The momentary switch does work. D0 only needs to be grounded for about 1-2 seconds for the BIOS to load into memory. This is actually a fairly good way to implement an Xbox Live safety switch. If you're little brother/girlfriend/dumb friend decides to boot your Xbox and go on Live when you're not around, it's not likely they'll hold the button during bootup, and therefore they'll only load the MS BIOS.
@OllieD The reason you have problems with the MatriX is because it's not just D0 that is losing contact, it's the LPC pins, too. It seems that even though the BIOS is fully loaded into memory (so we've been told) there is still some sort of communication on the LPC bus when you run a program. I've done some experimenting...
Boot from LPC, then unground D0: Apps and games run
Boot from LPC, then unplug LPC chip: Apps and games do not run
Boot from LPC, then unplug LPC chip and ungound D0: Apps and games still do not run
Boot from LPC, then replace LPC chip with another (same BIOS): Apps and games do run
Boot from LPC, then replace LPC chip with another (different BIOS): Apps and games do not run
In fact, it seems to me like even though the BIOS is loaded into memory, the .xbe's still need direct access to the BIOS chip. This seems strange, and contrary to what I had been led to believe about the way the Xbox BIOS is handled. I think I might start a new thread about this, to see what others have to say about it.
In summary, the momentary switch for D0 will work, but the chip (or another chip with the same BIOS) must be connected to the LPC for apps and games to run.
This post has been edited by dzv: May 27 2003, 02:04 AM