Old Calculator Museum Advertising & Documentation Archive
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-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.