Old Calculator Museum Advertising & Documentation Archive
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 late 1966 as
a reduced cost version of Sharp's first silicon transistor-based
desktop calculator, the Compet 20.
The B version of the Compet 30 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-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,
but 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 CS-30B's using an IC-based memory board, please contact
the museum by clicking the EMail button at the top of the page.