Purchased as part of the lot of 24 calculators and organizers for $9.99 with $7.70 shipping. Photos Large, back with storage compartment, circuit board, light, display. Put back the seal after battery replacement.» This organizer was one of about ten purchsed in the same lot referred to above. The batteries leaked, but it still works. I’ve included it in the calculator museum since, while it does not calculate numbers, it is based on the same technology.
Unlike a calculator, at least one of these batteries draws some power all the time to keep the memory alive. Also, Vintage Calculators lists it as having a yellow screen, while mine does not have the yellow filter indicating the calculator may have changed slightly over time. Commodore 798A, LED calculator with memory and square root. Casio Memory 8R, (1975 Japan) horizontal design, purchased on eBay on 5-22-05 for $2 ($3.50 shipping). Keys and logic in good working condition. According to an HP article on RPN, RPN has several advantages over typical algebraic entry including showing intermediate answers and using fewer keystrokes. HP says it’s easy, and now even has a virtual RPN calculator at the above link to try it out. Sharp Calculator Watch, purchased new on eBay in March 2005 for $11. With the advent of LCD displays calculator watches were developed. I find them to be curious but not very practical since the buttons and display are so small it is difficult to use.
Note the beautiful white, gray and green motiff (although it is not purple or lime green). TI 81 with View Screen, the first Texas Instruments graphing calculator. This ingenious design dates back to 1885. This Model J according to the serial number was made in 1926. The Model Js are the only model with a letter in the serial number — J obviously. The manual is available online as a pdf document at . TI 5142 III, 1983 desktop calculator with printing tape and fluorescent display manufactured in Japan by Toshiba according to .