The following links are non-HP or miscellaneous HP links that are not LCD RPN/RPL scientific calculator model related. It is a work in progress.

HP LED, Financial and Algebraic Calculator Resources:

HP-12C: The longest production run in the industry? - Forum post that describes the many HP-12C financial calculator variants. The HP-12C has been in continuous production since 1981. All 14+ hardware versions of the "HP-12C" (not counting the HP 12C Platinum) are running the exact same code base as the original HP-12C released in 1981. From 1981 to 2008, that code ran on a hardware variation of the original "Nut" processor. Starting in 2008, they have used an emulation of the Nut via ARM. In any case, they are still using the same code base developed in 1980 (the earliest S/N HP-12C known). HP-12C models produced from 1981-2008 and all HP-12C Platinum/Prestige models have their firmware in ROM and cannot be changed. HP-12C models produced from 2008-2015 have the firmware in Flash memory and can be changed. They can be flashed with the HP-15C Limited Edition firmware. These models use 3V TTL serial ports on their 6-pin POGO connectors. HP-12C models produced from 2015-Present also have the firmware in Flash memory and can be changed. They can be flashed with the HP-15C Collector's Edition firmware which has HP-15C and HP-16C firmware in it. These models use the USB protocol on their 6-pin POGO connectors. Also see the HP-12C Wikipedia page.

The Hewlett-Packard HP-12C Financial Calculator: A Contradiction of Modern Technology - Related to the above discussion.

HP-65 Training (all 3 parts) [1974] - HP Training video for the HP-65 programmable calculator (3 parts).

HP calculator reviews, teardowns and photos by MoHPC forum user Jebem - Many of the forum posts by Jebem have information on the model and many inside/outside photos of the model he is reviewing. Here are links to various HP models: HP-12C Gold, HP-12C, HP Prime Documentation, HP-27S, HP-32E, HP-35, 

HP calculator battery chargers - Has information on all HP LED calculator AC chargers. See here for information about powering the "Classic" HP LED models on the charger without batteries.

HP 10bII financial calculator - Archive of the HP website resources for the HP 10bii financial calculator. Includes training modules.

Fast and Accurate Trigonometric Functions on the HP-17BII - Provides complete trigonometric functions implementation for the HP-17BII Financial Calculator using ist Solver function.

Jacques Laporte's LED Calculator Site (archived) - An archive from the late Jacques Laporte. It includes and in-depth analysis of the hardware/software for the HP Classic and Woodstock family LED models. 

A Trip to the HP Spice Islands - Discusses the repair and upgrade of a HP-33 LED calculator.

A Spice Question - Describes how to tell tell the two HP Spice LED calculator model construction types (press fit and soldered) apart by weight. Also see HP Series Derivations and Vcalc.net.

The HP 45 complete restoration with PICTURES! -  A post by  Geoff Quickfall  showing how he restored a HP-45.

HP Classic LED replacement batteries and parts (waterhosko) - eBay seller waterhosko sells a number of replacement battery packs and repair parts for LED HP models.

HP-12C  Leather Flip Case - Leather flip case. Fits ALL HP-10C, HP-11C, HP-12C, HP-15C, HP-16C Calculators. By Chary Software.

Is the 12C SDK still available? -  A MoHPC forum post that describes programming and serial/USB interfaces on the 2008+ HP-12C models that had Flash ROM. Also applies to the HP-15C LE and HP-15C CE models that were based on these HP-12Cs. Also see related post: ARM HP-12C devkit and cable?

(17bII) Moon landing - Features a Moon Laner simulation equation for the HP-17B series Solver. This also works on the HP-19B/BII, HP-27S and Plus42 Solvers.

TI Calculator Resources:

DATAMATH Calculator Museum - The definitive site for detailed information on on all Texas Instruments (TI) calculators ever made. Also has information for other calculator manufacturers, including some HP calculators. The best reference for TI calculators on the Internet!

DATAMATH Calculator Museum Product Manuals and Product References - Contains scanned manuals for many TI brand calculators.

TI-Planet - This site contains cutting edge news on the latest calculator developments from many manufacturers including HP. TI. Casio, Sharp and more. This site has program download libraries, tools, gallery and a very nice forum and other sections. It also has a great Calculator Comparison Tool. Here is an example of a comparison of the top models from HP, TI and Casio.

