I was able to select a DS1230Y NVRAM package on the TNM5000 and read U500. However, it only contained 32 bytes of data. Everything else was alternating 32 bytes of 00 and FF.
I should note that when I selected the NVRAM part, the TNM put up a warning to select the device before inserting the device in the ZIF which is the opposite of what I did.
Does anyone have images of U500 and U511 from a CSA803 or 11801 which has the factory cal data? We'd also need the 200 MHz OXCO measured using a GPSDO referenced counter and the version of the timebase board ROMS. Mine are version 10.1 dated 1991.
Does anyone of the list know who designed the board? It's dated 1988. It they are still alive we might get some help from them.
Is there any information on the recalibration process?
This needs to be documented before all of them fail. Twenty odd years ago there was a detailed description of how to recover a Sun workstation from a failed NVRAM. So if you bought a used system, one of the first things you did was record the serial number, etc for future reference.