What is this WEIRD board I found at TCF

[Joe Wood]

In article <1990May22.031339.1262 at celebr.uucp> jbm at celebr.uucp (John B. Milton) writes:
>I bought a board from a vendor in the flea market at the TCF (Trenton Computer
>Fest). It is a full length 8 bit PC card, with three RJ-45 connectors, a bunch
>of WE (Western Electric) chips, a 68000, ROM, RAM and I/O. The three phone
>connectors are labeled, top to bottom, PHONE, LINE and OTHER, but on the board
>they're labeled PHONE, PBX and AUX.
 
>If anyone can tell me what this is and where I can get software, I'll be
>happy.


Well, John, it looks like you got ahold of some DCP interface cards for
the AT&T 6300 (DOS box) PCs that were used in the AT&T PC-PBX Connection.

These cards with the appropriate software will turn your ordinary PC and
2500 telephone set into a modern DCP terminal (spell telephone).  All
sorts of good features are available such as incoming caller identification,
as well as the usual call hold, transfer, and conferencing as well as
repitory dialing.  That's the good news.


Here's the bad news.  They only work off AT&T System 75 and System 85
PBXs or the Definity Generic 1 and Generic 2 PBXs.  So these would
only be good for use at work in a location with an AT&T PBX or if you
happened to have a System 75 in your home. :-)

The DCP protocol is very similar to ISDN BRI and predates it.  It is
a 2B+D protocol but incompatible with BRI at the bit level (8Kbps
D channel versus 16Kbps D channel, etc.).  It has the potential to
give 64 Kbps clear channel transport of your data (DCP Mode 0),
but is practically limited to 19.2 sync/async (DCP Mode 2).

I verified this by looking at a NIB UNIX-PC DCP card I have.  It
has all the same chips.  I don't know anything about the commercial
availability of the software for either the DOS box or the UNIX-PC.

The three connectors thus are for your telset, PBX line, and pass thru.
AT&T bulding wiring doctrine uses 4 wires for the DCP (locally powered
terminal - you can power the non-display terminals from the wiring
closet.) and passes the other 4 wires through for a daisy chain.
Thus you can run Starlan-1 (I don't know about Starlan-10) or ISN LDMs
in the same 8 wire sheath from the wiring closet.  RS-232 is not compatible
according to the spec.


Joe Wood
jlw at lzga.ATT.COM