mangler@cit-vax.Caltech.Edu (System Mangler) (03/06/87)
Our Vadic VA4224 rack-mount dialout, which works fine with over 25
UUCP sites, refuses to originate a connection to an AT&T PC7300.
I dialed the modem by hand from a terminal while listening on a
telephone handset; the remote PC7300 would answer, and whistle,
then the familiar 1200-bps squalling sound came on and the modem
reported "ONLINE". A second later, the phone hang up. It was
consistent, every time, and no login prompt ever appeared.
My Vadic Maxwell 2400V talks to this PC7300 just fine. The
VA4224 uses the same chipset (Rockwell), why can't it talk too?
A Rev-level problem? (VA4224 has Rev. F, 2400V has Rev. G).
What am I missing? Is it one of the myriad switches/straps?
There are about 2^30 combinations...
Don Speck speck@vlsi.caltech.edu {seismo,rutgers,ames}!cit-vax!speckjhc@mtune.UUCP (03/07/87)
In article <1950@cit-vax.Caltech.Edu> mangler@cit-vax.Caltech.Edu (System Mangler) writes: >Our Vadic VA4224 rack-mount dialout, which works fine with over 25 >UUCP sites, refuses to originate a connection to an AT&T PC7300. Early versions of the modem chip used in the UNIX PC, among other products, were very strict about the amount of deviation allowed from the fundamental comms frequency, which is published in some standard or other. I understand that the allowed amount was bang-on the standard. Certain other modems do not meet this standard. The problem is exacerbated by the fact that the 212 (the standard!) will function perfectly happily with massive amounts of slop in the speed. Newer chips allow rather more deviation. In addition, this modem chip is really fanatical about getting a full stop bit - shaving of these will result in totally unreliable transfers (they alarm out and die). -- Jonathan Clark [NAC,attmail]!mtune!jhc My walk has become rather more silly lately.