Panasonic Model 850 Electronic Calculator
This has to be the 'funkiest' calculator in the museum, with styling straight out of the early '70s'. The Panasonic 850 (actual model number is JE-850U) is a utilitarian four-function, 8 digit calculator. It appears that an identical machine was marketed by Olympia as the model CD80. I wouldn't qualify the 850 as a 'pocket' calculator by any means, as it is rather large, and surprisingly heavy. The machine is either AC powered via an adapter, or runs from a replaceable 6V NiCd battery pack. It uses a eight individual Vacuum-Fluorescent 8-segment display tubes (with the eighth segment being a small 'tail' allowing the cross-bar to be displayed on the digit '4'), and a 'custom' 9th tube for Error, Sign, and Low Battery indication.
Panasonic 850 insides (from back)
The calculator was made in late 1972 timeframe, based on the date code of 7241 on the single Texas Instruments TMS0115NC LSI IC that provides the brains. The machine is very well built, obviously designed for serviceability and reliability, with a nice modular design. The main electronics plug into the keyboard assembly with gold-plated edge connectors, and the display subassembly plugging into the main electronics board with a similar, again gold-plated, connector. Discrete transistors are used to drive the display. The switching power supply, located on the main electronics board, is also rather complex. The keyboard itself is based on full-travel keys which have magnets on thier bases which activate tiny glass-encapsulated magnetic micro-switches.
Main circuit board and display module
The machine runs rather slowly, with 'long' (IE: 99999999/1) divide operations taking up to 1/2 second to perform.