Fast ZII mode or ZorroIV is just an overclocked Zorro II without DMA capabilities.
It was a quick, inexpensive and faster design than ZorroII because it required no Buster chip (hence no DMA capabilities).
It is very usefull and backwards compatible with 95% of the Zorro II cards out there.
It has the advantage that if the ZII card is capable, it can run much faster than the normal specced ZII cards.
Cards that do not work are between others, the A2091 and several GVP SCSI interfaces.
Micronik, MacroSystem and Elbox implemented this ZIV non standard bus expansion in many of their busboard designs.
Also many companies created several ZII cards that could operate on this Fast Z2 mode: DCE, MacroSystem, Village Tronic, between others.
