I recently got one of these. Universal JTAG, it supports both buffered and unbuffered.

Question is: I have several devices that have a JTAG port and would like to do some snooping around. I know how to hook up a few of them because of various guides on the web, but what if the device has a JTAG port but no documentation whatsoever (like the B&W Tek 473's).

How does one determine how to configure the thing? Does it really matter, and what happens if i run unbuffered on a buffered port? Trial and error?

Or am I worrying about nothing?