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Flashing Tsop With Lpc Mod?


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#1 illumin8

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Posted 12 October 2002 - 09:51 PM

Hi everyone, I've been lurking for a while but this is my first post. I've been thinking about the possibility of flashing my on-board BIOS with the EvoX 2.5 BIOS, then buying a second Xbox and moving my LPC mod-chip to the new XBox and doing the same thing.

When I read the flashing your TSOP tuturoial, it indicated that an LPC mod-chip didn't allow you to flash the on-board BIOS. Is this still the case? I'm just wondering if anyone has come up with a work-around for this. I like the LPC mods because they're easier to install. I actually know how to solder, but those connections are tiny!

This would save me from having to buy another mod-chip for my second box.

Thanks!

#2 bagel5009

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Posted 12 October 2002 - 09:59 PM

lpc-mods flash the mod chips bios, not the xbox's bios, regular mod chips w/ 11 and 21 wire flash the xbox's bios, but its a lil harder to flash.

#3 illumin8

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Posted 12 October 2002 - 10:02 PM

bagel5009 - I know how the LPC mods work... Basically, when you turn the Xbox on, it initially loads the BIOS from the motherboard. The LPC mod overwrites this BIOS in memory with it's own BIOS that is stored on the mod-chip.

What I'm wondering is if there's a software solution, like an XBE or something that can flash the on-board BIOS without the need for the other type of mod-chip. Once you're running unsigned code this should theoretically be possible, it could just be that it hasn't been figured out yet.

Thanks!

#4 RickH

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Posted 12 October 2002 - 10:21 PM

QUOTE (illumin8 @ Oct 12 2002, 05:02 PM)
bagel5009 - I know how the LPC mods work... Basically, when you turn the Xbox on, it initially loads the BIOS from the motherboard. The LPC mod overwrites this BIOS in memory with it's own BIOS that is stored on the mod-chip.

What I'm wondering is if there's a software solution, like an XBE or something that can flash the on-board BIOS without the need for the other type of mod-chip. Once you're running unsigned code this should theoretically be possible, it could just be that it hasn't been figured out yet.

Thanks!

You are almost correct. The original bios has to be disabled because the LPC mod uses the same address space and two chips cannot reside in the same address space at once. Of course once you disable the original chip then you have no way of getting access to it to program it. Basically you need to have both chips reside in memory at the same time so the mod chip can access the original chip to program it. At this time that is not possible. I think it would take a modification to the MCPX to accomplish this. I believe the bootup sequence looks for the onboard bios and if it doesn't find it initializes the LPC bus which then brings the mod chip online for access. This may sound silly but this large hole in the security system of the X-Box must have been put there for MS to test/troubleshoot the boards, can't think of any other reason for it. LPC mods would not be possible if the system only recognized the onboard bios!!!




#5 bagel5009

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Posted 12 October 2002 - 10:50 PM

QUOTE (illumin8 @ Oct 12 2002, 09:02 PM)
bagel5009 - I know how the LPC mods work... Basically, when you turn the Xbox on, it initially loads the BIOS from the motherboard. The LPC mod overwrites this BIOS in memory with it's own BIOS that is stored on the mod-chip.

What I'm wondering is if there's a software solution, like an XBE or something that can flash the on-board BIOS without the need for the other type of mod-chip. Once you're running unsigned code this should theoretically be possible, it could just be that it hasn't been figured out yet.

Thanks!

no software soulution

#6 illumin8

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Posted 15 October 2002 - 08:51 PM

RickH, thank you for the explanation of how an LPC mod chip works. I understand now why it's not possible. I think you're right also about how MS used the LPC as a "test bed" for different types of BIOS. Working for a major computer manufacturer myself (not going to say which one), I've seen our system's firmware test labs, and the test beds look just like a "modded" game console. Engineers attach traces to the PCBs permanently, and new firmware can be quickly tested by simply attaching the flashed firmware to those traces.

Cheers.




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