CompuServe Messages

In case anybody's interested, here's how I solved it: The Macsbug Reference has a pretty good description of debugging and snooping around device drivers with Macsbug. I basically used the Unit Table address ($11C) to get at the DCE dCtlFlags field for the drivers in question (.AIn, .AOut, .BIn, .BOut). I then tested bit 5, which flags whether or not the driver is open. I sure hope there *isn't* an easier way to do this, 'cause it took me all day yesterday to figure it out :-). If anybody wants the code (MPW Pascal), let me know and I'll email it to you. Steve McDonnell Epsilon, Inc.