Fax H/W and Software for SCO-Unix/Xenix
Steve Friedl
friedl at mtndew.UUCP
Thu Mar 15 03:30:50 AEST 1990
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 at vsi.com / {uunet,attmail}!mtndew!friedl
"How could anybody look at Miss April and *not* believe in a God?" - me
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