NetNews Usenet Archive 1992 #31/NN_1992_31.iso/spool/comp/dcom/modems/18703

Internet Message Format | 1992-12-30 | 16.3 KB

Path: sparky!uunet!stanford.edu!rutgers!cmcl2!panix!oppedahl
From: [e-mail] (Carl Oppedahl)
Newsgroups: comp.dcom.modems
Subject: Macronix 14.4KBPS modem - review
Message-ID: <[e-mail]>
Date: 30 Dec 92 19:50:13 GMT
Organization: PANIX Public Access Unix & Internet, NYC
Lines: 365


Review of Macronix 14.4 KBPS portable fax/data modem.  Comments
on US Robotics Worldport 9600 MNP modem.

I offer here, for benefit of usenet readers, these comments on
the Macronix 14.4 KBPS portable fax/data modem.  In summary, it
worked fine for data but I could not get it to work at all for
fax.  I also offer a few negative comments on the US Robotics
Worldport 9600 MNP modem.

Background

Some modem users, your scribe among them, will recall the days
when a 300-baud modem was the usual first purchase, and a
1200-baud modem was a big deal.  I recall reading articles
soberly concluding that at 1200 bits per second the theoretical
limit had been reached for data communication over a voice-grade
telephone line.  Nowadays everybody knows that very fast modems
have come way down in price.  A V.32bis modem carrying data at
14.4 KBPS, with data compression offering a theoretical maximum
data rate of 57.6 KBPS, and send/receive fax capability,
typically cost well over five hundred dollars just a year ago,
but can now be had for less than four hundred dollars.  The dust
has settled so that for a desktop system one can fearlessly
purchase an internal or external modem with all those
capabilities.  My personal favorites are the ZyXEL U-1496E for
MS-DOS machines, and the Global Village Teleport Gold for
Macintoshes, but of course there are many other modem choices
providing reliable service at good prices.

Finding a high-speed error-correcting modem you can trust for
portable use is, however, still a problem.  They cost a lot of
money and it is not easy to figure out which one to buy.  For
many years I used a Worldport 2496, with 2400-baud data and
9600-baud fax capability.  (Yes I know "baud" is strictly
speaking not synonymous with "bits per second".  Don't bother to
post or email corrections on this point.)  It was and is a
workhorse, having sent and received many, many millions of bits
and pixels over the years.  I seem to recall having paid $649 for
it several years ago.

But having gotten used to 14.4 KBPS at my desktop machines, I
realized I would not be happy with 2400 baud any more.  What's
more, I have come to rely on error correction.  I just don't like
being on a non-error-corrected connection any more.

I was about to go on a trip for which error correction and high
data rate would be important.  Time was of the essence so I went
to the store and picked out the only one in the store that seemed
close to what I wanted -- the US Robotics Worldport 9600 modem
with MNP.  With this modem I had to do without V.42 error
correction and V.42bis data compression.  There was no v.32bis
(14.4 KBPS) data rate, nor any fax send or receive capability.
It is small, the size of a pack of cigarettes.  It did not have a
light indicating that error correction was in place, nor lights
for transmitted or received data.  But it did what I needed for
one trip, calling to one destination.  More recently I had lots
of trouble with its MNP4 error correction handshaking ability.  I
sent it in for warranty service and when it came back it had all
the same MNP troubles.  Since then I have returned it to US
Robotics in the hopes that they will refund my $400 purchase
price.

So I went to a different store and looked for another modem.
This time I wanted 14.4 KBPS fax and data, and V.42 and V.42bis
protocols.  The only portable modem the new store had meeting
these requirements was a Macronix portable modem, on sale at
$290.

Now, it turns out to be no easy trick uniquely identifying the
Macronix model number of the modem I bought.  The box says the
modem has 14.4KBPS fax and 14.4KBPS data capability, with V.42
and MNP 4 error correction and V.42bis and MNP 5 data
compression.

It was also no easy trick reaching a level of confidence that the
modem in the box has capabilities matching those written on the
box.  The modem has an FCC ID of "FZV-Maxlite 96-144", which
suggests that the modem's fax speed is 9600 BPS and that the
modem's data speed is 14,400 BPS.  The modem's user manual says
the same thing.

For reference in case the reader wants to match things up with
his or her own Macronix modem, my modem serial number is
ML1441466.  My manual says "software release 1.20" and
"MAN-000010".  The Maxtalk software supplied with my modem was
version 1.30, and the Comit software supplied with it had version
number 1.68.  The modem firmware version obtained by typing ATI3
is "V1.270 TR14-Jxxx-001 007".

Shape and size

The modem is about the size of a pack of cigarettes, like the two
above-mentioned Worldports, if one ignores the rather bulky
serial cable and the AC adaptor.  It can use an AC adaptor or a
9-volt battery, but since the battery only lasts half an hour or
so, the AC adaptor is recommended.

