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Sharp Compet 32 Model CS-32C Electronic Calculator Advertisement

Advertisement for the Sharp Compet 32 Model CS-32C Calculator
Electronics Magazine, March 3, 1969

An advertisement for the CS-32C version of the Sharp Compet 32 electronic calculator, as well as two lesser stable-mates in Sharp's line of calculators, the Compet 17 and Compet 22.

When the Compet 32 calculator was first introduced in August of 1967, the machine marked Sharp's highest-powered desktop calculator to date. The machine provides a full 16 digits of capacity, has two accumulator-style independent memory registers, and two-key automatic square root, along with the usual four math functions. Along with being the most powerful, it was also the smallest calculator that Sharp had made, using advanced circuitry to shrink the machine down considerably from earlier calculators in Sharp's lineup.

At the time the Compet 32 was introduced, the calculator represented a new design paradigm for Hayakawa Electric (which was the name of the company before it changed its name to Sharp Corporation in January of 1970). Earlier calculators made by the company utilized individual flip flop-based registers, drove the Nixie Tube displays individually using decoder/driver circuitry for each digit in the display, and used a digit-at-a-time calculating method.

The Compet 32 switched to the use of a small magnetic core memory array for storing the registers of the calculator, utilized multiplexed display technology where only one decoder/driver circuit was shared by all of the digits of the display. Multiplexing drives only one digit at a time, with all of the digits each lit for a short amount of time before switching to the next digit. This was done fast enough that the human eye perceives all of the digits of the display lit at once. This method saved a great many components by sharing one decoder driver circuit between all of the digits of the display. Display multiplexing also fit well with the next architectural difference between the Compet 32 and earlier Sharp calculators, which is that calculation is done a single bit at a time versus a digit at a time. This was another component-count reducing change, because rather than having a full four-bit arithmetic unit, the arithmetic unit only operated on one bit at a time. This was a bit slower, but saved a lot of components. Along with these architectural changes, the Compet 32 continued the use of small-scale bipolar integrated circuits that began with the Compet 31, further reducing the component count needed to implement the logic of the calculator. All of these things combined to allow the Compet 32 to be dramatically smaller than Sharp's previous rather bulky calculators, as well as reducing manufacturing complexity, increasing reliability, and in the end, reducing the cost-to-manufacture. Some of the reduced cost to make the machines which was passed on to the consumer, with the rest improving Sharp's margin on sales of the machine.

Especially in the late 1960's, it was not uncommon for calculator companies to keep selling a machine for as long as possible in a hugely competitive marketplace. The development cost of a new calculator design was very expensive, so selling the machine for as long as possible allowed the development cost to be amortized over the lifetime of the product. The longer a given model of calculator was able to be sold into the market at a competitive price and still provide a decent margin on each sale was key to maintaining profitability. For this reason, calculator companies would task their engineers to revisit the design of existing calculators looking for ways to improve the design by making changes that reduce the component count, fix minor issues that have been identified by service statistics as common reliability problems, utilize newer technology where available and effective in reducing manufacturing cost, and implementing changes to the mechanical hardware to make the calculator easier to assemble. The changes were made in such a way that they did not change the look or features of the calculator in any substantive way, but either allowed the calculator to remain price-competitive in the marketplace for a longer period of time, or may have made minor changes to the calculator's operation that were desirable from a user's perspective, such as adding an indicator that lights when a memory register contains any number other than zero(essentially a memory-in-use indicator) or adding support for true negative numbers (versus tens-compliment representation).

In the case of the Sharp Compet 32, like all Sharp calculators, the initial model of the calculator has an A suffix to the model number, e.g., the initial Compet 32 calculator had a model number of CS-32A. The calculator advertised here is the Compet 32 model CS-32C. Usually, revisions to a given model involve moving to the next letter of the alphabet for the model number suffix, but it appears in this case that Sharp jumped from CS-32A to CS-32C without making a CS-32B model. At least as far as is known at this writing, no model CS-32B Compet 32 calculators have been found. If you happen to know of a Sharp Compet 32 Model CS-32B, please click the EMail link above and let the museum curator know about it. The museum does not yet have a Compet 32 Model CS-32A to compare with the Model CS-32C that it currently has (but has not yet had an exhibit created for it at this writing) in the collection, so it is not known specifically what the differences are between the CS-32A and CS-32C, but it is suspected that they involve refinement of the logic design to reduce component count, with associated layout changes to the circuit boards. There may also have been changes to the circuit boards to make the boards easier or less-expensive to manufacture. It is also likely that there were changes to the display drive circuitry, as it is known that the original Compet 32 CS-32A display drivers had some components that were under-rated for the voltages that the displays use, which could have caused failures that were easily unavoidable by replacing these components with parts that had higher voltage ratings. Other changes could have been in the power supply circuitry to simply it as well as potentially improving its design. Until the museum can get a Sharp Compet 32 Model CS-32A for comparison purposes, the exact details will remain unclear. If you have a Sharp Compet 32 Model CS-32A that you would like to find a new home for, please consider contacting the Old Calculator Museum.