Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!hp-pcd!hpfcso!hpfcdc!chuckc
From: chuckc@hpfcdc.HP.COM (Chuck Cairns)
Newsgroups: comp.sys.hp
Subject: Re: Hardware flow control on 9k/800s
Message-ID: <5570646@hpfcdc.HP.COM>
Date: 25 May 91 02:32:37 GMT
References: <1991May22.164645.5002@vax5.cit.cornell.edu>
Organization: HP Fort Collins, Co.
Lines: 21


   Hi,
   I'm not completely sure of the details but I do know that the V.32bis
   (14.4 K baud + compression =  >19.2K) modem bank at HP is going from
   an 800 to 300's with the 8-channel muxes. They are doing that  to get
   hardware flow control ! The muxes on the 800 are not designed to do that.
   Since its a many-terminal machine the OS actually polls versus interrupts
   on RS232.  Overall, cuts down on overhead. If you get REALLY stuck you
   could buy the "real-time interface" RTI card. It has hardware flow control
   but only a 1 char overrun when it shuts off the modem. So the modem
   has to shut off the flow in one character ... in spec ...but touchy.
   It also needs to use a special I/O driver and some associated techniques.
   You actually  program the RTI card in C. Also a rather $$ solution.

   I wish I could think of a better option for you ! I'll think over the Mem
   day weekend and see if I can come up with something. Don't hope too much,
   though it would seem easy, this one is kinda tough since it's not what
   the 800's MUX was designed for.
   Sure you don't have a  old 320 handy ? 
   Regards, cc
   As always my opinions are my own ... not HP's.