If you remember the days when calculators were as big as today's laptops, then you'll definitely feel nostalgic when you visit the Calculator Reference. Operated by an avid collector of vintage calculators, the site covers Texas Instruments and Hewlett-Packard brands, as well as the pioneering Curta. Several other models are included in the Desktop Calculators section. Even some interesting trivia is given on the site, like why calculator key pads are numbered in a different order than telephone key pads. There are many links to other sites and articles related to classic calculator technology.