[comp.dcom.modems] supra 2400 baud modem

dale@vicorp.UUCP (Dale Nielsen) (03/21/89)

I'm interested in buying an external 2400 baud modem for use with
an Amiga 500.  I see ads for a Supra 2400 baud external modem for
$129.95 in magazines.  Does anyone out there have any experience
with this modem?  Is it reliable or is it cheap junk?

Any advice/recommendations with regard to this or other inexpensive
2400 baud modems would be appreciated.
-- 
	--Dale Nielsen				ARPA:  dale@vicorp.UU.NET
	  V. I. Corporation			UUCP:  uunet!vicorp!dale
	  Amherst Research Park			PHONE: (413) 253-3482
	  Amherst, Massachusetts  01002		FAX:   (413) 256-0574

hbo@nobbs.ucsb.edu (03/21/89)

In article <1896@vicorp.UUCP>, dale@vicorp.UUCP (Dale Nielsen) writes...

>I'm interested in buying an external 2400 baud modem for use with
>an Amiga 500.  I see ads for a Supra 2400 baud external modem for
>$129.95 in magazines.  Does anyone out there have any experience
>with this modem?  Is it reliable or is it cheap junk?

   I have had good luck with my Supra 2400, running it 24 hours a day, 7 days
a week on my BBS. It doesn't support error correction or anything, but it is
a good, basic Hayes compatible in a nice compact package. You can't beat it for
the money. I heard someone complain they couldn't connect to Supras. I think
they may have been running a Ven-Tel or Racal-Vadic. I forget which. I haven't
had any complaints on the Quirk (805-967-9357) though.

--
Howard Owen, Computer Systems Manager           internet: hbo@nobbs.ucsb.edu
Physics Computer Services                       BITNET: HBO@SBITP.BITNET
University of California, Santa Barbara         HEPNET/SPAN:   SBPHY::HBO
"I am not a pay TV service!"                    805-961-8366 (work)

chiesa@netcom.UUCP (15) (03/27/89)

In article <1896@vicorp.UUCP>, dale@vicorp.UUCP (Dale Nielsen) writes:
> ...  I see ads for a Supra 2400 baud external modem for
> $129.95 in magazines.  Does anyone out there have any experience
> with this modem?  Is it reliable or is it cheap junk?

I bought this very modem in December 1988 and am using it to compose this
message.  It is Hayes-compatible and all that, and does what it's supposed
to, by and large, but I feel as though it's more line-noise sensitive than,
say, the Atari SX212 (1200 baud) modem I was using previously.  I don't know
how much more line-noise-sensitivity to EXPECT at 2400 baud, but on Portal
for instance I occasionally get thousands and thousands of garbage charac-
ters, the source of which I have no clue to -- Portal, PC Pursuit (Telenet),
or the Modem...

I *DO* tend to lose data when reading text from local BBS systems at 2400,
so I only use it at 1200 on those systems; this was something of a disappoint-
ment when I first discovered it, but I've learned to live with it.  After
all, as above, I don't know whether the problem is MY modem, the BBS's modem,
the BBS software, my terminal software, etc. etc....  Portal works MUCH 
better at 2400 baud than do the local BBS's, so I'm inclined to blame the 
BBS software itself in that case...

usenet@cps3xx.UUCP (Usenet file owner) (03/28/89)

in article <40@netcom.UUCP>, chiesa@netcom.UUCP (15) says:
$ Summary: Bought one in December
$ 
$ In article <1896@vicorp.UUCP>, dale@vicorp.UUCP (Dale Nielsen) writes:
$$ ...  I see ads for a Supra 2400 baud external modem for
$$ $129.95 in magazines.  Does anyone out there have any experience
$$ with this modem?  Is it reliable or is it cheap junk?
$ 
$ I bought this very modem in December 1988 and am using it to compose this
$ message.  It is Hayes-compatible and all that, and does what it's supposed
$ to, by and large, but I feel as though it's more line-noise sensitive than,
$ say, the Atari SX212 (1200 baud) modem I was using previously.  I don't know
$ how much more line-noise-sensitivity to EXPECT at 2400 baud, but on Portal
$ for instance I occasionally get thousands and thousands of garbage charac-
$ ters, the source of which I have no clue to -- Portal, PC Pursuit (Telenet),
$ or the Modem...
$ 
$ I *DO* tend to lose data when reading text from local BBS systems at 2400,
$ so I only use it at 1200 on those systems; this was something of a disappoint-
$ ment when I first discovered it, but I've learned to live with it.  After
$ all, as above, I don't know whether the problem is MY modem, the BBS's modem,
$ the BBS software, my terminal software, etc. etc....  Portal works MUCH 
$ better at 2400 baud than do the local BBS's, so I'm inclined to blame the 
$ BBS software itself in that case...

