DS3100/dc0 support for modem control

[Timo Lehtinen]

The dc(4) man page (in ULTRIX V3.1D) says that the serial line controller
on DECstation 3100 and 2100 only provide partial modem control. Could
anyone enlighten me as to what functionality specifically is missing ?

I'm writing a program which needs to sense whether Carrier Detect is on
and can't figure out how to do it. For instance

	ioctl(fd, TIOCWONLINE); /* wait for carrier */

never blocks regardless of whether I have a cable on the port or not.

Is it me or the dc0 ?

Any help much appreciated,

Timo

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Timo Lehtinen			Internet:	ttl at sti.fi
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