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Sharp Compet 30 (CS-30B)

Advertisement for Sharp Compet 30 (CS-30B), circa June, 1967.
Thanks to Mr. Takaharu Yoshida for providing the scan of this advertisement

The Sharp Compet 30 (CS-30B) is an update to original version of this machine, the CS-30A. The CS-30A was introduced in February of 1967 as a reduced cost version of Sharp's first silicon trasistor-based desktop calculator, the Compet 20. The B version of the Compet 30 appears to have been introduced sometime in the Spring of 1967, shortly after the introduction of Sharp's first machine to use Integrated Circuits, the reclusive Compet 31 (CS-31A), which debuted in February of 1967. The CS-30B benefitted from some design changes that made the machine easier to use than the A version, and (in at least the few known surviving examples) leveraged IC technology to simplify the design. The CS-30A used all-transistor circuitry, while it appears that the CS-30B used small-scale integrated circuit technology in its control circuitry. The CS-30B also 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.

With that said, there is some confusion in the community of calculator historians between the Compet 30 CS-30B, and the Compet 31 (CS-31A). The two machines appear to be identical in appearance and features. At this time there is no known example of a Compet 31 in existence to use to compare with the CS-30B. It could be that the CS-30B and the CS-31A are in fact the same machine. Or, perhaps the CS-31A was a first step, using a small number of IC's, with the CS-30B (which clearly has the logic sequencing board filled with ICs) further extending the use of integrated circuits. Until a CS-31A can be found, this mystery will remain.