> I have already seen the Philips PCF8584 but it only supports a maximum =
> processor bus speed of 12MHz.

The 8584 is the only one I've ever seen.  I researched the part but
have not used it yet.

Can't you force a CPU wait-state on this one peripheral to make it
work?

> BTW can you tell me what is the capacity of an EPROM chip i just found =
> ?? It has the following label on it 27C64A-20 FA (FES5486   8829VD).

27C64 is an EPROM, CMOS, 64 K bits (8K x 8).

> I pressume the access time is 20ns.. am i wrong ??

The 20 usually means 200 nanoseconds access time.