Everything worked out well. Just to make sure the old NVRAM was still OK after all the desolder and reading procedures, inserted it into the newly installed socket and the scope booted up normally into the exact same configuration before last powering it off. I also went to Exer02 and confirmed all the changes I saw when I first read the original NVRAM data, and it matched the ones reflected on the chip data. So maybe the vertical balance adjust I did, or something else changed those first and a half lines of the data between 1E00 and 1E10, as I pointed out a few posts back.
Did one last read of the original NVRAM of the scope and programmed the new NVRAM. Scope came up like nothing happened, exactly the same configuration, as seen in one of the attached pictures. Then programmed all FFFF"s into the new NVRAM (not sure that is the correct way to erase all data, as the Erase function on the programmer itself seemed not to work and was giving me an error). Anyway, verified that the new chip was all FFs by reading it, and the proceeded to open the template BIN file with all the data from the EXER02 procedure (updated to reflect those later changes). The scope booted almost normally without any errors but as expected showed a somewhat strange configuration as seen on another picture (I also made a movie of the boot-up process, but its in 1080P so its a 70MB MOV file), and at the end of the boot process there was no trace or readout on the screen. After some fiddling I noticed the trigger was set to Single SEQ, and after changing it back to Auto a really slow and extremely bright sweep came up. Uuups quickly turned down the intensity knob. Also the trace was no where near being centered, neither horizontally or vertically. But after turning all the related knobs either way a bit things started to settle, and the readout also came back on screen. I did not do any extensive tests for accuracy, but from what I saw all seemed to be OK, and since the scope did not complain I'm guessing the cal data checksum was good. Pulled the NVRAM to read it and saved the contents to file so any changes done by the scope to the template data are recorded for future analysis if needed.
Then again wrote all FFs into the fresh 1740 datecode NVRAM and wrote the data from the last read of the original NVRAM and put it into the scope. Upon boot up all seemed fine other that one relay made a bit of a short buzzing sound instead of the usual single click, and the scope came up normally. Then pulled out the NVRAM and read the contents to file as well, again just to document and archive everything, since I noticed that quite a bit of data from 1E00 down had been changed, not sure this would be because the scope was still expecting to see the earlier Exer02 data from the last test after it settled all the front panel settings. So once again pulled out the new NVRAM and wrote FFs, then proceeded to write once again the data from the last read of the original NVRAM, and this time the scope came up normally, no buzzing of the relay (that might have been a fluke?), and it came up to the same configuration that the scope was into when the old NVRAM was still installed. But this time upon reading again the new NVRAM, there where no changes in the cal data from 1E00 and on.
Last but not least, the FRAM. Soldered it onto the converter board, read it and it was all 0000 (zeros), so proceeded to write again the same data from the last read of the original NVRAM, and pushed it into the socket. Result: scope came up normally, no errors, and in the exact same configuration as expected. Powered down the scope and on again a few times over the course of several minutes, same thing no errors, all seems OK. Waited about 15 minutes, power up and again, everything came up the same and without any errors. Now just checked again, must have been like 30 minutes since I last powered the scope, and it is still booting up perfectly.
So not sure which one of the memory modules I will leave in. Maybe leave the old original NVRAM and see how long it will take for it to fail, but then I might loose some data along the way if any operations are performed (other than a full calibration) that might alter the end result, as it happened between the period of about a month where I first took the Exer02 data down, and the last read of the NVRAM once it was desoldered. Again, I only recall doing a vertical balance by pushing up both channel 1 and 2 input selectors, and it would make sense that this change would get written into the NVRAM, although seems obviously non-critical, as I have not done any serious calibration at all.
Or I could just put away the old NVRAM, and start using the new one, and just forget about it (for a while). But the old one would then probably die silently at some point, which at this point is inevitable anyway. So I think the old NVRAM will definitively stay out.
The other option, and which is probably what I will do for now, is to leave the FRAM in order to see how it behaves over a more prolonged period of time, and put away both the old and the new DS1225's. After all the initial idea was that if the FRAM is confirmed to be stable and working fine, it would allow me to dispense with backup battery blues altogether. Maybe at some point I could swap it out with the new NVRAM if I feel like doing some more tests, and of course always keep up with any minor changes that appear in the cal data.
What do you guys think?