High folks.  I'm running the sources as of January 16, 1994 on a
486DX2 with 16MB of memory and two 16550A UARTS.  I have attached a
terminal to tty01 and am using it to login and conduct my business.  At
very irregular intervals, the tty port locks up and doesn't accept input.
If I login to the machine via the network, my login session says it is
happy and that I'm going about my business with no glitch.  My logins
usually subscribe to some messaging scheme and, when one of these messages
gets sent, my ty port wakes up, sends me the message at the terminal, and
accepts input again.  This problem seems to occur most when I walk away
from my terminal and leave it idle.
	My question: Is this a case where the tty driver doesn't wake up when
it gets an interrupt from the serial port or is there something wrong with
the hardware?  There are no messages in /var/log/syslog about stray
interrupts or silo overflows, so I believe the interrupts are getting
serviced in some fashion.  Unless they're not happening at all.
One other thing, the last modification time doesn't change when I pound on
the keyboard of the terminal.  I forgot to check last access time.  It does
change when stuff goes out the terminal, however, and then, of course, when
I type on it.
	Finally, not all strings sent to the tty port wake it up.  I'm not
sure which strings do, but perhaps this is a case of the tty driver eating
certain characters and not quite swallowing them whole?  

	I'm running a vt100 terminal at 9600BPS, even parity, 7 data bits, 1
stop bit, and I'm running the window program on top of that.

	Any suggestions as to the cause of the trouble would be most
appreciated.
-thanks
-Brian

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