⚠️ According to the old architecture photos there are two bus modules inside PSXCPU - one for external buses and one for internal buses and cache. The suspicion that the module for handling internal buses and cache is actually COP0. But so far it is not very clear, so I will leave this note here.
COP0 + Internal Bus and Cache Controller.
TBD.
Mysterious register 0xFFFE_0130.
