If memory serves, a standard ROM chip doesn't just drop into the Mac 128, one pin needs to be jumpered for it to work. Easier and more certain to work if you have the genuine Apple chips. I think pin 1 of a 27C512 EPROM has to be lifted from the Mac's socket and a jumper wire run to pin 28 (directly opposite) because PROMs like Apple used have an active low chip enable and EPROMs are active high. Or something like that. I definitely remember putting jumpers on all the Beck-Tech ROM upgrades.