Commodore 500E Vintage Calculator 1967 Nixie Tubes

Description

A part of the first wave of all electronic desktop calculators, the Commodore 500E is a licensed, rebranded version of the Casio 101E. Both of these calculators are incredibly complex machines, introduced just before the invention of 'Multiplexing', allowing one set of transistors to process and display the digits in sequence, each of the Nixie tubes that make up the display have independent circuitry; leading this machine to have an astounding 9 plug in circuit boards in addition to 3 hard wired boards. Besides the 9 plug in boards with edge connectors,
many of the features of this very advanced for the time calculator were achieved through a painstakingly hand soldered nest of jumpers and ribbons and patches. Even the keyboard has each key independently hardwired to it's own circuit, which are then in turn hardwired to the backplane for redistribution to the other boards (which were 12" x 7" beasts full of logic elements.)
Developments in calculator technology very quickly made it possible to use many fewer elements shared between components, which likely contributed to the short life span of these units. Has been hard to pin down an exact serial range or production figures, but it appears to be somewhere in the range of about 1000, production started in 67 but was already being terminated in 68, mine is i believe an early unit, lacking several small cosmetic changes, and is #50620, the highest serial i've found online is 51259.
Comes with full manual and interestingly, the original purchase receipt from 02/69, which would have been after production had ceased and it's successor was either out or close to it. Still, the unit sold for 0 (4,767 adjusted for inflation). These were serious machines for serious business, the fact that the unit still operates flawlessly despite it's thousands of
solder points illustrates that.
A very hard to find calculator that defines a specific moment in the evolution of the technology. I haven't been able to locate another for sale or even a record of a sale, and all of the vintage calculator sites typically rate it's 'rarity/collectability' at the highest level. Unit is in perfect working order, case has a few minor scuffs from the last 50 years, overall in very good condition and seemingly well taken care of, down to the fact that it's still travelling with it's manual original bill of sale.
Item will be shipped exceedingly cautiously, with insurance.
Thanks for looking