asfy@vax5.cit.cornell.edu (05/23/91)
We have an HP 9000/825, with a 98196A 6-channel mux card installed. We're running HP/UX 7.0. We're looking into the possibility of installing a US Robotics HST modem on this machine, and it would be best to use full duplex hardware flow control on the RTS and CTS lines. I don't see anything in the manuals-- does anybody know if it can be done? --jh
chuckc@hpfcdc.HP.COM (Chuck Cairns) (05/25/91)
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.
zap@indic.se (Jonas Petersson) (05/26/91)
In article <1991May22.164645.5002@vax5.cit.cornell.edu> asfy@vax5.cit.cornell.edu writes: >We have an HP 9000/825, with a 98196A 6-channel mux card >installed. We're running HP/UX 7.0. We're looking into the >possibility of installing a US Robotics HST modem on this >machine, and it would be best to use full duplex hardware flow >control on the RTS and CTS lines. I don't see anything in the >manuals-- does anybody know if it can be done? I can tell you one thing: It works, but in a strange way. I have successfully used HST modems on a 825/835 (upgraded lately) and when it works, it works like a champ. However, sometimes the modem refuses to answer. It didn't happen too often and I usually have 'ct' call me back anyway after loggin in on a different line. As we bought a 425S for a cluster server instead, I've noticed that a similar (same?) problem is repeatable (on all tried 3/400 series MUXes): * RTS is lowered at boot time and by 'cu' which makes the modem refuse to answer. I've figured out two workarounds: 1) Run a program that raise RTS now and then. Kermit works for instance. 2) Configure the modem to ignore RTS in some way (there is a zillion soft switches as you know). This wasn't needed on the 8x5 though. Neither is very good since 1) really shouldn't work, and 2) isn't too nice for HW flow control - seems to work though. I've reported this to HP Sweden, and they tell me that it is supposed to be like this - that is: 'cu' *SHOULD* leave RTS low on exit regardless of what it was when 'cu' started. How anybody should be able to log in after that beats me... 'cu' was this way in 7.0. Good luck / Jonas Petersson -- /// "Are you THE Zaphod Beeblebrox ????" # zap@indic.se __ /// # Air Quality Surveillance \\\/// "No, just A Zaphod Beeblebrox. # "I can feel it coming \/// Didn't you hear - I come in sixpacks !" # in the air..."