The private collection of the Dutch collector Nico Baaijens of mechanical, electro-mechanical and electronic counting, adding and calculating machines. Many pictures and close-ups.

Technical information about many calculators, including chip pinouts and self-test sequences, and patent information.

A collection of early mechanical calculating machines and other calculating devices.

An overview of the calculators manufactured by Texas Instruments Inc. from the famous Datamath (1972) to the modern Graphics calculators, with history and articles.

A library of information about the HP-41 series calculators, with emulators, publications, FAQ, and related links.

Matthias Wehrli's collection of HP calculators and accessories. Includes photographs and specifications for items in the collection.

English translation of the most important book on calculating machines "Rechenmaschinen" by Ernst Martin is illustrated on this site. The site includes .pdf version of the book, many interesting pictures of the machines, production years, and articles.

Information about every HP calculator made since 1968. Includes photo gallery, old advertisements, operating instructions, pricing information and discussion forum.

A gallery containing many varieties of pocket calculators, slide rules, and abacuses.

Photographs of the exterior and interior of many vintage mechanical and electronic calculators. Also includes vintage advertisements and technical literature.

A collection of programmable and non-programmable calculators and accessories, with articles and repair notes.

A collection of information about HP, TI and Curta calculators. Includes articles and many related links.

A celebration of old calculators showing the evolution from mechanical calculator to hand held electronic calculator.