[time-nuts] HP3458A calibration memory backup

[Mark Sims]

I did some more playing around with the 3458A memory dumper this weekend.   I built up another system using a different computer/cables/software/GPIB interface (one I built using an AVR chip that emulates the Prologix RS-232/USB converter).   I noticed than  a couple of dumps of the CAL ram (out of maybe two dozen runs) had one byte near the end of the RAM (in that same string of 01 bytes) sometimes read as 00 or 05.  This was with a different 3458A and it has been continuously powered for a couple of days.  Perhaps the memory chip is not enabled at those addresses and it is reading a floating bus?