Whoa. That is
way too weird.
I was going to come and say "hey, you're lucky you don't have the boot chips from the Power Express PowerMac 9700 prototype... they were buggy and didn't work
Then, I looked at the picture, and was going to say whoaaaa.... that looks an awful lot like the Power Express motherboard.
Then I read the above comment, and was like, oh, right. That's because it is the Power Express motherboard.
How ****ing outlandishly unlikely is that?
But yeah, it's on the logic board. The light brown slot is actually the PDS slot where the processor goes, the darker brown one is the ROM slot, though the PEx and 9600s had the ROM on the MoBo, not in a DIMM slot (I've actually got a 9600 a few feet away from me). Apple had ROM slots on all their old PowerMacs, whether they were soldered to the board or not. Not sure why.
The big white slot is actually a 64-bit, 50 MHz (yep... 50) PCI slot (for extra bandwidth) intended for an AV video card that was canceled along with the PEx.
They wouldn't look like those, of course.... those are flash ROMs, since the developers were frequently making changes to the toolbox, OpenFirmware, etc. The ROM on the MoBo would just be black chips.