Canon Card F-55S scientific calculator from 1979: The most compact of all?

[jebem]

The Canon Card F-55S scientific statistical calculator is probably the most compact and smallest machine from their time (1979).

I got this one from a local auction site. It shows some wear but it works flawlessly.

To complete the set, I found the ultra compact user guide for sell in Spain in very good shape, so I've ordered it as well.
It is a 115 mini pages (111 x 70 mm) and contains instructions in four languages (English, German, French, Spanish and Italian).
Reference from the back cover: PUB.IM03-079D, 0580B10 PRINTED IN JAPAN.

Edit:
Available for download from Katie Wasserman site here.


This machine sports a full metal body on the outside, covering the inner plastic frame.
It uses a clever 4 by 4 function selector mechanism (used by other calculators of the same era) to reduce the number of keys in the keyboard, thus allowing to decrease the case size.

Based on a Toshiba T3934S SoC (partially visible in one of the photos), it consumes a nominal power of just 500uW (167uA) from a CR-2016 3V button cell.








For physical sizing comparison, here it is side by side with the HP-15C.