Xref: utzoo alt.fax:596 comp.dcom.modems:5466 comp.unix.xenix:10587
Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!uunet!mtndew!friedl
From: friedl@mtndew.UUCP (Steve Friedl)
Newsgroups: alt.fax,comp.dcom.modems,comp.unix.xenix
Subject: Re: Fax H/W and Software for SCO-Unix/Xenix
Summary: character generators are A Big Win
Message-ID: <372@mtndew.UUCP>
Date: 14 Mar 90 17:30:50 GMT
References: <1990Mar7.144230.8576@tapa.uucp> <2000@ursa-major.SPDCC.COM> <1990Mar9.174642.3992@pcrat.uucp>
Followup-To: alt.fax
Organization: Steve's Barnburner 386
Lines: 48

Rick Richardson writes:
> The Fujitsu dexNET-200 is a serial interface device with some nice
> features such as "EIA/TIA-578 Service Class 2" style (just style,
> since there is no standard, yet) session management using "AT" commands,
> and Epson printer emulation (good for DOS folks, I don't think its a
> big win for UNIX types).

I can add quite a bit to the discussion on the Fujitsu; we use
this in our Interfax product (we call it the sx-200).  Please
keep in mind that I'm definitely on the technical side of the
house but you never know if some of the marketing BS has rubbed
off on me.   --shudder--

This modem does use AT commands for the Hayes emulation in
2400bps mode, but for the fax part they use control-code
sequences that resemble nothing else.

Epson emulation has been working out well for us, and it makes it
easy to build a driver for (say) WordPerfect under UNIX.  It is
certainly not as nice as HPLJ, but a Z80 can only do so much :-).

> Note that to send
> 9600 (synchronous) bps FAX you need to be able to deliver 12000 bps
> asynchronous to the modem.  This implies operating the interface
> at 19.2kbps.  For some computers, the additional implication is
> that the serial port be an intelligent one.

Rick is right about part of this: when sending image data, there
are indeed quite onerous bandwidth requirements to the modem
(12000bps looks about right).  Serial I/O cards with puny
256-byte buffers make this (ahem) a challenge.

For text-only applications, however, the modem's character
generator kicks in to do ASCII to G3 conversion, and this is a
*phenomenal* reduction in bandwidth.  The modem has a 16kbyte
buffer (or so), and it doesn't initiate the call until it has
filled.  Most of *my* outbound faxes fit into the buffer
completely so even a 2400bps interface would have been plenty.

     Steve

P.S. - I do contract Interfax work but I *do not* speak for V-Systems.

-- 
Stephen J. Friedl, KA8CMY / Software Consultant / Tustin, CA / 3B2-kind-of-guy
+1 714 544 6561 voice   /   friedl@vsi.com   /   {uunet,attmail}!mtndew!friedl

"How could anybody look at Miss April and *not* believe in a God?" - me