HP12C battery problem solved and studying RPL

[DaveBr]

Quite a while ago, I found a HP12C on top of a garbage can with a sticky note on it that indicated it was broken. I put the 12C in my pocket and when I got home, I tossed it in a drawer, intending to see if I could get into work as a spare in case my wife's 20+ yr old 12C croaked.
Fast forward 5 years or so to this morning. I was looking for something in a drawer and found the salvaged HP12C (the sticky note was still on it). I pressed the ON button and the calculator showed 0.00 in the display. A couple of key presses later, I thought all was well. When I set the calculator down on the counter, the display faded out and the calculator wouldn't turn on - until I picked it up. It worked fine in my hand. Time for disassembly.
When I opened the calculator (easy), I found the 3032 battery holder contacts were bent, making compression contact and there was a lump of plastic under the battery. The plastic lump was one of the many heat-staked posts holding the internals together that had broken off and gotten under the battery.
I was really disappointed at the design of the battery holder. I've seen better in $5 children toys. My wife's older 12C uses three 357 batteries and is rock solid. This newer one - not so much.
BTW- The newer 12C now works fine.
Dave

[Thomas Klemm]

Congratulations.

Now it's time to do something useful with it like testing the Collatz conjecture with 27 using the (12C) 3n + 1 conjecture program from the Software Library.

Cheers
Thomas

PS: Don't keep your calculators in the drawers.

[DaveBr]

(07-06-2018 07:12 PM)Thomas Klemm Wrote:  Congratulations.

Now it's time to do something useful with it like testing the Collatz conjecture with 27 using the (12C) 3n + 1 conjecture program from the Software Library.

Cheers
Thomas

PS: Don't keep your calculators in the drawers.

That looks interesting. You guys are way smarter than I am.

Today, I have been perusing RPL in my 48SX manual. I haven't written a RPL program in years and years. I've been thinking about writing a program that simulates a (very) simple Turing machine using the calculator display matrix rather than a tape.
Here is the pseudo code in my noggin:

repeat until any key
goto a random (x,y) location in the display
test if the pixel (x,y) is set or clear
if set, clear (x,y) and move left
else, set and move right
end

Simple program (I think). It would be interesting to add more rules and see what happens.

BTW, I keep most of my calculators in a cabinet. My 41CX and 48SX are nearby.
Dave

[Thomas Klemm]

(07-06-2018 10:16 PM)DaveBr Wrote:  I've been thinking about writing a program that simulates a (very) simple Turing machine using the calculator display matrix rather than a tape.

And then once you're finished you run the Collatz conjecture program on it?

Quote:You guys are way smarter than I am.

I beg to differ.

Honestly, that sounds like an interesting project.
Please post your results.

Kind regards
Thomas

[revwillie]

(07-06-2018 04:30 PM)DaveBr Wrote:  I was really disappointed at the design of the battery holder.
Dave

I just got a newer 12c for about 10USD off ebay. It was sold as "needs new battery". But in trying a new battery, fiddling with the contacts, and disassembly, I found that one of the battery compartment screws was rolling around inside the case. The battery holder fingers had to be gently bent out towards the PCB to attain reliable contact with the PCB, but now I have a totally working 12c. ...and the battery that came with it is fine.