Path: utzoo!attcan!uunet!cs.utexas.edu!sun-barr!rutgers!att!alberta!ubc-cs!eric!handel!durham
From: durham@handel.mpr.ca (Paul Durham)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Looking for a Sync/Async modem for PC/XT
Summary: Internal modems
Keywords: Synchronous modem
Message-ID: <1688@eric.mpr.ca>
Date: 23 Jun 89 20:03:13 GMT
References: <64114@yale-celray.yale.UUCP> <595@pegasus.ATT.COM>
Sender: news@eric.mpr.ca
Reply-To: durham@handel.UUCP (Paul Durham)
Organization: Microtel Pacific Research Ltd., Burnaby, B.C., Canada
Lines: 27

In article <595@pegasus.ATT.COM> psrc@pegasus.ATT.COM (Paul S. R. Chisholm) writes:
>In article <64114@yale-celray.yale.UUCP>, jacquemin-michel@CS.YALE.EDU (Michel Jacquemin) writes:
>> I am looking for any information about synchronous 2400bps modems
>> for a PC/XT compatible.  I would use it to connect to an IBM
>> mainframe (using the BSC3780 bisynchronous protocol).

>> Being able to do async 2400bps (V.22 bis) as well would be a plus.

>> Internal preferred.

>. . . but this won't happen.  I'm pretty sure that internal modems have
>the equivalent of both an async adapter and a modem (except for the
>power supply).  

The Hayes 2400B internal modem handles both sync and async ( as does
the external version ). It handles this by doing an internal sync to
async conversion and moving the data through the 8250 UART ( I am 
not making this up ). You need a special driver called the Hayes
Synchronous Driver or some such thing.

There are also firms who sell a sync modem on a card with an 8251 USART
or whatever the PC uses for BSC communications, in fact I think you can
get a complete package with board and 3780 emulator. Try the ads in PC
magazine.


P. Durham