The modem cable, about which more is said below, has an enormous
bulge next to the plug that fits the modem.  The bulge, which
presumably contains a ferrite bead to limit RF propagation down
the serial cable, is so large and heavy that I worry it would,
with time, weaken the modem's serial connector with its downward
force on the cable.  It makes the cable difficult to store when
traveling, since the whole cable is comparable in bulk to the
modem itself.  The AC adaptor is typical for small AC adaptors.
Because battery life is so short the traveler really has no
choice but to pack the modem itself, the bulky serial cable, and
the AC adaptor.  After a while one starts to wonder whether one
should just give up and carry a ZyXEL modem in the bag with the
laptop computer.

Status lights

In most external desktop modems there are lights to show
off-hook, carrier detect, and data rate status.  Some modems also
have lights to show whether error correction is working, the
status of handshake signals such as DTR, as well as the content
of the TD and RD lines and the auto-answer status.  Many fax/data
modems have a light telling whether the modem is carrying fax or
data information.  Most battery-powered modems have a "low
battery" warning light.  And with most modems the lights are
labeled.

The Macronix modem has two status LEDs, each of which is
variously off or red or green.  Regrettably the LEDs are
unlabeled on the modem and the user manual gives only cryptic and
contradictory explanations for to them.  After some trial and
error and correspondence with the manufacturer one gleans, more
or less, what the LEDs mean.  The left LED gives the power and
off-hook status:  red means the modem is powered and on-hook, and
green means the modem is powered and off-hook.  The right LED
conveys the data rate, albeit crudely -- if the light is on and
green the data rate is 4800 BPS or higher.  If the light blinks
and is red a call is being received.  Since the modem designers
didn't make any use, for example, of a red "on" light, some of
the potential information-carrying ability of the two-color LED
is wasted.  One wishes that the red "on" light could have been
programmed by the designer to mean "carrier detect", or "error
correction mode", or "fax in progress".  One wishes there could
have been a low battery warning light.

The hookswitch relay in the modem makes a very loud click when
going on-hook or off-hook, so the green LED indicative of
off-hook status is a bit redundant.  One wishes that LED had been
allocated to "carrier detect" or one of the other meanings
mentioned above.

The modem serial connector

Most modems use a female DB-type connector with either nine or 25
pins.  Apparently to save space, the Macronix uses uses a
nine-pin DIN connector, which means that ordinary serial cables
cannot be used with the Macronix.  One is stuck using the
supplied proprietary cable with a nine-pin DIN plug at one end
and a DB9 plug at the other.  The cable has to go wherever the
modem goes, and if it were ever misplaced or broken the modem
would be useless.  It does not give the user a warm fuzzy feeling
that the pin assignments on the DIN connector of the modem are
undocumented anywhere in the written materials supplied with the
modem.  One has the sinking feeling that two or three years down
the line the cable will wear out and one will have to buy a
replacement cable from the manufacturer at a dear price.  Lots of
competing modems (including he above-mentioned Worldports) use
standard serial cables that will presumably be available cheaply
for many years.

The documentation

After some time with the user manual it becomes clear that the
supplied manual is a "generic" manual, intended to apply to any
of several Macronix-brand fax/data modems running the Maxtalk
software, variously internal and external, with or without error
correction, and having any of a range of highest possible data
rates.  This helps to explain why the manual says nothing about
the serial cable pinouts, the LED status lights, battery
installation, and the like;  these are addressed in a two-page
pamphlet packed with the modem.  It also helps to explain why
from time the manual refers to the highest possible data rate
being 9600 BPS when the box and modem "connect" messages both
suggest it is 14.4 KBPS.

The installation procedure is spread among several places, mostly
the user manual and the two-page pamphlet.  It leads up to a
grand finale in which you "register your purchase" via modem.
Despite several diligent attempts on my part, I was never able to
figure out how to do it.  I could not even work out whether it
was supposed to be consummated by fax or by data connection,
although the documentation hinted it would take place via the
Macronix BBS.  I did manage to log onto the BBS, but none of the
BBS menus seemed to include a "registration of purchase"
procedure.

Customer Service

Perhaps I was just unlucky, trying to call for technical help
only a few days before the Christmas holidays.  I gather there is
only one technician answering questions on MS-DOS modems for
Macronix.  My first call to the technician was on December 21,
and by December 28 I had still not managed to get my first
questions answered.  A fax had supposedly been sent to me on
December 23 answering some of my questions, but I had not
received it, and despite several calls the fax could not be
resent to me.  As of December 28 the technician who had
supposedly sent the fax was said to be out and not expected back
for a few more days.  One would have thought that the fax he
supposedly sent could be found and resent, but no one at Macronix
could find it.

In my third call to Macronix I was connected with a fellow who
identified himself as the Macintosh specialist, who listened to
my tales of woe on being unable to send faxes.  He told me I
could not return the modem for warranty service until after
January 1 because the person in charge of RMA (returned
merchandise authorization) numbers would be out until the new
year.