TI-57 Emulator (with Original ROM and Diagnostics) - This online TI-57 emulator claims to be one of the most faithful TI-57 emulations currently available. It is also using an exact copy of an original TI-57 ROM.

TI58C Emulator - For those who do not have their own TI-58, here is a simulator for Windows.

Emulator for TI-59 Calculator - A TI-59 emulator for Android.

TI MultiView Emulators in JavaScript - This page contains online JavaScript emulators for the popular TI MultiView scientific calculator series by Texas Instruments. Includes emulation of the following TI MultiView models: TI-30X Pro MultiView (aka TI-36X Pro), TI-30XS MultiView , TI-34 MultiView  and TI-Collège Plus.  No ROMs required!

R/S Key Texas Instruments Manuals - The R/S Key Programmable Calculator site (rskey.org) has an Exhibit Hall with information on programmable calculators from many manufacturers as well as a Master Index of all calculator makers on the website.  See the Texas Instruments page for information on programmable TI models. This page from its library section has many scanned manuals for various TI models. Also see TI PPC Notes.

Datamath: Project X (TI-88) - This page tells the story of the TI-88 calculator, the unreleased high-end programmable calculator that would have been the successor to the TI-59 and anticipated competitor to HP's legendary HP-41C family. Also see the videos; HHC 2022: TI-88 Part 1: History and Go / No Go Decision and HHC 2022: TI-88 Part 2: Features, Comparisons, and Verdict by Gene Wright and HHC 2022: TI-88 Hardware Tour by Richard Nelson. The following 1982 TI-88 Program Discontinuation Memo details many of the reasons why the TI-88 was canceled. RSKey.org has a great page on the TI-88 as well.

https://ti89-simulator.com - Online simulation/emulation of the TI-89 Titanium graphing calculator.

Texas TI-66 Programmable: Toshiba skills to rescue Texas... - The MoHPC forum post features a teardown of a TI-66 with many photos. Here is the Datamath page for the TI-66.

The Great International Math on Keys Book (PDF) - A PDF of the great book that came with the original TI-30 LED calculator.

TI PPC Notes - The PPC Notes was the premier newsletter of TI calculator enthusiasts in the late 1970s and early 1980s.

Online TI-84 Calculator - Online simulation/emulation of TI-84 Plus CE and TI-30XS MultiView calculators.

Online TI 4-function Calculator Simulators - Online Javascript simulations of about 12 TI LED and LCD four-function calculators.

TI-89/89T/92+/V200 Bug List - This bug list includes bugs of the Computer Algebra System (CAS) or OS for the TI-89/89T/92+/V200 models.

TEXAS INSTRUMENTS Web Museum - A TEXAS INSTRUMENTS Web Museum site by Fabrizio. Focuses on TI calculator models but has information on some HP calculator models, watches, Mechanical calculators, computers, game consoles and many other subjects. 

TI’s answer to the HP-41C - MoHPC Forum post about the cancellation of the TI-88 calculator and why TI thought hand-held computers with programming languages such as BASIC, FORTRAN and Pascal would replace keystroke programmable calculators like the HP-41C.

Casio Calculator Resources:

2025 Casio Calculators Catalog - Casio's 2025 calculator catalog. It includes 24 models of scientific and graphical calcs plus basic calcs and desktop printing models.

KhiCAS - CAS Add-on for  the Casio Fx-9750GIII, fx-CG10/20 and fx-CG50 graphing calculators. Giac/Xcas is written by Bernard Parisse and documented by Renée De Graeve. It is related to Giac/Xcas CAS.

Compairing the fx-CG100 to the fx-CG50 - Video comparing the new Casio fx-CG100 to the fx-CG50 it is replacing. Also see: fx-CG100 Software User's Guide (English), fx-CG100 Hardware User's Guide (English), fx-CG100 Online manual, Eddie Shore's first impressions of the Casio fx-CG100.

Casio vs. TI: fx-9750GIII vs. TI84+ Graphing (video series) - These videos compare the steps and functionality of the Casio fx-9750GIII and the TI-84+ graphing calculators so that you can make an informed decision. Since the color Casio fx-CG50 is almost identical in feature set to the fx-9750GIII, these videos will also apply to compare the color Casio fx-CG50 to the color TI-84+ CE calculator.

