The Museum of HP Calculators 
Displays and describes Hewlett-Packard calculators introduced from 1968 to
1986, as well as information about slide rules, planimeters, calculating
machines, and early electronic models. Features sections on collecting, buying and selling, repairing, documentation, and related links.
Calculating machines
This site deals with the mechanical calculating machines from a collector's point of view. There is a chronological description, pictures, and various reference links to organizations, and books.
Calculator history
Presents a historical timeline of Texas Instrument's calculator events.
Calculator reference page
This page is part of the Museum of HP calculators site and provides many references to HP calculators, older computers and scientific instruments, books, and other reference materials.
Early Calculators
Contains information about slide rules, planimeters, calculating machines, and early electronic models. This page is hosted by The Museum of HP Calculators site.
Multipurpose Windows shareware calculator
Describes the features of UCALC, a multipurpose calculator program that evaluates expressions, solves and plots equations, and imports data to plot.
Sharp Electronics Calculators
Product page highlighting Sharp's line of printing, scientific and graphing calculators.
Texas Instruments calculator home page
This Texas Instruments calculator, databanks, and organizers page provides links to product and support programs and news. There is also a link to calculator history.
ticalc.org graphing calculators site
The ticalc.org project is a collaborative effort geared toward the numerous fans of Texas Instruments' graphing calculators.The site provides comprehensive information on various models of those calculators, a buyers guide and a FAQ.
Yahoo!'s HP calculators page
Yahoo!'s directory of HP calculators.
Yahoo!'s Texas Instruments calculator page
Yahoo!'s directory of Texas Instruments calculators.