Moogle!
Experienced Member
I was playing with my big discrete logic board 486 again, and discovered that an unmarked jumper selects how the oscillator crystal is used. The normally fixed position that the board was sold with runs a 66Mhz oscillator which is divided somewhere and appears as 33Mhz at pin C3 on the CPU socket. The other position, (I had to desolder the the solid wire jumper and solder pin headers to the motherboard so I could use the other position), sends the full crystal frequency to C3. As far as I can tell, there is no difference at all between 2/66 and full 33, so why was the board designed with the clock divider circuitry in the first place? There is no further clock division anywhere else as far as I am aware, and the ISA bus has its own oscillator, a socketed 16Mhz and a soldered down 14.318 Mhz.
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