One way to define :

Multiplexed : Address and Data share the same port and you smartly extricate the two use the ALE clock. Saves port pins when accessing code from external RAM.

Non Multiplexed : Address has its own port and Data has its own port. They dont belive in sharing the same ports. I think that the Z80 MCU had this kind of bus - but my memory may be bad...

This looks too funda a query. Is that what you meant ?

Raghu