@jessenator Clock buffer chips are pretty common on computer systems.
Imagine a bus with several different devices on it, which operates synchronously. I. e., they're all expected address/data phases at a particular time in a particular relationship. How do you give all those separate chips a concept of time like that?
Obviously, you hook them all up to the same clock. But there are details. It turns out that the drive strength from a single oscillator isn't all that strong. And some chips need the signal doubled or halved for various logicy reasons.
So, clock buffer chips.
A single clock signal goes in. In theory everyone is running off that one signal. The buffer chip takes that one signal, and splits it into several identical signals which are all in phase with each other, to some very small tolerance and each of the chips on the bus gets its own clock from that buffer chip.
Additional fancy things can happen on the buffer like dividing or multiplying the original clock for all or just some of the output clocks. Depends on the buffer chip and the system requirements. It sounds like some components on Wombat are using the straight system clock, but at least the CPU (?) needs a clock signal at twice the bus speed. Hence that 2Q_X signal.
I haven't looked closely at the datasheet for the MC88916DW, and how WomBatman does things, but, for example, on the X500 Power Macintoshes, which have their CPU on a removable card, the clock signal also originates on that card. That way, the CPU card one installs controls the bus speed.
But in practice, the way that is done is that six (6) different clock pins exit the CPU card and go out to components on the motherboard. Every CPU card for the X500 series has a clock buffer chip on board that splits the clock signal at least 7 ways (one extra for the CPU on the card).
On the PPC601 chip, the chip does not have the ability to multiply its input clock, the way later PPC chips do, so if you have a bus speed of 33MHz, and you want the PPC601 to operate at 100MHz, then you need a clock buffer that can supply an X3 clock signal to the PPC601 chip.
Anyway, I didn't realize that the datasheet for the MC88916DW doesn't cover the -55 version. I know it exists because I have a reel of five or 6 hundred of them here. I've been wondering what I can do with them, since they're the slow version. Not going to replace the fast version with the slow version.
Do you feel comfortable replacing that chip? It would be interesting to do thorough speed testing on both machines and then replace the MC88916DWs with the -80 version and see if it makes any difference in the performance.
I think I have some of the -80 on hand. I need to check, but if I do I could send you a couple.