Panasonic Model 850 Electronic Calculator
This has to be the funkiest calculator in the museum, with styling straight out of the early '70s'. The Matsushita (Panasonic) 850 (model number JE-850U, with the U designation for the US export model) is a basci four-function, 8 digit portable rechargeable battery-powered electronic calculator. The calculator was sold in Matsushita's native market (Japan/Asia) as the National Panac 850, model JE-850. Matsushita Communication Industrial Co., Ltd., used the brand name National in their native markets, and the brand Panasonic in Europe and the Americas until 2008, when it changed its name to Panasonic and consolidated all products under the Panasonic trade name world-wide.
Along with the Panasonic 850 sold by Matsushita in Japan, Olympia Werke AG in West Germany, through its long-standing OEM relationship with Matsushita, marketed the identical machine (other than branding) as the Olympia CD-80 in Europe and North America.
The Panasonic 850 is not a pocket calculator by any means, but it is a prime example of the generation of portable, rechargeable battery-powered calculators that could be operated being held in one hand, with the keyboard operated by the other hand. The machine was a little late to the class, though, as machines like the SCM Marchant I, Sharp QT-8B, Sanyo ICC-0081, and the Sharp EL-8/ Facit 1111 came before the Panasonic 850, but, it could be said that from a styling standpoint the 850 was probably the winner with its very trendy styling. It's clear that the calculators were quite popular, as quite a large number of the calculators still exist today, and can be relatively easily found on online auction sites such as ebay® and others.
The Panasonic 850 can be AC powered via an adapter (5.2V, 300mA), from a replaceable rechargeable 6V NiCd battery pack, or a battery pack that holds four AA-size dry cell batteries. The circuitry of the calculator is designed for low-power drain, to maximize the runtime on a battery power. A low battery indicator in the form of a dot in the left-most display tube lights up when the battery charge is getting low to warn the user that it's time to charge up or replace the batteries. The calculator may be operated from the AC adapter while charging the NiCd battery pack at the same time. When the dry-cell battery pack is used, the AC adapter/charger is electrically disconnected from dry-cell batteries to avoid damaging them.
The 850 uses eight individual Vacuum-Fluorescent eight segment display tubes (with the eighth segment being a small tail allowing the cross-bar to be displayed on the digit '4'). A special ninth tube, located at the left-most end of the display panel, has special symbols for error (E), negative sign(-), and low battery indication(•).
Panasonic 850 insides (from back)
The exhibited Panasonic 850 was made in the late 1972 timeframe, based on the date code of 7241 on the single Texas Instruments TMS0115NC Large-Scle Integration IC that provides the brains of the machine. The machine is very well built, obviously designed for durability, and reliability, with a very serviceable modular design. The keyboard and display assemblies plug into the main electronics board with gold-plated edge connector and socket. Gold plating was expensive, but was (and still is) the most durable and reliable material for assuring a consistent, low-resistance connection. Discrete transistors are used to drive the display. The switching power supply, located on the main electronics board, is rather complex, but was a requirement due to the efficiency needed for battery operation, as well as for generating the higher voltage needed for the vacuum-fluorescent display, as well as two voltages required for the calculator chip, from the 5 Volts generated by the battery pack. The main circuit board is very densely packed with quite a number of discrete components. The keyboard uses full-travel keys which have magnets on thier stalks that activate tiny glass-encapsulated magnetic reed switches. This type is keyboard is extremely reliable, with no concerns with switch contacts accumulating dust and grime that causes unreliable operation. A testimony to its fine design is that it still works beautifully after nearly 50 years.
Main circuit board and display module
The Panasonic 850 is not a very fast calculator. Some sacrifices had to be made in terms of operational speed in order to provide decent runtime on battery power. The faster a digital circuit operates, the more power is required, so in this machine, the Texas Instruments calculator-on-a-chip is driven at a relatively slow clock rate to minimize the power draw. The most complex operation, as with most electronic calculators, is dividing the maximum number representable by the machine by one, e.g., in this case, 99999999 ÷ 1. The 850 takes approximiately 500 milliseconds (1/2 second) to perform this operation.