was made at the Portsmouth factory (though examples were also made in Mexico—see
and is a basic four function model with an added percent and memory.
Note that, compared to the 8R or
18F, the equals
key is moved to a more 'modern' position. I believe that the 21R is
a 20R with rechargeable batteries and charger included (an accessory
kit was available as a model 01R---in the U.S. at least). The markings
are also different, with the memory M+, M- etc. missing from the 20R.
The image on the left is of a contemporary advert from a U.S. magazine, showing the
21R and other models, from around 1976. Click on the image to enlarge.
This example has its I.C. labelled 7528 (1975 week 28).
The manual for the 21R is available on the
Try it out---it works!
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Last updated 24th April 2006.
© 2003-2006 Simon Southwell. All rights reserved.