[rescue] Hanging with NVRAM in?

[Jan-Benedict Glaw]

On Thu, 2025-11-20 08:43:00 -0500, Mouse via rescue <rescue at sunhelp.org> wrote:
> With the NVRAM socket empty, the boards power up and go through
> selftest just fine - well, as fine as can be expected; they complain
> about the NVRAM not retaining data, but that's no surprise when there
> isn't any NVRAM there.  They even boot diskfully, albeit with a
> 00:00:00:00:00:00 MAC.
> 
> But with the NVRAM in the socket?  They don't print any of the selftest
> messages on power-up, not even the first few that they print even with
> no RAM installed.  (I didn't wait long - several seconds - but the
> first messages are normally close enough to instant that at the human
> layer I can't see any delay.)
> 
> So I tried the other boards, the ones that worked (with the same
> MK48T02B) before.  Same syndrome.
> 
> But pull the chip, and they go back to "working".
> 
> Anyone have any idea what might be behind this?

On VAXstation m90, I've seen that these play dead with a dead RTC chip
as well. They're actually using the NVRAM right after power-on. I've
never tested them w/o a RTC chip, though, but I guess they won't boot
just like with a dead battery inside the chip. Seems battery power is
actually required for the NVRAM part to work, not even external power
is enough.

MfG, JBG

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