"Johnny" == Johnny Billquist <bqt at softjar.se> writes: Johnny> I wonder why you can't set it from NCP though? Weird if they Johnny> have the functionality, but no "normal" way of enabling it. Probably history. I created the async DDCMP driver when I was doing the (unreleased) PRO port for RSTS (9.6 originally). I handed it to RSTS development, and they integrated it into the release. But I personally never did the NCP work. Probably because it wasn't familiar code and it would have been a lot of work. Instead, I just wrote a little 10 line utility to issue the line on/off syscalls to the kernel. Johnny> Way fun, and impressive. Thanks for that piece of information Johnny> and history. I guess they didn't see much need of DDCMP Johnny> support in RSTS/E at that point. How did you select which Johnny> serial port it would use, by the way? Or was this only done Johnny> for the PRO? Hmm, I guess it could have been passed in in Johnny> the syscall... There is an "assign" syscall (which normally in RSTS means "reserve this device for me even when it's not open") which binds a ddcmp driver pseudo-device unit to a tty device unit number, via a syscall parameter. So you could have, say, up to 8 ddcmp ports, and those could be bound at runtime to any of your terminal ports. paul