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Sharp Compet 30 (CS-30B)

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

The Sharp Compet 30 (CS-30B) is an update to original version of this machine, the 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 CS-30 "B" version was introduced sometime in the Spring of 1967, shortly after the introduction of Sharp's stated first production electronic calculator to use Integrated Circuits, the reclusive Compet 31 (CS-31A), which debuted in February of 1967. The CS-30B was slightly lower priced than the CS-31A.

The CS-30B benefitted from some design changes that made the machine easier to use than the A version. Most importantly, the CS-30B properly handled negative numbers, while the CS-30A would display the tens-compliment of a negative answer. Along with the negative number indication, the 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.

There is some confusion with regard to the CS-30B, as an example of this calculator has been found that uses the small-scale integrated circuit memory register circuit board supposedly introduced in the Compet 31, but is badged as a Compet 30 Model CS-30B and has internal markings indicating that it is a model CS-31A, e.g., a Compet 31.


Sharp Compet 30 Model CS-30B with internal chassis stamping identifying it as a CS-31A, or Compet 31.
Image Courtesy of Mr. Serge Devidts, Calcuseum

This apparent conflict is a mystery that could simply be explained by the fact that the Compet 31 badging was not yet ready for production, but the IC-based memory board was, and so some Compet 30B's were upgraded to use the IC-based memory board, and were marked inside as CS-31A, byt were shipped badged as Compet 30 CS-30B's. This mystery will likely remain a mystery until a Compet 31 can be found and documented, or someone who worked for or sold/serviced Sharp calculators back in the day can shed some light on it. If you have any information about Sharp Compet 30 model CS-30B's using an IC-based memory board, please contact the museum by clicking the EMail button at the top of the page.