In message 20100608164407.a9783112...@mail.ebirds.it, Marco IK1ODO -2 writes:
Speaking of the 3458A, it has three DS1235Y-150 non volatile SRAM on
the CPU board. Each is a 32K x 8 bit, so there is a lot of info inside.
As the useful life of those is in the order of 10 years and most
3458A a re now 10 to 20 year old, is there a possible replacement?
Possibly with a more modern component?
I replaced all the NVRAM's in mine last month, no issues.
There are plenty of NVRAMs to be had as new.
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
restore.
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.
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
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