26 Sep
2011
26 Sep
'11
11:22 a.m.
AFAIK nobody
other than
HP makes
reverse-polish caclualtors.
Do you have a 41C*? If it's a CV, you're in luck. There's an article
in a recent issue of Circuit Cellar that describes the
resurrection of
one via programmable logic. That's the second article they've run (to my
knowledge) that delves into saving old h/w from the scrap heap. The
I am suprised it needs a 41CV (only). The older constuction -- the
'Fullnuts' -- have most of the electornics on a little PCB inside, which
is conencted the keyboard PCB (which is just switches and conenctor
pads). The display modules is connected to the top edge of the keyboard
PCB. There's a flexible PCB wrapped round a plastic block to from the
battery contacts and plug-in module connectors, it also connects ot the
keyboard PCB.
AFAIK, apart from a different overlays, the only differences betwene
th 3 type (C, CV, CX) is the logic PCB. ALl other parts are the asme.
The later construction -- the halfnut, has one PCB withich carries the
keyboard contacts, the CPU chip and a hybrid module contianing the ROM,
RAM, and LCD driver. The CX verison has a daughterboard containing the
extra ROM, RAM and the real time clock (as an aside, note that adding
this daughterboard ot a CV does not turn it into a CX, the main ROM in
the display hybrid is different too)
Anyway, I can fully understand why a hardware rebuild might only work in
a Fullnut machine, but I can't understand why it woudl only work in a CV.
earlier one uses GALs to replace the video chip in an
ELF. The latter
uses FPGAs I think.
I'm not saying the author can or will supply the necessary code. But
it's been done at least we know.
This sounds like the 41CL project, nad AFAIK the designer makes mobney
from it and won't release the sources. Oh well..
Anyway, it doesnt' totally solve the problem. The most common problems on
the 41 series are basically mechancial (cracked plastic posts that hold
the case togethter, damaged flexiprint from battery leakage, etc), and
can often be fixed. But not all electronci problems are on the logic
PCB. I've had the LCD display 'glass' fail (leakage of the LCD material
iteslf), the display driver ICs which are chip-on-board on a little PCB
o the back of the glass could fail too and are not repalced if you swap
the logic board fro some FPGA-based replacement.
And ofc ocurse there are all the plug-in accessories. While the 41CL
contains all the ROM/RAM modules, there are also peripherals like a
printer, magnetic card reader, barcode wand, HPIL itnerface, etc which
can fail, and which are not part of the main logic board.
So while this project is a Good Thing in keepign 41s alive, it's not the
whole answer by any means...
-tony