[Second serial port on a PDP11/05] > Curious: what if the built in one were > faulty, or if you wanted to use rs-232 > instead of current loop?
IIRC the 11/05S has a way to disable the built-in console port (fit a wire link on one of the boards?) the original 11/05 doesn't. There must be a way to do it by cutting/jumpering but it is a mess.... Therefore, if the built-in port is faulty it is going to be a lot less work to fix it than to disable it and add a DL11 Heck, the entire 11/05 CPU is only a couple of hundred ICs, the serial port is going to be a small fraction of those. It is not going to be hard to figure out. As for the physical interface, firstly the OP mentioned a teletype, which to me suggests current loop anyway. If you need RS232 then either pick up TTL level signals on the CPU board and add level shifters (very easy, but makes the machine not original) or make a current loop to RS232 interface (not exactly difficult either). I think both are less work than disabling the built-in port. -tony - John
