modem trouble

[Vernon Schryver]

In article <1991May25.021412.6558 at gpu.utcs.utoronto.ca>, topix at gpu.utcs.utoronto.ca (R. Munroe) writes:
> I'm having a bit of strange trouble with a Hayes Ultra 9600 Smartmodem
> hooked up to a PI 25.  I can dial out O.K.  I also have no trouble
> dialing in - the modem connects, I get my login prompt, etc.  The trouble
> starts when I issue a command who's output is more than 5 or 6 lines.
> For example, if I issue an 'ls' command, the first 4 lines of my 
> directory listing print out fine.  The next line is completely garbled
> and the following lines don't print.   ....

I assume a Hayes Ultra 9600 is a v.32 compatible modem.
You don't say what sort of garbling happens.  However, I bet it's missing
characters.

I bet the problem is that:
  -your modems are talking to each other slower than to the IRIS
     +modems using 2400 bits/sec (v.22) and IRIS-modem interface is at
	9.6 or 19.2 b/s
     +modems using 9600 bits/sec (v.32) and IRIS-modem interface at 19.2 b/s
  -the modem is not doing any flow control because
    +the cable is wrong  (not 7 correct wires)
    +not using the ttyf* name
    +modem is not capable of or configured to use RTS/CTS flowcontrol
    +IRIS and/or modem not set to use in-band, XON/XOFF flow control
  -as a result of the speed mismatch, the IRIS is overrunning the modem buffer.

Please note that fix-hayes is for the ancient "Hayes 2400 Smartmodem."
I have no idea what effect it has on this new modem.


Vernon Schryver,   vjs at sgi.com