>We found that if you insert a resistor (I don't remember what ohm) on the
>line this will keep the break signal from reaching the serial port,
>and thus end the problem.
> I'll try to find out the specific resistor to use and best placement
The equivalent of L1-A (halt machine, drop to ROM monitor) from a
terminal console is BREAK. Unfortunately, turning off the terminal or
disconnecting it is usually interpreted as a BREAK and halts the
machine. Thus, it is not easily possible to turn off the terminal when
the console is not in use, or to use one terminal with many machines via
a switchbox. Suggested solutions include a special cable (on a 4/2xx
CPU, a 4.7K resistor between pins 3 and 25 may work) or modifying the
SunOS serial driver (zs) to ignore breaks.
I hope those having problems using a terminal with a Sun will
experiment with the resistor connection and report success or
failure to the net and James Birdsall for inclusion in the faq.
Finding a way to turn off a terminal used as a console without
crashing to boot rom would be a great advance in computer science,
at least for those using Sun's.