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Uchida Yoko USAC 10B Desktop Calculator

Uchida Yoko USAC 10B (Model UC-10B1)
Image Courtesy of Mr. Takaharu Yoshida

The USAC 10B is the first of a series of four different desktop electronic calculators developed and marketed by Uchida Denshi Kogyo Co., Ltd. (later Uchida Yoko Co., Ltd.). Uchida Yoko was (and still is) a large Japanese multi-faceted manufacturing and marketing company involved in numerous businesses, including billing machines and small office small computers, office furniture, scientific equipment for educational institutions, mechanical adding machines, office supplies, and, for a short time, electronic calculators. Uchida Yoko left the electronic calculator market in the spring of 1969 due to intense market competition that made it impractical for the company to remain competitive.

The USAC 10B calculator was the company's first entry into the electronic calculator market, and was introduced in June of 1967. The USAC-10B was advertised as the world's first production all-IC desktop electronic calculator, a claim which is incorrect, as the Victor 3900 lays claim to this distinction, introduced nearly a full two years earlier. The USAC 10B is of a very unusual design, perhaps being the only production desktop electronic calculator to exclusively use RTL (Resistor-Transistor Logic) Integrated Circuits. The ICs in the USAC 10B are made by the famous American semiconductor manufacturer Fairchild. The machine's logic is built entirely from Fairchild's MicroLogic devices -- approximately 350 of the them. Each MicroLogic IC (10-pin radial lead round plastic packages) contains a few logic gates or a single flip-flop device. The Fairchild MicroLogic family of ICs were the first commercial family of general purpose digital integrated circuits, making the USAC 10B a unique machine from a technology perspective.

The 10B is a basic four-function office calculator, with a single accumulator-style memory register. Capacity is 10 digits, with a Nixie tube display. It operates with keyboard pushbutton-selectable fixed decimal position. Follow-on calculators included the USAC 10R (added square root), the USAC 22B, and the USAC 22R. The Old Calculator Museum would like to acquire any of these models. If you have any information, documentation, or photos of any of Uchida Yoko's calculators, please contact the museum by clicking on the EMail button in the menubar at the top of this page.

Uchida Yoko USAC 10B Specifications

Manufacturer: Uchida Denshi Kogyo Co., Ltd. (Uchida Yoko)
Model Number: UC-10B1 (USAC 10B)
Manufactured In: Japan
Date of Introduction: June, 1967
Display Technology: Nixie Tube, 10 Digits
Logic Technology: ~350 Fairchild MicroLogic small-scale RTL ICs
Digits of Capacity: 10
Decimal Modes: Fixed via pushbutton at 0, 3 and 5 digits behind decimal
Math Functions: Four Function
Memories: One accumulator-style memory register
Constant: Yes. Unclear if available for addition/subtraction
Features: Backspace key for error correction
Performance: Addition/Subtraction: 1ms; Multiplication/Division: 20ms
Size: 13" wide, 16" deep, 8" high
Weight: 20 pounds
Power Requirements: 100V (Japanese Market), 90W, 50/60Hz

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