[time-nuts] Z38XX

Tom Van Baak tvb at LeapSecond.com
Sat Apr 20 16:57:06 EDT 2013


Sorry, I misunderstood what you mean by "Z38XX". I thought that meant the generic class of HP / Agilent / Symmetricom Z38xx (aka Z38* or 585*) GPS receivers, of which there are many.

If you are referring instead to the freeware Windows "Z38XX.exe" program, then that indeed sounds like a horrible bug. Ulrich, can you confirm?

BTW, a similar problem occurred years ago with early versions of the now popular Prologix controller. Old firmware would, for example, save the ++addr value to EEPROM any time the GPIB addr changed. Now if you used only one GPIB device at a time it made sense to preserve the setting in EEPROM; it's a convenient feature, and there was no problem.

But apparently some users had multiple GPIB devices and used the controller to rapidly alternate talking amongst all the devices, thus changing GPIB addresses many times per minute! This "burned out" the Prologix EEPROM. In general EEPROM is intended to preserve settings over power failures or reboots, that is, rare events, not to simply hold state from second to second or hour to hour. Years ago Prologix wisely changed the default and added an explicit savecfg command to save volatile configuration changes to NVRAM, this solving the problem.

So it will be interesting to hear what's really going on with Z38XX.exe and a Z3801A with FROM F2 output. Perhaps HP cleverly avoided updating EEPROM for redundant [re]configuration requests.

/tvb

  ----- Original Message ----- 
  From: paul swed 
  To: Tom Van Baak ; Discussion of precise time and frequency measurement 
  Sent: Saturday, April 20, 2013 12:44 PM
  Subject: Re: [time-nuts] Z38XX


  Tom it would indeed wear out the NVRAM especially the vintage used in the old 3801. I think that was circa 1998?



  On Sat, Apr 20, 2013 at 3:01 PM, Tom Van Baak <tvb at leapsecond.com> wrote:

    > Wouldn't this eventually wear the NVRAM out if Z38XX left running for long enough?

    The static format spec, not the dynamic time code, is written to NVRAM; read once per reboot.

    /tvb



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