From: Jim Witte (jswitte_at_bloomington.in.us)
Date: Wed Jan 07 2004 - 00:54:30 PST
To Knowledge-Masters of Newton Electrical Systems (wait, are there any?
;-)),
I've got a rather odd problem that showed up tonight. The alkalines
I was using in the battery tray failed (never trust a Rayovac..), so I
hooked it up to the AC. The switch doesn't do *anything*. Pushing the
reset button will cause a small little "changing" whine (not the
backlight whine, the other one - I assume the transformer circuitry
responding to varying power demands as the processor goes through the
boot-up sequence. The "tone sequence" is always the same, always
lasting 5 seconds, even if I hold in the reset button. If I hold the
power button while this sequence is going, the whine will go on
constantly, but the screen won't come up.
Then all of a sudden, I noticed that the Newt had booted, saying it
had "restarted due to power interruption. If I turn it off, pull the
plug for 5 seconds, then plug it back in and turn it on, the same whine
sequence is heard, and then it boots again normally.
Could this be because the supercap is dying/almost-dead, and it takes
some time after the power had been applied to charge it enough to turn
on the processor? Does anyone know how the boot-sequence works
electrically? Will the reset-switch/power-switch transistor(s) draw
power from the battery/AC-transformer if it is present, or only from
the supercap, letting another section of the system recharge the cap as
needed?
I've also noticed (I'm sure others have too) that the Newton is often
quite finicky about turning on from a cold boot - sometimes it starts
right up, sometimes it takes 4 or 5 tries and combinations of
reset/power switch maneuvers to get it to boot (it would be so nice if
it were possible to tell it to go from the "Do you want to erase all
data" screen directly to the rest of the boot process - I can often get
it to that dialog easier than I can get it to boot for some reason..
(I even have a ROM address where an appropriate hook could be added -
00113E04 in the middle of ZapInternalStoreCheck)
Jim Witte
jswitte_at_bloomington.in.us
Indiana University CS
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