"Johnny" == Johnny Billquist <bqt at softjar.se> writes: Johnny> Paul Koning wrote: 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. Johnny> Way nice. In RSX, you need to reserve the whole controller at Johnny> netgen, and no ports can be used by anything else than DECnet Johnny> if you set it up. DECnet/RSX has its own device driver for Johnny> the serial port cards. For RSTS it's a connection from the regular terminal driver to the DDCMP driver, which acts as a sort of coprocessor. Linux has the same notion; it's called "line discipline" if I remember right, and is nicely modular. That's where DDCMP would go if one were to do it for Linux. paul