Yeah I was baffled as well. I at least expected some logic in between, but nope... anyway, a quick glance at the socket diagram in the post made me go "I guess", and here are some entirely unfounded, speculative maybe-answers to your questions (I didn't check the data sheets either):
> Voltage levels from the chipset?
Wasn't it just 3.3V at the time (or maybe even 5V)?
> Bios recognition?
Not necessarily? Software-wise, a Pentium is still compatible with a 486, and 486s did not even have CPUID yet (only some later steppings did). The BIOS might have not set some bits in some of the control registers as it would otherwise do, but that does not prevent the CPU from working...
> IO timing diagrams?
That's the hardest one, but remember that this was not a "true Pentium" but an "Overdrive", which is basically a Pentium with a 486 bus interface. And the board does accept 486s.
> Voltage levels from the chipset?
Wasn't it just 3.3V at the time (or maybe even 5V)?
> Bios recognition?
Not necessarily? Software-wise, a Pentium is still compatible with a 486, and 486s did not even have CPUID yet (only some later steppings did). The BIOS might have not set some bits in some of the control registers as it would otherwise do, but that does not prevent the CPU from working...
> IO timing diagrams?
That's the hardest one, but remember that this was not a "true Pentium" but an "Overdrive", which is basically a Pentium with a 486 bus interface. And the board does accept 486s.