Finally, I have a bidirectional 20 ma current loop between my old desktop PC and the 8/A :) There was another "gotcha"... although the power for both transmit and receive current loops comes from the M8316 in the 8/A, the line driver on the PCL-740 card is *not* isolated from ground even when set to passive mode! The 20 ma was there on mark all right, and no current on space, but the design of the M8316 card interface is such that isolation is required for both the + and - terminals. So I had to whip up a quick optoisolator-based board (although a small fast relay would work for 110 baud, I didn't have one handy and I may want to download large files at a faster rate). Anyway. Now I have a set of files (AJRL**.BN) and need to download them to the 8/A. First I have to toggle in the RIM loader, of course. But are these binary files in RIM or BIN mode? If the latter, can I use the PC to send the BIN loader over to the 8/A? thanks Charles