Subject: Re: SparcStation ipx versus Sparc Classic
To: None <port-sparc@netbsd.org>
From: der Mouse <mouse@Rodents.Montreal.QC.CA>
List: port-sparc
Date: 05/02/2002 13:30:46
> Turning off the oscillator hardly seems worthwhile -- unless you have
> an excess of spare time available  :>  I believe the devices are
> guaranteed to operate for 10 years IN THE ABSENCE OF POWER.

Sure.  But that's no reason to push it.  The 10-year lifetime is
running out on many of them, and every drain the battery doesn't have
is that much more life that it has before it needs attention.

> Even with the oscillator disabled, the BBSRAM still draws power

It does?  Maintaining static RAM contents requires approximately no
power, just voltage - CMOS devices draw extremely low currents when no
switching is taking place, current in the nanoamp range as I recall,
on the order of the leakage current through the insulators that make up
the chip packaging. :-)

> and the "battery" still has self-discharge characteristics.

Certainly.  The chip datasheets claim that that is the major discharge
mode with the clock stopped, but not with the clock running; I find
these claims plausible.

> Personally, I find it annoying to have to remember to reset the clock
> if I take a machine out of storage...

I don't have a problem with that, as I always have ntpdate and ntpd
turned on. :-)

> and, the battery is *still* going to fail at *some* point  (i.e. just
> attach a whopping BIG battery to the device and forget about it...)

Sure; if I had several hundred 3V battery packs to spare I might feel
the same. :-)  (Were you the person who got tons of them for
approximately free?  I don't recall.)

> I have found that chosing MAC addresses of the form  x:x:x:a:x:!a (et
> al.) makes it easier to program the BBSRAM -- since the checksum
> doesn't change from one machine to the next (one less byte that has
> to be computed!)

mkpl recomputes the checksum for you...or at least it does for me.  (I
also think you probably mean ~a rather than !a, to be nitpicky.)

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