[volt-nuts] HP 3458A Mem test 1 hight. How do you read 32K memory chips?

[Mark Sims]

You REALLY don't want to mess with that 24 pin NVRAM chip... it contains the calibration memory.  If you bugger the data in it,  you get to spend a couple of grand getting the meter back into working order.  I know a couple of people that did just that.

The solution is to first make a backup copy of the memory contents using the (undocumented) MREAD command over the GPIB bus.  Poul-Henning Kamp figured out how to do it... buy the man a beer... even better a case of beer...   Search the archives for details.  

I just backed up all the memory in my 3 HP3458A's for when the inevitable BIG BAD DAY comes and the backup batteries go bye-bye.   If you happen to have a NI GPIB-232CV-A (or possibly a Prologix) RS-232 to GPIB converter and can run a DOS or WIN98 program,  I have a program that dumps the memory chips.  It has code for the Prologix in it,  but I've only used it with my a Prologix compatible unit I built... I don't have a real Prologix to test it with.