Letter to the editor, Wireless World 1972-09 p.19

Sinclair pocket calculator

I was very disappointed by the mention of our calculator in the News pages of your August issue. It seems to me that this was an entirely negative piece of reporting which did nothing but criticize inaccurately what we feel to be a considerable technical achievement.

As you may be aware, a great number of companies have announced that they are making pocket electronic calculators in this country but to the best of our knowledge we are the only people actually doing so. Furthermore, our calculator has been the most enormous immediate success both in England and abroad. Far from being behind our competition we are very far ahead of it. Several very large companies abroad have asked for licences for our design and circuitry, these are the people who have seen and used our machine.

The criticisms made by your correspondent are so ephemeral and at times meaningless that they are hard to deal with individually, nevertheless I will try. The switch contacts which he describes as being rather crude are plated beryllium copper and if anyone knows a better way to make a switch than the one we are employing we would be delighted to hear about it. The keyboard on virtually all competing machines can, if hit fast enough, fail to make an entry; this is not the case with our machines for reasons which are clearly rather too subtle to have been obvious to your writer. I cannot understand how he found fixed /floating point selector switch difficult to use, he is certainly the only one to complain about it. The on /off switch is definitely stiff and it is intended to be. This prevents it from being accidentally switched on when the machine is slipped into a pocket.

The reference to Texas Instruments not guaranteeing the chip in our circuit is really rather irrelevant. We have never asked Texas Instruments to do so any more than we ask them to guarantee the operations of their transistors in our other circuits. As a matter of interest, however, Texas Instruments have complimented us on the ingenuity of our application and have stated that they see no objection to it whatsoever. Your correspondent also says that we ought to do a temperature cycling test on every machine. We have done a great many tests on individual samples but to do this test on every single machine would be uneconomical and totally unnecessary. We have left our machines immersed for several days in water and they work perfectly well afterwards but we do not propose to carry out this test on every machine just in case somebody drops theirs in the bath.
C. M. Sinclair,
Sinclair Radionics,
St. Ives, Hunts.

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First published Wednesday the 7th of September, 2016
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