4 ms·

I'm utterly baffled that this worked. Ignoring an entire border of pins? Voltage levels from the chipset? Bios recognition? IO timing diagrams? I kinda don't b

• Zarathust 5y ago
  However, looking at the Pentium Overdrive pinout the extra row of pins doesn’t seem to be at all essential. There is a number of extra power points and some signalling pins to support L1 cache coherency when using write-back. Nothing too much to worry about. Uh... sure, if you say so.
  • raverbashing 5y ago
    Yeah, if I well remember from similar Intel manuals, no power/GND pins are marked as optional, quite the contrary Though, given how it might be using low power (and maybe with some overdrive adaptor quirk), it might have worked this time
• anyfoo 5y ago
  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.