console multiplexor

At 01:52 AM 10/4/00 -0800, Mike Ford wrote: Well in this case I was talking about a multiplexor for DEC RS-423 consoles. I suppose this would have some number of MMJ ports (no doubt an odd number :-) and one would go to one's "console" and the others to the other machines you are controlling. Clearly the simplest solution is a 6PnT rotary switch, some cables wired up with MMJ plugs crimped on their ends. I'm planning to build one of these as I have all the parts and that will get the console going on the micro-cluster. Somewhat more clever is to use a CMOS switch and some push buttons with LEDs and get the whole thing to be 'lectronic. You could have an LED indicate which console was selected and another to show traffic on that console. If I get ambitious this is the first one I'll actually build (skipping #1 above). However, if you're willing to be really clever then you can do much better than this. I've got a nice color terminal (the Link MC70 although its color is a bit unstable these days :-() or I could use a DEC VT340 (probably the actual version for display) and you could, with a bit of smarts and some buffering take output from the RS-423 lines, and prior to forwarding them on to the terminal you could inject ANSI color codes on/off. This would make the output from each console a different color. (keeping them straight is of course the challenge) If you are really clever you don't allow one console to interrupt another mid-line either. I've got an old single board Z80 system that could probably do this, or I could wimp out and use a CPLD feeding a Scenix chip. Anyway, all that aside. If you come across a box that has a selector switch on the front and a row of MMJ's on the back, that is probably what I'm looking for :-) --Chuck