris Woodhouse's Bring Back to HP-15C site
• Citizen calculator manuals
• The Computer Conservation Society
• Computer Museum of America
• Computers in Spaceflight: The NASA Experience includes a section on the use of the HP-41C in space
• COP444 microcontroller (used in several early National Semiconductor calculators): application notes
• CURTA Calculators
• Dan Veeneman's Calculators
• Daniel Hertrich's HP palmtop page
• datamath.org is Jörg Wörner's beautiful museum dedicated to TI calculators
• David May's Vintage Calculators
• Dimension-TI
• eCalc claims to to be the best online calculator. Best is in the eye of the beholder, but it's certainly decent.
• ELEKTRON: Electronic calculators online (Frank Boehm's comprehensive photo library).
• eMathHelp: A collection of online calculators showing step-by-step derivations
• Emilio Tozzi's programs for the Casio fx-3900Pv
• Enrico Tedeschi's Old Radio Web site
• File Save as is a site about all kinds of handheld devices
• Gary Muhonen's HP Calculators
• Handheld and Portable Computer Club
• Handheld Computer and Calculator Museum by Shinichiro Osaki
• Hans Bloemen's collection
• Historie de l'informatique: Les calculatrices programmables
• Hogan Engineering supplies civil engineering programs for the HP-48/49
• How to disassemble and clean your TI-59, by Marek Czeszek
• The (HP) Calculator Store of Jose Gonzalez
• HP Handheld Users Conference 2000
• HP vs. industry standard part numbers cross reference by Sphere Research
• HP-15C notes on hacking this calculator
• HP-41C
• hpcalc.org
• HPDATABase by Craig A. Finseth
• HPGene's HP and TI calculator page
• HPLX.NET
• HrastProgrammer's HP emulators
• International Association of Calculator Collectors
• Jake Schwartz and the PPC CD-ROM Set
• Implementation of Soviet programmable calculator architectures (in Indonesian)
• Katie Wass has several calculator manuals on her Web site
• Lawrence D'Oliveiro's TI-5X emulator
• Ledudu: Casio calculators (in French and English)
• Magyar Informatikai- és Számítógépmúzeum (in Hungarian)
• Making new HP battery packs by Douglas W. Jones
• Malcolm Talley's Web page contains valuable technical information about TI calculators, among other things
• Mathematical Resources: Calculators - links by Bruno Kevius
• Mathematics and Electronic Calculators by Alexander Bulatov
• Michael Lawrie, aka. 'Lorry', known as the operator of one of the first MUD-spinoffs, also has a museum of things electronic
• Mike Sebastian's technical information page on calculators
• Mir Kalkulatorov (World of Calculators) in Russian
• MK-152: a resurrected Soviet design?
• Mobile Computers Museum by Eiji Kako
• The Model 100 Users Group
• The Museum of HP Calculators: It all began (for me, at least) with that old HP-97 and its broken card reader that I managed to repair...
• Museum of Pocket Calculating Devices by Gerhard Wenzel
• Museum of Soviet Calculators: I first saw one over 20 years ago... one of the oddest calculators I've ever seen.
• Niederer Electronic AG
• Noël Jouenne's site, still under construction, shows some interesting vintage advertisements from the French magazine Science & Vie
• Non-HP RPN calculators
• Obsolete Computer Museum
• Office Machine Americana
• The Old Calculators Web Museum
• Oldmachines.ini.hu: Sefi számítógépei (in Hungarian)
• OpenRPN is the home of a (somewhat ambitious) public, open-hardware project to build a new RPN calculator line
• The Palmtop Network
• PC1500.com is a site dedicated to the Sharp PC-1500 and the Radio Shack PC-2
• PC-Calc is a calculator program for your desktop PC
• Peter Monta's page on calculators, and on reverse-engineering the HP-35
• Pierre Houbert's TI-58/TI-59 page and emulator
• Pocket Calculator Museum by Sinichiro Osaki
• Pocket Computer Museum: by Jean-François Laroche of France.
• Pocket Computer Museum: by Takahiro Hayashi
• POEMS/Pokemun is an emulator for SHARP pocket computers, written by Hiroyuki Kobayashi
• Programbiten Archive (in Swedish)
• Programmable Calculators (my personal collection)
• PROM Software's Sharp Pocket Computers page
• RCLcalculators is an open-source Texas Instruments (TI-58 and TI-59) calculator emulator
• The RetroCalc isn't quite "retro" for this purist's taste (there's more to old machines than just an LED display) but it's an exciting project nevertheless.
• Roy F. A. Maclean's Casio site
• A Russian calculator-based measuring system with the MK-61
• Sergei Frolov's Soviet calculators
• The secret of the algorithms: details of the CORDIC algorithms by Jacques Laporte
• Sharp Austria calculator (and other) manuals
• silrun Systems has many (mostly Casio) manuals online
• Sinclair Scientific hardware-level simulation
• Swiss Micros (formerly rpn-calc.ch) builds RPN calculators
• Taschenrechner und Kleincomputer by Martin Hepperle
• Texas Instruments calculator discussions
• TI-58/59 Hardware Annotations by Sipke de Wal
• TI-59
• TI-59 emulator (and many other programs) by Gemtree Software
• TI-Files
• The TI-TipList contains useful tips for TI-89 and TI-92 calculator owners
• ticalc.org
• TIGalaxy.com
• TiLP (formerly GtkTiLink) is an open-source, cross-platform linking program for TI calculators
• Tony Hutchins from New Zealand has a book on financial computation and many HP-200LX goodies on his Web site
• Usermanualguide.com
• Valentin Abillo's calculator pages
• Vertigo is a very good Java-based TI-59 emulator
• Vintage Calculators Web Museum by Nigel Tout
• Vintage TI Calculators forum
• The WP-34S project aims to develop alternative scientific calculator firmware for the HP-20B and HP-30B calculators
• X-Number World
• X-Ray pictures of calculators by Edward Soudentas
• Yagshi's Pocket Computers
• Yet another computer museum, at oldcomputers.dyndns.org, contains a virtual library of old computer manuals

Discussion Groups

• The Museum of HP Calculators Forum (daily view)
• Oldcalcs mailing list
• PPC-T mailing list for HP-41 enthusiasts
• Vintage Calculators Forum

Resellers, VARs, repairs, etc.

• Calcpro Online Catalog
• da Vinci Technologies Group
• Eric Armin Inc.
• FixThatCalc.com
• High Tech Solutions sells TI-74 and TI-95 accessories
• The HP Palmtop Paper: The Ultimate Palmtop Store
• International Calculator and Computer
• Jack Berg Sales calculator products
• Shier Systems and Software
• Source 4 Shopping Mall
• Underwood Distributing Co.
• Wagon Photo

Calculator Manufacturers and OEMs

• Aurex
• Aurora
• Casio Education products
• Citizen calculators
• Creative Creek: Calculator software for Palm OS
• Datexx
• Elektronika
• Hewlett-Packard
  • HP in Education Calculator Newsletter
• Karce
• Kenko
• Kinpo
• Radio Shack/Tandy FaxBack info sheets
• Sunway International
• Texas Instruments