Date: Mon, 10 Feb 97 0:27:45 +0000 From: Andrew.Gordon@net-tel.co.uk To: smp@csn.net Cc: hardware@FreeBSD.ORG, multimedia@FreeBSD.ORG Subject: Re(2): isdn cards Message-ID: <"be7-970210002711-4D07*/G=Andrew/S=Gordon/O=NET-TEL Computer Systems Ltd/PRMD=NET-TEL/ADMD=Gold 400/C=GB/"@MHS> In-Reply-To: <199702092254.PAA27689@clem.systemsix.com>
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> I previously said: > > I know there are currently no drivers available for North American ISDN > > systems, but several people have proposed working on such a beast. > >I have a chance to pick up a couple cheaply and am wondering whether > > I have just been kicking around the idea of using the motorola isdn > bitsurfr pro ISA (ie, the internal card as oppossed to the external > device) as one would the external device. Specifically the box says > is uses an internal 16550 with the standard AT command set. So given > that I have already setup a PPP connection on FreeBSD with kernel PPP > and an external bitsurfr, wouldn't it also be possible to do the same > with the ISA card version (although I suspect I would have no access to > the fancy SOHO features till a true driver was written)? > Has anyone tried this? Are you sure that the internal bitsurfr is actually any different to the external (in the sense that an internal modem is no different to an external one). On the one hand, if it really does emulate a 16550 faithfully, it will work straight away but give you all the limitations of an external TA; on the other hand, if it doesn't you will be straight into writing a device driver for undocumented hardware before you even get started. Looking at: http://www.mot.com/MIMS/ISG/Products/bitsurfr_pc/app-notes.html it suggests you are right about the 16550 - though it's PnP with the associated inconvenience - but gives no hint that it can do any more than be an external TA, emphasising its "modem like" character. Doing PPP this way (ie. encode once as async PPP then decode/re-encode as sync PPP in the TA) will inevitably give some additional latency compared to driving a real piece of hardware more directly. So, IMHO, if you want a quick getaway stick with the external TA (avoiding the PnP aggro), but if you are talking of a real development project, why not leverage the work that has been done for Euro-ISDN and go for one of the cards already supported under FreeBSD by the BISDN package? The hardware reverse-engineering has already been done, so the remaining work is to implement whichever D channel protocol your teleco has implemented. The two main cards supported by BISDN are the Teles BRI/16.3 and the AVM A1. Teles certainly sell a USA-specific card "BRI/U", which is just the 16.3 with an on-board NT1 ("U" interface to "S" interface convertor - with Euro-ISDN, the Teleco provides the NT1). Details are at the Teles USA web site http://teles.winterlan.net/ (their 'home' site is http://www.teles.de/). AVM (http://www.avm.de) also apparently do a USA version of their A1 card, as their web page offers drivers for it, but I can't find any more details. The Teles and AVM cards are almost identical, giving you raw access to the B and D channels (with HDLC being done by the card where needed, and with deeper FIFOs than a 16550) and so letting you do anything that the line itself can do (voice calls, two simultaneous calls to different destinations etc. which are hard to do with an interface that thinks its a modem). For more info about the hardware, see http://www.arg1.demon.co.uk/avm.html
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