[net.unix] CXR problem with a modem

chris@umcp-cs.UUCP (08/12/84)

There are lots of possible solutions, but we happen to like one
in particular:  add another major device number that allows opens
without waiting for a carrier, and simultaneously suspends normal
opens.  In fact we use just such a modified driver for our UUCP
dialout.  Our 3 Vadic 3451s can be (are) used for dial in and
dial out ``simultaneously'' without modifying anything but the
kernel.

If there is enough interest I'll post the changes to the 4.2BSD
dz.c.  (Similar changes in dh.c accomplish the same thing for DH
lines, and I'm sure the same can be done for DMFs; we just happen
to have the Vadics on DZs.)
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci (301) 454-7690
UUCP:	{seismo,allegra,brl-bmd}!umcp-cs!chris
CSNet:	chris@umcp-cs		ARPA:	chris@maryland

lui@ucla-cs.UUCP (08/17/84)

I am using a Racal-Vadic VA212 modem for both dial-in and dial-out access.
One curious thing about the terminal driver on UNIX is that in order for
the open call on a tty to complete, the CXR line must be on (that is there
must be a carrier on the modem line). However, this cannot happen until
the modem can be told to dial out and establish contact with a remote
system. Is there any easy way to fix either the tty driver or open call
so that it doesn't wait for CXR?


    Stephen Lui
    UCLA Program in Computing
    7220 Mathematical Sciences
    Los Angeles, CA 90024
    (213) 825-5101

    ARPA:  lui@UCLA-LOCUS.ARPA
    UUCP:  ...!{cepu,ihnp4,trwspp,ucbvax}!ucla-cs!lui