-=> Quoting Robert Osborne to Rick Collins/All <=-
-=> FidoMail to 1:163/215, please.-=<
RO> @MSGID: 1:346/49.0 33a18416
RO> Hi Rick,                           June 13, 1997
rc> RC>In spite of what you read here, most modems for sale today are
rc> easier RC>to configure and "set up" than were modems of the
rc> past. Most have RC>standard factory defaults so the init string
rc> need be no more than RC>AT&F or AT&F1. Most internals continue
rc> to have jumpers to select the RC>comm port and IRQ, even if they
rc> also support "plug and play". 
ro> What about externals? How are they configured for comm port and
ro> IRQ. I see several used modems for sale, both internal and
ro> external. Most do not have documentation with them as to how to
ro> configure. I 
You don't have to configure the external modem at all - you just have
to make sure the computer has a comm port properly configured, and
you plug into that.  Most PCs support two comm ports, Com1 and Com2. 
If you presently have an internal modem on Com2, when you remove it
you will have to enable the Com2 port in the PC (it would have to be
disabled to allow the internal modem to work on Com2).  So, with an
external modem you have to configure the port, not the modem.
ro> have seen some BBS software that is suppose to be able to tell
ro> you what comm port and Irq you are currently set to? Have you
ro> ever used any of this to try to set up a strange modem? My
ro> current 2400 baud modem 
If you're running a recent version of DOS, try typing MSD at the DOS
prompt.  That will run the MS Diagnostics.  Select Comm Ports from
the menu and the available ports will be displayed.  Note MSD will
treat your internal modem as a comm port.
ro> came with three jumper banks, two for comm port selection and the
ro> other for irq. It had a sheet of paper with it that told what
ro> each of the jumper combinations in pairs did - ie. COM1 
ro> J17-J13, J15-J16 - IRQ4 J4-J9 
That's still common.  Most plug-and-play internal modems can be
manually configured using jumpers, and usually that will work better
than relying on Windows to properly configure the modem.  If you buy
a plug-and-play internal, make _sure_ you can manually configure it
if necessary.
ro> on my Zenith 286AT. Then I tried one of the same internal
ro> modems on my 386 with windows! What a frustating learning
ro> experience that was! Even though I had a MS Windows book, I
ro> worked for about a week on and off trying to get the software in
ro> windows to accept the modem. I finally had to take it to a shop
ro> in town to get them to use their version of Windows disks to get
ro> the proper file so that it would accept the modem. This
ro> experience makes me almost totally want to purchase an external!
ro> Even if I do configure the internal by jumpers I still run the
ro> risk that the Windows SW won't reconfigure its files to the new
ro> modem right? 
The problem was most likely the need to _disable_ the PC com port to
permit Windows to "see" the modem.  You can't have two devices (the
internal modem _and_ the com port) sharing the same address and IRQ -
not and expect Windows to work properly, that is. :-)
Win 3.1 and WFWG had no "special" files to handle modems.  Win95 does
- it has a "modem.inf" file, but all that really does is ensure the
modem has the proper init string and is operated at the proper port
speed.  A new modem should come with a Win95 .INF file if the
"standard" .INF files distributed with Win95 are not suitable.
If you have an internal 2400 bps modem running on your system now,
you should be able to replace it with a new internal modem simply by
changing the jumpers on the new modem to match the configuration of
the old.  If you are using Win 3.1 or WFWG, that's all you have to
do.  If you're running Win95, after plugging the modem in you simply
have to run the Install program, and, if your modem is properly
configured (the jumpers) it will install and work without a problem.
ro> Are all UART chips clearly marked with the 16550 or 8250
ro> designation? Or do you have to go look for a manufacture's
ro> specific code for his chip? If it is an external modem, do you
ro> have to buy a special serial board to handle the extra speed of
ro> the 16550? 
Chances are you won't see an 8250 (they're old), but the 16550 is a
standard part, and they are a direct replacement for an 8250 or a
16450.  No special card required.
ro> While we are talking about speed, I see that there is a lot of
ro> traffic on the board about setting the speed of their modem. I
ro> though that the newer modems, 14.4 and above could all auto
ro> adjust to what ever speed the answering modem first transmitted
ro> at, if they could attain that speed. Other wise they shifted to
ro> a common lower speed? How does this work? Do you have to
ro> software set your speed to some upper limit? 
The modem is generally configured to connect at its fastest speed,
and it negotiates the speed with the remote modem.  That's almost
completely out of your control, and not your concern.  You simply
make sure your port speed is set _higher_ than the modem's maximum
speed:  either 57,600 or 115,200 bps for a 28,800 bps modem.
ro> I also thought that there is some limiting speed over the
ro> communication media being used. Ie 28.8 was the upper limit for
ro> telephone lines? Maybe higher for cable lines or fiber optic. 
ro> Is it also not true that the newer modems don't really transmit
ro> at higher rates, but instead compress and decompress the data on
ro> the fly to obtain faster rates of data thru put? When did they
ro> start all this and at what modem speed did compression take
ro> place? 
My telephone lines allow me connections consistently at 33,600 bps,
but your mileage may vary. :-)  The newer modems have both error
correction and data compression, and both of these _add_ to the
connect speed. The modem _does_ communicate at 33,600 bps, but your
throughput can be higher than that because of error correction and
data compression.  _That's_ why you use a port speed higher than the
modem speed.
ro> There is also some specifications that deal with error correction
ro> and being able to recognize compressed data? 
All automatic, and handled by the modems themselves.
ro> I would also like to know any thing you can provide me with on
ro> the subject of faxing via computer. Does the modem have
ro> anything to do with the faxing capability or is this all just
ro> software that you buy and install on the computer? I see modems
ro> listed as 2400 baud data and 9600 baud fax or something like
ro> that? I also see them listed with voice mail and other things i
ro> know nothing about but would possibly like to use. 
A modem that can handle faxes supports various "classes", the common
ones being Class 1, Class 2, and Class 2.0.  These last two are _not_
the same.  You just have to make sure that your fax software supports
the same class as the modem - and just about all software supports
Class 1.
ro> Would you please elaborate some on any of these subjects. Or
ro> suggest where I might obtain referernce information that
ro> discusses this in detail. I would like to better understand 
ro> the various modems that are out there and what is coming in the
ro> future before i make a decision on purchasing one. Do you work
ro> for one of the modem companies? Thank you for answering my
ro> request for help! 
I have no experience with any of the "voice" modems.  Personal
opinion is they're not yet ready for "prime time", and I'd need a
pretty convincing argument to consider any of them at this point.
No, I don't work for a modem manufacturer.  I'm just a user, like
you. :-)
TTFN. Rick.
Ottawa, ON 15 Jun 23:57 
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