HP41 problem..

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Sat Mar 8 17:56:00 2003

> Jos,
>
>
> You have a bad Data Storage IC. Depending on which version board
> is in your 41 it may have from 1 to 4 DS ICs but they are custom built

Didn't some HP41s haev 5 RAM (Data Storage) ICs? Each one 16 registers
long (one for the 'status registers', 4 for the 64 user registers?

> ICs made by HP specificly for the HP 41 so you'll never find one. Time

A trick that works when you have a CV with one of the 'extra' DS chips
failed (that's to say one of chips that hold registers after the first
64), is to crack open a single memory module (which are really common!),
then extract the 'PCB' and wire it inside the 41, in place of the bad IC.
Solder the B3 and B4 lines to put it at the right address. Yes, it's a
kludge, but it works. And alas it's not applicable in this case.
 
> to find another 41 for parts. There are plenty of htem out there that
> have broken displays, bad power supply ICs and/or corroded battery
> terminals.

Perhaps I've been lucky, but I don't think I've ever seen a bad PSU chip
in a 41. Bad CPUs I've had, though.

Damaged battery contacts can be kludged over with a bit of care, so
that's not a reason to regard a 41 as a 'parts' machine...

-tony
Received on Sat Mar 08 2003 - 17:56:00 GMT