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Please note that due to serious flooding in my hometown of Houston, I am a bit behind on fulfilling orders. Thank you for your patience as we recover. Also, due to issues with making overlays, no WP-34 or WP-31 related items will ship before mid to late October.

WP 31S Scientific Calculator

Back ordered until Oct 31.

Note: Because the HP 30b has been discontinued, I no longer have "perfect" units available. All 31S calculators that I am shipping now have a minor keyboard issue, where one or two of the keys takes more force to press than the others. If you are really picky it may be an issue, otherwise it is no worse than the other, less-than-perfect modern HP calculators, 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 1997-2015 Eric Rechlin.