I've had one for about two months now and use it intensively. I feel
that it is great for a personal use modem, but I doubt that I would use
it it a production setting (for that I recommend the MultiTech 224E).

I've used it over the same lines to the same places as I have a Hayes
2400 and don't see a significant amount of increase in sensitivity 
to line noise. It's also a sturdy little unit.

I paid something like $170 in a store for it. If you can mail order it
for $130, grab it.


John H. Lawitzke           UUCP: Work: ...rutgers!mailrus!frith!jhl
Dale Computer Corp., R&D               ...decvax!purdue!mailrus!frith!jhl
2367 Science Parkway                   ...uunet!frith!jhl
Okemos, MI, 48864                Home: ...uunet!frith!ipecac!jhl

bill@bilver.UUCP (bill vermillion) (04/02/89)

In article <40@netcom.UUCP> chiesa@netcom.UUCP (15) writes:
>In article <1896@vicorp.UUCP>, dale@vicorp.UUCP (Dale Nielsen) writes:
>> ...  I see ads for a Supra 2400 baud external modem for
>> $129.95 in magazines.  Does anyone out there have any experience
>> with this modem?  Is it reliable or is it cheap junk?
>
>I bought this very modem in December 1988 and am using it to compose this
>message.  It is Hayes-compatible and all that, and does what it's supposed
>to, by and large, but I feel as though it's more line-noise sensitive than,
>say, the Atari SX212 (1200 baud) modem I was using previously.  I don't know
>how much more line-noise-sensitivity to EXPECT at 2400 baud, but on Portal
>for instance I occasionally get thousands and thousands of garbage charac-
>ters, the source of which I have no clue to -- Portal, PC Pursuit (Telenet),
>or the Modem...

One of the things that cause one modem to cost more than another is how well
it can handle noise & how sensitive it is.   The problem of "thousands and
thousands of garbage characters" is most likely your modem switched speed.

What's that.  The 2400 BPS (not baud - a 2400 BPS modem actually runs at 600
baud) standard is v.22.bis.   The 1200 BPS standard in this country is called
212A.   Specifications call for the modem to "fall back" - that is reduce
speed if the line can't support the higher speed.

In a modem with a locked interface, typically one with buffering and MNP, or
modems like the trailblazers, you won't see this problem, if both modems are
of the same type, or IF the software handles speed change (which it almost
invariable does not).

What happens is you are merrily communicating at 2400bps, the line goes bad,
both modems fall back to 1200bps.  BUT - and here is the BIG problem.  Your
software stays at 2400.  When the modem dropped to 1200 so did the interface.
VOILA!  Garbage city.

Well how can we handle this.  Well we can't handle it very well.

Back in the days when there were basically two commonly used standards, 103a
for 300bps and 212a for 1200 you could look at pin 12 of the modem and find
out whether the modem was at 1200 or 300.  I used hardware connections on a
bbs system I ran years ago to look at that pin.  NEVER had to have a user type
CR's, breaks, etc.  If they called at 300 pin 12 was low so set the software
to 300 baud.  Pin 12 high - 1200 baud. (we talk 1200 BAUD from computer to
modem - but the modem talks 600 BAUD and 1200 BPS to the other modem).

Now when Hayes brought their 2400 unit to the market they changed the way pin
12 worked.  If pin 12 was high you were at 2400.  If it was low you were at
some other speed.  Other mfrs did implement additional pins to keep with the
orginal specs.  That is pin 12 high for 1200bps.  The additional pin went high
to indicate 2400.

But since this is not at all standard what is typically done is to look at the
software result codes from the modem and set the speed that way.

But it can't handle noise - the modem falls back and it is all over.

As to come BBSes being more susceptible to noise than others - the noise can
come on either side of the line (eg signal coming or going).  It could be
that the BBS sensitivity is low and your incoming characters are garbled and
echoed back.  Or it could be that their output is low and you are seeing
garbage on your side on what is good data.

The test of the latter is if you see garbage but the system responds normally
to your keystrokes the noise is on the return line.  If the system responds
erraticly the noise is on the incoming.

The best cure is a better modem.  The easiest, as you have found, is to reduce
speed.


>
>I *DO* tend to lose data when reading text from local BBS systems at 2400,
>so I only use it at 1200 on those systems; this was something of a disappoint-
>ment when I first discovered it, but I've learned to live with it.  After
>all, as above, I don't know whether the problem is MY modem, the BBS's modem,
>the BBS software, my terminal software, etc. etc....  Portal works MUCH 
>better at 2400 baud than do the local BBS's, so I'm inclined to blame the 
>BBS software itself in that case...


-- 
Bill Vermillion - UUCP: {uiucuxc,hoptoad,petsd}!peora!rtmvax!bilver!bill
                      : bill@bilver.UUCP