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Flakey HP 70: post modified as RAM Chip identified.
11-08-2015, 01:48 AM (This post was last modified: 11-08-2015 01:50 AM by Geoff Quickfall.)
Post: #7
Damn it!!!
Well, I picked up a functioning HP 16C and an untested (eBay read for dead) HP 45 in a package for an excellent price. The HP 16C will be a Christmas present for my nephew (programmer).

The 45 WAS to be a donor for an:

1820-0993 RAM chip.

Well wouldn't you know it!!! I got it working after a good PCA and connection clean.

So I took my oldest, rattiest looking 45 PCA and harvested the chip. I now have a functional 45 board that needs a chip, but at least I could insert the chip into the 70 PCA.

And guess what, I now have a fully functional 70 working! It even does Canadian Mortgages, of course that will all change with the new Prime Minister.

So, referring to the faults in the first post, the ROM at power on does insert 12 into the "K" memory which resides in the 1820-0993 chip. The fact the 12 and all other 'memory' function other then the stack pointed to the defunct 0993 chip.

A big thanks AGAIN to Eric Smith and his resource at brouhaha!

best regards all, Geoff
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Messages In This Thread
RE: Flakey HP 70 - Geoff Quickfall - 10-22-2015, 06:22 AM
RE: Flakey HP 70 - Didier Lachieze - 10-22-2015, 06:42 AM
Damn it!!! - Geoff Quickfall - 11-08-2015 01:48 AM



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