> Okay, but my impression of XON/XOFF flow control is this - a device
> will send XOFF iff it cannot buffer any more characters at the current
> rate they are arriving, sending XON when the buffer is at low-water or empty?

You're right. I mixed it up with start/stop-bits. I stand corrected.

> see in my lifetime, but the few I've seen over the years general produce
> some garbage on the screen if the connection is basically there - a question
> of baud, start/stop bits, parity and so on.

I don't know if this is related but I tried connecting a modem to my
DECserver 200/MC a couple of days back and struggled desperately with
it. No matter how I configured the DECserver, it refused to send
anything at all to the modem. Until I took a wild shot and disabled
flow control completely, after which it's been working perfectly fine.

So flow control can cause lots of trouble and it's become a habit of
mine to allways turn it off when I'm playing with hardware that won't 
work.

Someone mentioned a device which you plug in between the devices and
monitor the traffic on, and you're also able to switch a few things
around to try different cables. Such devices are generally a Good
Thing<tm>, but have a habit of costing more then the other devices :-)
(Unless you make one yourself)

And as a side-note; I'm still looking for technical documentation for
the MicroVAX 3500 :-)

-- 
Jonas - http://poledra.coyote.org:8080/~jonas/