[time-nuts] pm - re: Dallas NV-SRAM replacement? (in 3458A)

Marco IK1ODO ik1odo at spin-it.com
Tue Jun 8 18:47:53 UTC 2010

Hello Poul-Henning,

>I replaced all the NVRAM's in mine last month, no issues.
>There are plenty of NVRAMs to be had as new.

that's good news. What have you used?

> >Also, of course it would be a good idea to read and save the contents
> >of the SRAMs before replacing, but... is any custom data in them that
> >cannot be rewritten with a complete recalibration?
>The CALRAM contains a number of "magic" counters, one of which is
>called "destructive overloads" that a calibration cannot possibly
>But from a functional point of view: no.
>You can read out the memory with the undocumented "MREAD" command,
>but the CALRAM is protected by various tricks, so you cannot just
>use the MWRITE command to restore it.

So, have you read the RAM with an eprom-programmer, and then rewrote 
them, or simply replaced?


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