Using the DigiComm multi-port board with SCO Xenix

David H Close compata at cup.portal.com
Thu Aug 17 13:30:58 AEST 1989


David Raines recently comments:

> I believe they [Digiboard] also have an adaptor for RJ-45 connectors,
> which would be nice, but I have other machines with other IO boards 
> and every manufacturer seems to have their own idea of what RJ45 
> pin configurations should be.  (ARE YOU READING THIS Digiboard,
> Bell, Arnet, Anvil, etc. etc....).

> Actually, Digiboard has the closest setup of all boards that
> I,m aware of, to what I,d like to see. If the pins were symmetrical, then
> the same adaptors could be used for either modems, computers, terminals,etc.
> by simply flipping the wire. 
> 	Example:  	1 DTR  ---------
> 			2 GND  ------  |
> 			3 RTS  ---  |  |
> 			4 XMT    |  |  |
> 			5 RCV    |  |  | 
> 			6 CTS  ---  |  |
> 			7 GND  ------  |
> 			8 DSR/DCD  -----
> Any thoughts?

Yes.  Many terminals operate just fine on three wires.  It's a shame to 
require a 6-or 8-wire cable to support these devices.  4-wire IW cable is
cheap and widely available.  Tools to crimp the connectors are cheaper than
RJ45 also.  It seems to me that, if RJ45 is to be used, the TxD, RxD, and SG
pins should be grouped in the center so that RJ11 connectors and cables can
be used when appropriate.

The example shown for Digiboard (which I cannot independently confirm)
almost makes it but SG is too far out.  I've the same complaint on the
Bell Tech boards I've used.  Surely, the crosstalk problem isn't so bad
that these three signals must be so widely separated?

Dave Close, Compata, Arlington, Texas
compata at cup.portal.com



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