[rescue] Break signals [was: Booting from LOM?]

[Scott Newell]

>It shouldn't be pulling the cable.  It should be turning off the terminal
>while the cable is still attached.

Interesting.  Could it be the terminal's line driver burping as it powers
down?

I've just grabbed the datasheets on the UC5170/5180 pair, and it appears
the Sun set the IPX to output a logic 1 (idle line) in failsafe mode, which
would _not_ be a break signal to the UART.  I can't tell what the receiver
will do to a grounded input without doing some tests.

Maybe I'm just spoiled--the MAX202 family parts, which I usually use,
guarantee a logic 1 (idle line, not a break) output for open and grounded
RS-232 inputs.


newell