>I have to disagree with Marc about some of his post. We've seen
>where a failing/failed PRAM battery has caused failure to boot, to
>raster properly, to network properly and a variety of other issues.
>it's not just a clock issue. On some models, having the battery out
>causes significant issues -- on others it does not appear to be part
>of critical circuitry.
Absolutely - I didn't mean to imply that booting with the PRAM
battery disconnected would work on any Mac. I have verified that it
works on my 2400 - YMMV. I've also used a couple of older Powerbooks
(including a Duo) that way when no battery was available, relying on
a control panel to restore some saved PRAM settings after boot time
and an NTP client to set the clock from a network server.
Many older Macs, especially NuBus desktop models, can't boot at all
without a good battery - they go black and stay that way until the
battery is replaced (this was probably historically convenient for
Apple dealers, since a customer would take back their "dead" computer
for a $50 repair they could easily have done themself). You can still
temporarily disconnect the battery to completely zap the PRAM on
those models, but it's generally not necessary since they have no
Power Manager nor the associated problems (as Paul mentions, the PRAM
can already be cleared through a firmware call by Techtool et al).
The gist of my suggestion to Ilene is that a failing battery is
frequently worse than an absent one (in those Macs that can run with
it absent), and if the PRAM battery is suspected, disconnecting it
for a while can be a useful diagnostic tool. I have certainly come
across Macs that couldn't boot with a near-dead battery, but could
with no battery at all.
>He is absolutely correct in that if you want to reset your power
>manager and low-level PRAM settings, disconnecting everything for a
>while is certainly a way to do that. We've also found that using a
>tool like TechTool can do nearly as good a job in resetting the PRAM,
>without the hassle or danger inherent in opening up the laptop (see
>our micromat listing at
>http://www.afterhoursconsulting.org/links.html for the url).
Techtool does do a good job, though it's never been quite clear
whether zapping the entire PRAM is enough to clear out the Power
Manager. This is testable: you'd be able to tell if a shutdown after
zapping caused the steady green light to glow (ie. zap the PRAM, then
turn off the computer with the hard power switch before it can
reboot). I suspect it probably isn't - there appears to be some
additional battery-backed CMOS memory on the power management chip in
Powerbooks.
--
Marc Sira | [EMAIL PROTECTED]
"If you can't play with words, what good are they?"
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