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Diehl Combitron or Combitron S Desktop Calculator

Diehl Combitron S
(Note: Unit pictured is missing clear plastic piece that provids serration for tearing off printed paper tape)
Image Courtesy Martin Willemsen

The Combiton was the first all-electronic calculator from famous German mechanical and electromechanical calculator manufacturer Diehl, introduced in late 1966. Diehl's innovation in mechanical calculators carried over to their electronic machines. The Combitron, and the later Combitron-S, were both ahead of their time. The machines utilized a generalized microprogrammed architecture, which was very advanced for the time. The Combitron was not programmable, but the Combitron S provided learn-mode programmability with programs up to 66 steps in length. Both machines utilized a built-in printer for output. The main memory for the calculator consisted of two magnetostrictive delay lines (made by Digital Devices Inc. of Syosset, N.Y.), one that held the microcode that was automatically loaded from a punched metal tape at power-up time, and the other contained working registers of the calculator, and learn-mode stored programs (Combitron S). These machines utilized fully-transistorized logic (with amazingly few transistors due to their microprogrammed design and heavy reliance on the delay lines for data storage). Both machines provided the basic four math functions with automatic square root. Fixed decimal. The Combitron S also had additional memory registers, and capabilities for interfacing to external peripherals such as punched paper tape readers and punches. Examples of either the Combitron or Combitron S are wanted for the museum.