Casio fx-CG 100 Now on Sale - Forum post about the new Casio fx-CG100 that is replacing the fx-CG50.

C.Basic - Fast BASIC language interpreter for Casio. C.Basic (Basic interpreter) runs on fx-9860G Series (SH3) or later Graphing calculators.

Casio Calculator Resources:

Sharp calculators at the Virtual Calculator Museum site -  A list of Sharp calculators at the Virtual Calculator Museum site (in Hungarian).

Notable non-HP Calculator related forum posts, articles and videos:

2015's calculator anniversary: the SR-52 - Discusses the SR-52, TI's first programmable calculator. Includes many disassembly photos and a link to a SR-52 and SR-52A Troublshooting Guide. Also see the post: SR-52A rebuild project.

Calculator Culture YouTube videos: TI - TI-58C Scientific Calculator from 1978, TI Galaxy 67 Scientific Calculator from 1992, TI-74 Basicalc Pocket Computer from 1985, TI-66 Programmable from 1983, TI-Nspire CX II CAS Calculator Review, TI-68 - Scientific calculator from 1989, TI-95 Procalc from 1986, TI-81 - Texas Instruments' first graphing calculator, TI Voyage 200 & TI 89 Titanium Graphing Calculators

Vintage Calculator Web Museum - A celebration of old calculators showing the evolution from mechanical calculator to pocket electronic calculator. 

The following three articles highlight the development of the modern electronic calculator. They are from the Articles Section of the Vintage Calculator Web Museum.

The Story of the Race to Develop the Pocket Electronic Calculator - For hundreds of years performing complex calculations was a difficult and tedious chore. Multiplication, division, and taking square roots required paper and pencil and a lot of concentration.  Some assistance became available with the invention of the slide rule and logarithm tables, and during the 20th century, the development of mechanical calculators. It was during the 1960s and early 1970s that a great revolution in calculator technology occurred.

The Arrival of the "Calculator-on-a-Chip" - During the late 1960s and early 1970s a major aim of the calculator electronics companies was to integrate all of the functionality of a calculator into one integrated circuit, so producing a "Calculator-on-a Chip". The development effort eventually led to several companies introducing, around the same time, integrated circuits that provided all of the functionality of a calculator in one integrated circuit - that is they employed a, so-called, "Calculator-on-a-chip".

The Calculator that spawned the Microprocessor: - The fascinating story of why the development of a calculator led to the development of the first commercial microprocessor, and the unexpected consequences.

Ernst Mulder's Calculator Museum - Ernst Mulder's description: Way back in the late nineties, I started this website to showcase my love of the calculators I had back then. The site was also created so that I would be able to look at them myself, and I was hoping that others would like to see the calculators as well. 

My Texas Instruments TI-66 is a Turing complete pocket minimalist computer with long battery life (video) - Video on the TI-66 programmable calculator by Abraham Moller. Be sure to look at his Programmable Calculator video playlist was well.

Non Calculator related forum sites, posts, articles and videos:

Finally! A Battery That’s Better Than Energizer and Duracell! (video) - Video that tests the following AA batteries: Duracell vs Energizer, Amazon Basics, Procell, Eveready, Varta, Panasonic, Harbor Freight Thunderbolt, Kirkland, Powerowl, Allmax, Bonai, Bevigor, Blinkspower, Ninmax, Tipsun, Enegitech, NRT, and Voniko. Batteries tested for total capacity, performance in subfreezing temperature, and fan run time. Also check out eneloop101.com for information on Panasonic Eneloop low self-discharge rechargeable batteries.

HP-71B Pocket Computer Origins and Marketing - A bit of history on the HP-71B pocket computer and examples of marketing failures.

International Slide Rule Museum (ISRM) - Contains an amazing amount of information on Slide Rules, their history and related math artifacts. It is also a great reference and timeline for the history of pocket scientific calculator models. It includes information and advertisements on various scientific calculators, primarily from 1972-1979 but also includes models up to 1991.

Dutch Circle of Slide Rule Collectors - Informational site focused on Slide Rules and spreading general knowledge and awareness of the historical importance of the slide rule.