All in all, I was not very satisfied with Macronix customer
service.  However, it was toll-free, and they accept faxes.
There is no way to get customer service via email nor via the
Macronix BBS.

The hardware

The modem, all by itself, is a full Hayes-compatible
V.32bis/V.42bis/MNP5 data modem.  I used it several times
connecting to various modems and it worked just fine for data
communications.

The modem is warm to the touch when operating.  I expect this is
largely due to the voltage regulator inside, and to a lesser
extent due to power dissipation in the rest of the electronics.

There is a monitor speaker.  When I used it, the volume of the
outgoing touch-tones was good, but the audio volume of the call
progress signals from the other end of the telephone line (e.g.
dial tone, ringing sound, vocal prompts) was poor.

The software

The Macronix comes with lots of software, called Maxtalk Comit,
and Winfax.  Maxtalk is a package of several dozen files used for
sending and receiving faxes.  Winfax, which I did not test, is
intended to integrate the fax capabilities of the modem into
Microsoft Windows.  Comit is a particularly clever and versatile
program which can be used to explore and test comm port and
interrupt assignments, and performs lots of handy system
diagnostics.  Comit can also add MNP protocols 2-5 and 7 in
software, a capability that is wasted with the Macronix since
error correction and data compression are both provided in
hardware.

Fax capability

I was unable to get the fax capability to work.  Using the
supplied Maxtalk software I tried to send a simple fax to each of
several fax machines.  it never worked, and I got a variety of
error messages.

Macintosh capability

Although I did not test it, I have the impression Macronix will
supply, at extra cost, a cable with plugs to fit the modem and a
Macintosh, together with fax and data communications software.

Error correction

The modem has both error correction and data compression in
hardware, and can provide them in your choice of flavors:  MNP or
CCITT V-series protocols.  The documentation provides precious
little background on how to turn the protocols on and off, and
unaccountably whenever you run Comit it seems to turn off the
V-series protocols in the modem hardware.

To get:        Set        And set
-------        ---        -------
V.42 EC        S48=7        S46=136
V.42bis DC    S48=7        S46=138
MNP4 EC        S48=128    S46=136
MNP5 DC        S48=128    S46=138

In addition to the above settings, to get error correction you
must have appropriate settings for quite a few registers
including the \N, %C, and %M registers.  Factory default settings
will work fine for those registers.

The factory default settings for the modem are such that the
"connect" message tells next to nothing about the type of
connection that your modem has established with the distant
modem.  But you can coax out much more by turning on all the bits
of S-register 95.  This gives a "connect" message with a
several-line report giving the modem-to-modem data rate, the type
of error correction (MNP or V.42) that has been negotiated, and
whether or not data compression has been negotiated.  The
contents of these "connect" reports are, however, a bit cryptic
and are nowhere explained in the modem documentation.  It turns
out that if the type of error correction negotiated by the modems
is V.42, the report communicates this by the phrase LAP-M.  It's
true, of course, that some users probably know that LAP-M means
v.42.  And it's true that the user manual has one brief mention
of the term LAP-M tucked away in an appendix which would permit
the diligent reader to glean that it means V.42.  But it would be
much better had the user manual provided a list of the possible
connection reports and their meanings.

The modem gives a "product capabilities" report if you type ATI4.
The report is:

a007050C08484402F
bC60000000
r16E5111151012000
r3000111170000000

I don't know what this means, and the the manual says nothing in
explanation.

The modem gives a signal quality report if you type AT%Q.  I was
unable to figure out how to interpret the numerical report.  It
is not clear which is better -- larger numbers or smaller.  This
is nowhere in the manual.

Documentation deficiencies

The manual is a bit sketchy on some of the S-register
programming.  For example, it says default register settings are
shown.  But the manual does not reveal the default values for
registers \K, \T, and %E, nor registers S44, S46, S49, S50, S82,
and S95.  The manual is wrong about the default value for the S25
register.

The AT&V command gives a report of register settings, and among
the registers whose values are reported are registers S44, S49,
and S50.  But nothing in the documentation says what those
registers do.

The AT&V command does not display the settings for the \T, %D,
%M, %S, S82 and S95 registers.  A number of other registers are
not displayed in any easy-to-read way, but are hidden in
S-registers, namely:

command    bits    register
-------    ----    --------
&P    7    S22
&L    2    S27
\A    5-6    S40
\G    7    S40
\K    2-4    S40
\L    2    S41
\N    0-1    S40
%C    0    S41
%E    1    S41

Conclusions

Not only did the modem fail to send faxes, but after a few days
the modem stopped working for data as well.  I returned the modem
to the store.  The modem did not work at all in fax mode, and the
other factors mentioned above make me think something better is
out there, or will be some day.

--
Carl Oppedahl AA2KW  (intellectual property lawyer)
30 Rockefeller Plaza
New York, NY  10112-0228
voice 212-408-2578     fax [phone]