On Thu, Oct 9, 2025 at 2:57 PM Ron Pool via cctalk <[email protected]> wrote: > > I was poking around eBay and up came a listing for a DEC "mini exchange", > DFMSA. What is that? The name doesn't sound familiar. It looks like a box > with a bunch of DB25 > connectors on the back, but that doesn't help much. > > See page 4.50 of > https://bitsavers.trailing-edge.com/pdf/dec/catalog/Digital_Networks_and_Com > munications_Buyers_Guide_198710.pdf > > From that page: > > The Mini-Exchange is a microprocessor-based, standalone, asynchronous > circuit switch designed for local connection of up to eight of Digital's > personal > computers...
I think I have one of these. I fiddled with it when I first got it, but haven't had a reason to pull it out recently. >From what I recall, you sent specific control codes either from some sort of hot-F-key memory or by using DOS utilities like XATTACH and XDETACH to switch ports (I never fiddled with the DOS utilities). It could be interesting to use as an async traffic switch for file transfer programs like Kermit, I don't remember how many simultaneous connections it supports. Here's a usage manual I pulled up after a quick search. http://www.bitsavers.org/pdf/dec/rainbow/ms-dos/AA-DY84A-XV_Rainbow_Using_the_Mini-Exchange_Oct84.pdf Cheers, -ethan
