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CMT71-64E HP-71b eprom module questions
04-28-2021, 04:42 PM
Post: #25
RE: CMT71-64E HP-71b eprom module questions
(04-28-2021 03:14 PM)Dave Frederickson Wrote:  
(04-28-2021 03:05 PM)dmh Wrote:  Found this in the manual and tried it but it doesn't give 00000.

Programs I've tested seem to work though. Maybe the 32k test in a 64k EPROM is related (unless PTTEST$ is module independent)?

I will keep tinkering - thanks all for your helpful information and tips :-)
As KimH mentioned, PTTEST$ and ROMTST will only pass if a checksum is stored in the EPROM, so if the test fails it doesn't necessarily mean the EPROM is bad.

Further, many (most?) 3rd-party EPROMs did not bother to use checksums, probably stopping once the process of creating them was understood and stable. These are not needed or used by the 71 itself, so only useful to verify manually later on.

Most likely the contents are intact, I've only seen one bad EPROM among probably several hundred (not all mine, but as reported here).

It's pretty clear the original surveying app was wiped and a prior owner simply copied a bunch of 'handy' files onto the EPROM, so they were ready to copy to RAM after a MEM LOST. Some of these files (LEX, BASIC) could be used directly from EPROM, but RPN (a BIN file) cannot, as it stores the XYZT stack values inside itself (presuming that it's in RAM) and does not work at all when run in EPROM.

What are the dates of the various files (the CAT listing is not complete) that would likely give a good hint on when this image was created? Also, what is the size of the COORD and SUBPROGS programs? Back in the day these modules were expensive (actually, still true today, but less so in relative dollars) so it's unlikely the original publishers would have used a 64K module, if the actual application fit on a 32K module. Finally, at least some of these files were commercial and not (legally) allowed to be distributed on a commercial product).

--Bob Prosperi
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RE: CMT71-64E HP-71b eprom module questions - rprosperi - 04-28-2021 04:42 PM

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