HP 20b biz calc can be modded

Make Pt0926
A few makers sent this in… the latest HP 20b biz calc can be modded’ (they’re releasing a dev kit). I downloaded the dev kit, they’re not messing around, schematic is included. Gang, this is an Atmel ARM, an LCD with the power supply done – what the heck is going on here? Way over powered for a calc, just asking for projects – Makers please do something cool with this!

22 thoughts on “HP 20b biz calc can be modded

  1. Not only HP’s mojo but their cred and it’s overdue.

    Reading through the documents, one gets the sense that a tinkerer is at the helm of this idea. Backtracking the name and Email address listed in the documentation outs the head of R & D for Hewlett-Packard, Cyrille de Brebisson as the hero behind getting this out of the corporate murk:


    Wouldn’t it be great if every widget maker were this amenable to messing around with their products?

  2. HP may have made a snazzy bit of kit here, but it’s not RPN! Oh, wait, how about a mod that turns the “=” key into “Enter” and makes it calculate the way that a proper HP would do! With the stack, and the postfix notation…

  3. Since the interesting links are missing in the article:

    Developer Kit download: http://h20000.www2.hp.com/bizsupport/TechSupport/SoftwareIndex.jsp?lang=en&cc=us&prodNameId=3732535&prodTypeId=215348&prodSeriesId=3732534&swLang=13&taskId=135&swEnvOID=54

    Wiki for the HP 20b repurposing project: http://hpwiki.fatcity.com/doku.php?id=20b:repurposing_project

    And – to complain – of course the Calculator has a pricing point of 55 EUR in Europe. Which currently is twice the price as in the US :-(

    Have fun,

  4. I take it all back — the HP 20B has an RPN mode, described by HP as “time-saving RPN”. Yes, HP is back in the calculator business. Now, I wonder if the PCB is gold-plated all over, like they used to be? And I wonder if it can work in hex?

  5. It’d be a lot cooler if it were a “landscape” form-factor, like the old HP 12c and its ilk (like the mid-1980s HP 15c I had back in the day.

  6. I’m catching the link to HP’s product page but I’m missing the link to modification info. Any help? Training wheels?

    Also let me second anachrocomputer’s comment. I just got a new HP-35s. HP calculators are back. I’d love to know if the same mods will be practical for the 20B’s similar-looking bigger cousin.

  7. I can’t help but wish that it were starting out as a scientific calculator– I’m not sure that I’d want to be seen with a business calc! :P

    But… 30 MHz AT91SAM7 and 9 months battery life on two CR2032s… wow. My old HP48SX graphing calculator– no slouch at the time– had a 2 MHz 4-bit CPU. This thing is a monster!

    Now, the *real* test of whether it’s mod-able is the construction. Many classic HP calcs were molded shut and could only be destructively opened. Anyone know?

  8. To answer the last posters question:

    The user manual for the device talks about opening the calculator case. There’s also a programming (JTAG) header in the schematic, and the developer kit has all the source code for the ROM.

    Looks like your covered. =)

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