I login to my second Sun3 via cu on ttyb to its ttya.
  (it is headless)
  
  After a reboot, there is usually a bunch of ^G, or perhaps just parity errors, which
cu complains about with a bell. I get a bunch of them.
  This evening, each time I logged in to my headfull machine, I got locked up. The
cu started automatically, and got lots of bells. This seems to crash the machine.
  I L1-A'ed each time (since the machine locked). I had looked at the trace. It was
waiting for a serial port to drain. I have just clued into this meaning the keyboard.
What would happen if the keyboard was busy beeping? Would the system hang?

  I won't be cu'ing again until I figure out what is up, but I *do* need the console
of that system to reboot *it* now and then.