dtack_decoder.pld

GAL22V10
DTAK_DEC

NAS ROM DUART NC EXP DTKDUART DTKEXP IACKEXP IACKDUAR NC NC GND
NC NC NC NC NC NC NC NC NC NC DTKCPU VCC

/DTKCPU = /DUART * /DTKDUART
        + /EXP * /DTKEXP
        + /IACKDUAR * /DTKDUART
        + /IACKEXP * /DTKEXP
        + DUART * EXP

DESCRIPTION
Mackerel-08 v1 - DTACK Logic

When either the DUART or the expansion bus are selected, pass their DTACK signals to the CPU,
otherwise, assert /DTACK all the time

When either the DUART or expansion bus IACK signals are asserted, pass their DTACK signal to the CPU