Connects between Z80 CPU and mainboard. I/O Ports for AMSSIO v1,v2,v3 are:
FBF0h AMSSIO Serial Interface [[MC6850|6850 ACIA chip|MC6850]] Control/Status Register (R/W) FBF1h AMSSIO Serial Interface [[MC6850|6850 ACIA chip|MC6850]] Data Register (R/W)
For details on the MC6850 chip, see [[6850 ACIA chip]].