3c503 etherus interruptus

Randy Bush news at m2xenix.psg.com
Mon Feb 4 09:59:56 AEST 1991

I am having problems with 3c503s interfering with serial ports, both in Xenix
and MS-DOS.  I believe it has to do with interrupts. 

I can't RTFM, as I do not have the documentation for the 3c503s, having gotten
them at a discount shop which buys by the carton.  As far as I can tell (aided
by the NCSA notes), the 3c503 (as opposed to the 3c501) has no jumpers for
interrupt or DMA address selection, but controls these by software.  My sad
story is as follows (sounds of violin are heard):

Xenix (2.3.3 and TCP 1.0.1b with all the latest XNXs)

When TCP is installed and configured, it runs just fine (name service,
resolver, and all), but tty2a/tty2A is dead as a doornail while tty1a/1A is
fine.  Note that tty2a uses Int-3, and tty1a uses Int-4.  The 3comB was
configured (at device install time, mkdev 3comB) to use interrupt 2.

I tried a kernel with the 3com configured in but not starting TCP (by not
starting any of the Streams or TCP deamons and not running ifconfig) but still
no go.  If have the 3comB driver in the kernel at all, then tty2a/2A does not
work, although tty1a/1A does.


If I use NCSA ftp or telnet with CONFIG.TEL saying to use Int-2, both of the
serial ports (COM1: and COM2:) are useless (by my interrupt-driven FOSSIL
software) until I power cycle the box (no reset button available).

The same software with a 3c501 jumpered for Int-2 causes no problems.

So what am I doing wrongly this time?


Randy Bush  / news at psg.com  / ..!uunet!m2xenix!news 

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