On Thu, Oct 9, 2025 at 12:32 PM Nigel Johnson Ham via cctalk < [email protected]> wrote:
> On 2025-10-09 13:34, Paul Koning via cctalk 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. > > > > paul > > > I had one once. AFAIR it is just a serial switch to access different > peripherals from one port on the CPU. Possibly switchable by control > sequences. That was 35 years ago though so I am not sure of setails! > http://www.bitsavers.org/pdf/dec/rainbow/ms-dos/AA-DY84A-XV_Rainbow_Using_the_Mini-Exchange_Oct84.pdf tells how to use it with a DEC Rainbow. So all the ports are RS-232. It was used to share Printers and modems to the Rainbow (though modems had weird restrictions iirc). I don't know if the protocol has been reverse-engineered (likely it has), but the MS DOS 2.11 programs are small. Warner
