positions for the status bits of port a and port b are different. To
avoid needing to know which channel the interrupt handler is working on,
shift the status bits for port a into the port b bit positions, and always
check the port b status bits. This fixes using port b, which I neglected
to test before.
- Remember to update the channel's tty structure from the passed in termios
in the param routine.
- Minor style.
With a 1 byte transmit fifo, 3 byte receive fifo, and wierd multiplexed I/O
designed for a Z80 cpu, this chip redefines suckage.
Based on the openbsd and netbsd drivers. Only really works as a console,
modem support is not complete since I can't test it.
