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WP 31S Scientific Calculator


Note: Because the HP 30b has been discontinued, I no longer have "perfect" units available. All 31S calculators that I am shipping now have noticeable keyboard issues, where multiple keys take more force in order to register. Unfortunately there is nothing I can do about this, as this exemplifies the poor quality control of HP's current offerings.

The WP 31S is the "light" version of the 34S, which is most powerful scientific (non-graphing) calculator on the market. It is not an HP product, but it is rather a community-created product based on an existing HP calculator platform. The software of the 34S was written largely by Walter Bonin and Paul Dale, initially just as a PC program. Later, Marcus von Cube joined the team and made it run on the HP 20b/30b platform.

This means I carefully attach the overlay sticker. Finally, I flash the latest version 1.2 ROM (from SVN).

Note: For international deliveries, I can ship it by First Class Mail, reducing the shipping fee to around US$25 (instead of $40+). However, there is no tracking available with this shipping method. Please email me for details.

Physical Characteristics

Technical Specifications

Calculating Environments




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Part of the HP Calculator Archive,
Copyright 1997-2019 Eric Rechlin.