FC7Fh [[Z80-DART/Z80-SIO chip|Z80 SIO]] Channel B Control/Status
For details on the Z80 SIO, see [[Z80-DART/Z80-SIO chip]]. The circuit supports both Channel A and B. However, for channel B, only RX/TX signals are implemented (though with some modification, one could add a third MAX232 for also supporting RTS/CTS and DTR/DSR).
The COM8116 chip is driven by a 4.9152 MHz crystal. Selectable clock sources are: