A major difference between the A3000 expansion bus in Zorro II mode and
the A2000 bus is the absence of the signals /VPA and /VMA, which comprise
the 6800/6502 peripheral support mechanism that's part of the 68000 bus
interface.  This mechanism was never a supported part of the Zorro II
specification, however, and it should not be used by any PIC.  Any Zorro
II PIC that depends on /VPA or /VMA will not work in the A3000 bus.  It
was, in fact, impossible to legally use this on the A2000 bus.  The
 E clock  is, however, supported on the Zorro III bus, though its duty
cycle may vary in some situations.