On Tuesday, March 15, 2011 20:16:28 Cranky Frankie wrote: > I think I fixed my netbook shutting down problem. This may be unique > to the Acer Aspire One netbook, however. > > Researching it further I found recommendations for upgrading the bios > to v. 3310. I had done that weeks ago, but there was a part I had > missed. After the bios update, you have to unplug the netbook, remove > the battery, and then hold the power on switch for at least 2 minutes > to clear the mobo. The instructions were specific - one minute would > not work, had to be two. Don't know if this drained the caps or > whatever, but it seems to have worked (I'm hunting and pecking on > battery power alone on the tiny keyboard right now).
My understanding of the way that BIOS chips work is that there's a FLASH RAM area that you program, and a separate battery-backed area with the same information which gets copied into running computer RAM at power-up. When you re-flash the BIOS, you're copying over the "master" copy in the FLASH RAM memory of the BIOS chip, but this does NOT automatically get copied into the battery-backed RAM of the BIOS chip that is actually USED when you power up the computer. This explains why you need to go through the special procedure to drain all power -- because that's the only way to remove the battery-backed RAM copy of the BIOS in order to force the "master" to be copied over into the battery-backed RAM portion of the BIOS again so that it's used for bootup. The BIOS uses a CRC checksum algorithm, and if the checksum stored doesn't match the expected CRC calculated from the algorithm, that's what triggers the copying procedure from "master" to the battery-backed RAM area. The battery-backed BIOS RAM also contains any user BIOS choices, so if you had changed any BIOS settings you'll likely have to go fiddle with those again. What isn't clear is what holding down the power button actually does. What most motherboards in Desktop PCs do is to have a jumper to allow the user to short the power going to the BIOS -- and I think what that actually does is short the +3 Volts from the lithium backup battery to ground during the time the jumper is set to "clear". I think that's likewise what's going on with the power button for this laptop -- while you're holding it down for a couple of minutes, the lithium BIOS backup battery is being shorted to ground. It's likely that the BIOS chip /also/ contains it's own internal "temporary" backup power source (a capacitor, or possibly even an internal lithium battery), which is why you have to hold down the power button for longer than you'd expect. There are chips that actually have a lithium battery built into them internally, such as those found in Real-Time Clock (RTC) chips -- and these also usually come with a RAM area that is battery-backed with the internal + external backup battery. This is why I'm not sure if you might actually be shorting a lithium battery that's internal to a chip or not when you're holding down the power button. The point being here is that you probably don't want to do this too often, even though it is occasionally necessary. > Well, unlike many computer PITAes, this one seems to finally be fixed > (and I'll make sure to keep the dust out of the vent holes too, > thanks). Glad it's fixed -- that's what matters. -- Chris -- Chris Knadle [email protected] _______________________________________________ Mid-Hudson Valley Linux Users Group http://mhvlug.org http://mhvlug.org/cgi-bin/mailman/listinfo/mhvlug Upcoming Meetings (6pm - 8pm) MHVLS Auditorium Apr 6 - Introduction to IPv6 May 4 - Inkscape Jun 1 - Zimbra
