Well, nobody else is responding (publicly) so I'll take a stab at it. At 5:23 PM -0800 3/10/03, Christopher McNabb wrote: I'm not aware of such a function either. Uh, I don't have my DEQNA manual in front of me at the moment, but are you sure that's correct? Usually the CSR implements bits that control the module itself and provide status information. The MAC address should be readable (and writable too), but through some specific function code to the device. In any event, the correct sequence of commands can surely be obtained from the manual. [I'll probably get flamed here, but I'll proceed anyway. My experience is primarily from RSTS V7 and prior. While I did write system KBMs, run-time libraries, etc. However these were in user mode, not kernel mode. Never did get around to writing the virtual disk driver I wanted to. DEC came out with their own in V8 or V9.] In order to talk directly to a device under RSTS you need to be in kernel mode, not user mode. I am not aware of a RSTS-native way to do something like RSX or VMS connect-to-interrupt directives or the like. Similarly there is not a (published) way to map I/O space to user space. This is really the kind of thing you need to accomplish what you are asking. I imagine it could be done, but you'd have to do some kernel-mode hacking to accomplish it. Afraid that's the best I can offer. You might check the various internals manuals at <http://elvira.stacken.kth.se/rstsdoc/rsts-doc-v80/> and see if that gives you any hints. If you do figure it out, please post the results. John