From: axa12@po.CWRU.Edu (Ashok Aiyar)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: Re: Modems(14.4) Supra vs. Boca vs. Zoom vs. Cardinal. Which one?
Date: 27 Sep 92 14:51:53 GMT
Article-I.D.: usenet.1a4hq9INNom5
Reply-To: axa12@po.CWRU.Edu (Ashok Aiyar)
Organization: Case Western Reserve University, Cleveland, OH (USA)
NNTP-Posting-Host: thor.ins.cwru.edu


In a previous article, ccy@po.CWRU.Edu (Cheung C. Yue) says:
>I too am interested in v32.bis modems, and PC Connection has the Zoom external
>modem advertised at $289.00.  I have had a Zoom 2400 modem for a few years and
>had no problems with it.  However, in reading over the review in PC Magazine
>(Mar 17, 1992) re: v32.bis modem, I found out the following:
>
>1.  At that time, not all v32.bis will work with each other.  The most 
>    trouble-free (i.e. connects every time at 14.4) was the one from AT & T
>    Does anybody know if that has changed since March?
>
>2.  A critical connection is the RS232 port.  I gather standard RS232 can
>    run at a max of only 38.4 Kbps, but more efficient use of the 14.4 modem
>    needs a serial port running at 57.6 Kbps.  Does anybody know if the
>    Zoom modem, or for that matter, whether the Cardinal modem will do that?
>    (I guess whether they provide drivers to work the serial ports at those
>     rates).
>
>3.  Anybody has telephone numbers for Zoom and/or Cardinal?
>

Having tested several V.32bis modems, here is my feeling on them.

a) All the cheap modems are all based on the Rockwell RC144AC chip
	(or a derivative of the Rockwell chip)
	These include:
	Supra, Boca, Zoom, Cardinal, Gateway 2000 Telepath,
	TwinComm, LightningCom ...........
b) These modems are generally good value for the money.  But individual
	quirks persist.  For more details about the SUPRA, contact
	Glenn Crocker at Smith Computing Lab, CWRU.  My comments
	below will mostly pertain to the Zoom VFX V.32bis fax/modem,
	which was one that I tested most extensively.

Both the Supra and the Zoom have trouble initiating a fall-forward
as specified in the V.32bis CCITT spec. as line quality improves.
Both modems do not send serial breaks - this may or may not be of
importance to you.  The modems do not reset themselves, but have to
be manually reset.  This may have been corrected in the latest ROM 
release for the Supra.  Zoom has not yet corrected this.  This is a
big problem if you want people to dial-in to your computer.

The Supra supports Caller-ID, the Zoom does not (Caller ID has not
yet been implemented by Ohio Bell in Cleveland).

Neither modem has any trouble connecting to the US Robotics
V.32bis Courier modems that INS has provided for the CWRU Terminal
Servers.

Sending and receiving faxes is fine with the Zoom - I did not have
the Supra long enough to test fax operation.

I have also had very similar experiences with the Gateway 2000 Telepath.

The Zoom has trouble connecting to Telebit T-3000 and Telebit WorldBlazer
modems.  The Supra and Gateway Telepath did not have this problem.

About the DTE speed (i.e bps rate between the modem and the serial
port).  This is not a function of any software "driver", but is a 
direct function of the type of UART that your serial port has.

If you plan on using DTE speeds upto 57,600 bps, replace your
existing UART (if it is socketed) with a 16550AFN UART that
provides a 16 byte FIFO buffer, and use communication software
that will make use of a 16550 UART.

The 8250 UART has no buffer, and the 16450 UART has a 1 byte FIFO
buffer.  Keep in mind that some early versions of the 16550 such
as the NS16550 and NS16550A had the 16 byte buffer, but due to an
incorrect hardware implementation, the buffer could not be enabled.

A new UART should run you about $15 - $20.

Also, DTE speeds of 57,600 bps may be of little utility to you
if you only transfer files that are already compressed.  Irrespective 
of setting the DTE at 38,400 or 57,600, a compressed file such as
a *.ZIP file or *.ARC file will transfer at about 1600 cps on
a *true* V.32bis connection.

Finally, the modem that I was most impressed with was the US Robotics
Sportster V.32bis fax/modem which runs about $320.  The modem has
performed perfectly in every test that I have thrown at it, and
has connected to every other V.32bis modem that I have tried to
connect to with no problem.

I am in the process of setting up several network services for
the Department of Biochemistry CWRU, including a POP3/SMTP mail server,
and a network printer.  If the department expands it's objectives 
to include providing a dial-in/dial-out fax/modem pool, my 
recommendation is going to be the US Robotics Sportster V.32bis.

Regards,

Ashok
-- 
                          Ashok Aiyar
   		       axa12@po.cwru.edu
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