Mark, I am using the STMicroelectronics M48Z12 series in at least one of my 3458A's. I had trouble sourcing one of the two different memory modules from a reputable seller when I replaced my NVRAM. I purchased a DS1220 previously from Jameco and it died shortly afterward. The datecode on the Jameco part was several months old and may have been stored improperly.
The only thing I don't like about the STMicro NVRAM is that they use a three digit datecode. One digit is for the year and two for the week. It took me a while to track down a document to decipher their labeling system. Todd On Thu, Aug 7, 2014 at 12:20 AM, Mark Sims <[email protected]> wrote: > I have three HP3458A's and decided it was time to back up the battery > backed static RAM chips. I wrote a program to dump the RAM contents over > the GPIB bus using the undocumented MREAD command as documented by > Poul-Henning. I dumped both the 2kB CAL rams and the 32kW auxiliary data > RAMs (hopefully that data is at the addresses mentioned by Poul-Henning. > I used a NI GPIB-232CV-A RS232 to GPIB converter as the interface. All > seems to have gone well and the CAL data looks reasonable. > As a check I dumped all the data from each machine three times and > compared each dump... each CAL data set matched except for the third > machine. On the first two, the units were powered on for a couple of > hours while I tweaked with my code. I dumped the third machine from a cold > start and one byte was different between each dump. I waited a couple of > hours and tried again, this time the data dumps matched. It looks like > that byte may be being updated while the machine warms up... If you dump > your machine's data, it might be a good idea to let it stabilize for a > couple of hours first. > The dumps of the 32kW of aux data have several words that change between > each dump. It looks like that memory has some uses by the firmware other > than storing user data, etc. > I think when the time comes to replace the battery backed memory chips I > may try Cypress/Ramtron FRAM chips or Simtek STK16C88 AutoStore devices. > The Simtek chips are available in 28 pin DIP packages that appear to be > drop-in replacements for the DS1230 chips. The DS1220 chip would require a > SO8 packaged part on a carrier board. > _______________________________________________ > volt-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts > and follow the instructions there. > _______________________________________________ volt-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
