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Old Calculator Museum Advertising & Documentation Archive
Sharp Compet 30 (CS-30B)

Advertisement for Sharp Compet 30 Model CS-30B
Electronics Magazine, July, 1967

The Sharp Compet 30 (CS-30B) is an update to original version of this calculator, Sharp's Compet 30 Model CS-30A. The CS-30A was introduced in late 1966 as a reduced cost version of Sharp's first silicon trasistor-based desktop calculator, the Compet 20. The B version of the Compet 30 was introduced in March of 1967, shortly after the introduction of Sharp's first production electronic calculator to use Integrated Circuits, the reclusive Compet 31 (CS-31A), which debuted in Japan in February of 1967. The Compet 31 was not exported outside of Japan due to concerns over patent issues with Texas Instruments (TI) in the US. TI held patents on the invention of the integrated circuit, and was threatening to blockade any Japanese electronics containing integrated cicuits until it was allowed to start up a jointly-owned venture in Japan to produce integrated circuits. This conflict resulted in delays of IC-based calcualtors from Japan showing up on US retail shelves. The Compet 31 was identical in function the Compet 30 model CS-30B other than the memory register of the Compet 31 was implemented using Mitsubishi-made TTL ICs versus the discrete transistor memory register implementation of the CS-30B.

The CS-30B included some improvements that made the calculator easier to use than the original Compet 30 CS-30A version. CS-30B added two indicators at the left end of the display; an error indicator that lit red when an overflow occurred, and another indicator that lit yellow to indicate that the memory register contained non-zero content. These small changes provided better operator visibility of overflow conditions, reducing the chance for error when an overflow occurred. The memory status indicator helped the operator keep tabs on the status of the memory regiser, also helping to reduce errors related to use of the memory register.