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Landscape RPN calculator with alphanumeric display
12-08-2014, 04:00 AM (This post was last modified: 12-15-2014 01:01 AM by Dale Reed.)
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RE: Landscape RPN calculator with alphanumeric display
Yes, a few of us have played around with designs for such a creation, Walter and I and a few others. I've gotten to the point of collecting a number of components, and I have dinked around with some of the parts in a test setup.

The items I'm playing with would make such a unit cost prohibitive to sell. The display I'm using, in single unit quantities, costs me more than many people would pay for such a calculator.

I've gathered together some SO-sized surface mount chips for a LiIon charge controller (and a LiIon cell), a couple different LDO voltage regulators, a MEMS-based real time clock, SD card socket, USB mini-B socket, surface mount tact switches for the keyboard, a 4-line character display, 256k x 8 SPI FRAM, etc., etc. My "dinking" breadboard uses a Freescale MCF51JM128, but I was considering using a Silicon Labs SiM3U-series microncontroller. I have some of both chips. (These are TQFP parts, something I haven't tried hand-soldering yet...) Just haven't gotten around to laying out the PCB for all of this. Something I was hoping to do over the Christmas/etc. holiday season.

I also have a 3D printer and am hoping to print the shell and keyboard buttons for it. (I doubt I can achieve the resolution needed for recessed / double-shot legends on keys, however, even with an 0.25 mm nozzle.)

Anyway, home stuff gets in the way of toys and play time.

Search the forum for "Keyboard Challenge" -- Eddie Shore started such a thread several months ago ( http://www.hpmuseum.org/forum/thread-1243.html ) for designing a calculator with 25 keys (just in time for the 40th anniversary of the HP-25, perhaps). There are older topics with some 39- and 43-key landscape machines that Walter and I proposed, as well. I would like to see one with the double-wide ENTER^ key horizonally in the center of the bottom row of keys (to double as a space-bar for typing, perhaps) and my couple of designs reflect that.

Can't find the picture of the 43-key beast on this PC, but I will edit this post later and attach it.

Edit: Here's one that I came up with (it has since been changed to swap the display to the left and the arrow keys to the right):

   

Edit: Also, I hope Walter doesn't object -- I also attached a picture of one of his landscape designs (Walter, if you want me to remove this, just let me know.) :

   

Dale
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RE: Landscape RPN calculator with alphanumeric display - Dale Reed - 12-08-2014 04:00 AM



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