Monroe 990 Nixie Tube Calculator w/Magnetostrictive Delay Line Memory

Description: Monroe 990 Nixie Tube Calculator w/Magnetostrictive Acoustic Delay Line Memory YT video link:https://youtu.be/1dcozswgU10 Very good cosmetic condition. Good working condition except: - memory registers have random numbers in them when calculator is turned on; can be emptied by pressing corresponding keys- decimal point dial seems to have inner oxidation of its contacts (similar to crackling sound of older volume pots) and need to be switched a couple of times to make good contact and not to interfere the result display (see video). Bottom rubber feet are deteriorated due to the machine's age (50+ years), can be easily replaced as are retained by screws. It is a good example of what would be considered a high-end office calculator of its time, which would be in the mid-1960's timeframe.The 990 is visually very similar to its somewhat less feature-laden stable-mate, the Monroe 950. The 990 is identical (other than cabinet and keyboard coloring) to the Canon 163. Given that Canon designed and manufactured the 990 for Monroe, there's no surprise that Canon would have a similar model marketed under the their own name. The 990 is a 16-digit Nixie tube-display calculator. The machine performs the basic four math functions along with square root. It also has two memory registers, one that can serve as an accumulator, automatically accumulating results of calculations, and a second memory register that can serve as an item counter, sum of products accumulator, or a general purpose memory register with addition/subtraction function keys. The 990 is a fixed-decimal point machine, with a large rotary wheel at the right side of the keyboard with settings of 0, 2, 4, 6, 8, or 10 digits behind the decimal point. The display shares the comma indicators of the Monroe 950 that help make answers more readable by grouping digits in groups of three. The display consists of 16 Nixie tubes, each with a decimal point position to the right of the digit. There are also 16 discrete neon bulbs located above and between the Nixie digits, used for the comma indicators. There are also two discrete neon bulbs that indicate overflow and negative conditions, as well as two more that light if the content of either of the memory registers is non-zero. The Nixie tubes are driven by discrete transistor/transformer driver circuitry, and run from a 220 Volt DC supply. The back-most circuit board in the machine is a controller for an magnetostrictive acoustic delay line that is used to store the working registers of the machine. The 990 uses a completely different delay line than the 950, and another similar machine, the Canon 141. The delay line in the 990 is significantly thicker than the delay line module used in the 950, likely because more bits of storage are required for the additional memory registers and functions of the 990 versus the less complex 950. The delay line, as with the one used in the 950, is made by NEC This calculator uses Magnetostrictive Delay Line Memory to store the data.https://en.wikipedia.org/wiki/Delay-line_memory#Magnetostrictive_delay_lines Description of this beauty on the Net:https://www.oldcalculatormuseum.com/monroe990.html

Price: 800 USD

Location: Brooklyn, New York

End Time: 2025-01-29T05:10:01.000Z

Shipping Cost: 0 USD