Do modern machines even run a POST test at all, or are there other standards? After firing up a Linux machine and dumping the first meg of memory address space, it clearly contained some of the BIOS code. [Alessandro] looked at a disassembly of the BIOS update image and saw a similar structure, with POST code data sent to port 0x80 just like machines of old.
But instead of an ISA CPU bus, we have the Low Pin Count (LPC) bus which is used to hook up the ‘super IO’ functions, controlling things such as fans, temp sensors, and other system management functions. It also serves as the connection for the TPM feature, which usually appears as one of the motherboard connectors intended to be user-accessible. It turns out that POST codes can be accessed from this point with an appropriate POST card that can talk LPC.
[Alessandro] demonstrates his faulty motherboard dumping POST codes encoding for a CPU error, giving at least somewhere to look to debug further. This all goes to prove that even though a modern PC may seem totally different from the first PCs from any viewpoint, there still are considerable vestigial remnants baked in there. After all, if it works, then there’s no need to change it. We’re no strangers to PC hacks, here’s a committed hacker who after upgrading the RAM beyond that supported by the motherboard, was determined to make his machine boot windows, no matter how much it complained. And won.
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