On 8/22/05, Dwight K. Elvey <dwight.elvey at amd.com> wrote: Yes, if I can't find any info (which it looks like is going to be the case) I will have to reverse engineer it. The protocol sniffer I use is "snooper" from debian... it uses two real serial ports and bridges them through software while showing the traffic in hex on-screen. It also shows the flow control lines. Of course clipping onto the leads as you did will give more accurate results, but if the protocol is largely request/response oriented a man-in-the-middle type snooper should be good-enough. What I expect to see is a lean packet around a serialized form of DOS software interrupts. But I don't know all that much about DOS so I don't know yet how the redirector works but I suspect that is the key concept to understand. Aside from the data protocol, possibly the flow control lines may be used for something when present. Anyway, just have to get out the tools :-) Thanks, -- John.