🚀 go-pugleaf

Michael Sanders (Michael@expl.demon.co.uk) wrote:

> > It is my belief that most ISDN TA's will emulate a Hayes modem, and can be
> > plugged into your RPC, leaving the software oblivious to this fact. Whether
> > Demon will support a digital connection at their end is another matter
> > entirely...
>    
> Sorry but isn't this wrong?

Well the BT Ignition TA that (usually :-) sits on my desk looks exacly like
a modem.  AT commands etc.

I use it to connect to demon too...

> The whole point about ISDN is that its a digital transmission network
> therefore the conventional MODEM-PSTN-MODEM setup is useless because you
> don't need to convert to analouge, you just send the straight digital data
> stream down the line.  
> 
> The TA (Terminal adapter) connects your computer to the ISDN line at a very
> fast data rate, upto 128Kbaud per sec if using X25 and both data channels on
> ISDN 2! It also dials the number and sets the line up (using the D channel
> I believe).

Correct so far...

> Therefor to use ISDN you need a suitable TA card to link
> computer to ISDN and a software, like ISDN manager on the Mac, to control
> said TA.  Your comms s/w must also support the ISDN card.  
> 
> I may be wrong but I didn't think there was any s/w on the Acorn that could
> do this, I hope I'm wrong!

You are wrong I'm afraid.  You can get internal or external TAs just like
modems.  Most external TAs will work with an Acorn machine and most of them
emulate AT commands to appear like a modem.

I've used my TA with !TCPIP, Freenet, Arcterm7, Connector & the Ant Suite.

If you want to use X25 ie HDLC framing then most TAs define a simple
conversion to and from async.  You then connect your TA to your computer at
anything up to 460.8 kbits/s and away you go.  If you meant X25 over the D
channel then you can't do this yet over BTs network and I am betting that if
it ever becomes available it will be prohibitively expensive.

-- 
|- Nick Craig-Wood ---------------------------------- ncw@axis.demon.co.uk -|
|------- They say the dead will rise again.  And here they come now --------|