Ah the x2xx motherboard architecture.....a classic of enginnering. 8 bit 16 bit and 32 and 64 bit buses living together with no hardware bridges.

Left 32 and Right 32.

The processor runs a 75 MHz, while the motherboard runs a 37.5 MHz.....

Then the GPU, stolen from the Quadra 630 requires a 33mhz Bus, 32 bits wide.

The Comm slot bus is 10 MHz bus, 8 bits wide.

32-bit PMMU, same as 630, runs at motherboard speed.

Processor Bus 64 bits, 37.5 MHz

Network/SCSI/audio/ADB L32, 10 MHz

Memory Controller R32, 33 MHz

Graphics Cont R32, 33 MHz

IDE/Video/TV R32, 12 MHz

And there were no hardware bridges between left and right 32. It was done right on the CPU, using this equation in ROM:

37.5 = 3/2 * 25 12.5 = 1/2 * 25 10 = 2/5 * 25 33 = 4/3 * 25

And some ROMs were bad, making them extremely nasty.