From: jim@n5ial.mythical.com (Jim Graham)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: Internal 14.4K Modems 
Date: Wed, 16 Dec 92 18:36:21 GMT
Distribution: world
Organization: Me? Organized? Hah! :-)

In article <28560@oasys.dt.navy.mil> lewis@oasys.dt.navy.mil writes:
> In comp.sys.ibm.pc.hardware, mitch@nosc.mil (Ray Mitchell) writes:

>> I'm in the process of buying a 14.4K internal modem and need some
>> guidance.

> I bought a Zoom 14.4k external, from Price Club at $239, that was the
>                                      ^^^^^EAST COAST, WASH. D.C.
> best price I've found. I like the external alot better than my old internal
> 2400 because it's a LOT easier to take it to another machine if I had
> to. Which I have done once so far, though I never thought I would ever
> have to. The externals also have the added feature of the indicator
> lights on the front, which is good for trouble shooting.

I sent this bit via e-mail, but since I'm hitting some points in another
followup, I'll mention this again....  do not buy an internal modem.
buy an external modem.  there are lots and lots of reasons behind this,
many of which are stated in the above followup.

now for the real reason for this post....

> One thing about 14.4 connections though, they are not guaranteed.
> I've found that I've had little success in obtaining a reliable 14.4k
> connection (My phone line is situated in a very noisey electrical
> environment which makes anything above 9600 difficult)

your case is apparently rather severe --- from what I've seen, as long
as you stay out of hotel rooms, and you don't have an insanely long/bad
local loop, you can generally expect good, solid performance from
V.32bis at 14.4 kb.  (most comp.dcom.modems readers should know this
anyways, but for those who don't...  hotel rooms generally have about
the worst phone service anywhere in the country...except for a few
existing step switches.)

there's another possibility, too....  I haven't been reading all of the
posts on Zoom, Supra, etc., that flood this group these days, but I
seem to recall seeing several posts on other topics (e.g., which modem
should I buy, etc.) saying that the Zoom modems (trying to put this
nicely) had lots of problems and were basically crap.  I could be wrong
about this, so don't quote me here.....  there are several active
threads on this here, so you should be able to find more in those posts.

> This brings up a question to all of the hardware heads out there....
> 
> I've looked at my I/O card and don't see chip with the markings
>    "16450" which is the chip I have according to PCTOOLS diagnostics
> Nor have, I seen anything that says "UART" on it.

well obviously, the chip isn't likely to have UART stamped all over it.
that's what the part number is for.  :-)

have you looked for things like 8250, 8250A, etc.?  the 8250A is, if
memory serves, functionally equivalent to the 16450.  I could normally
verify this from the data sheets, but since I'm still in the process of
unpacking after my move, my NS data sheets are in a box in a storage
locker....  anyone else have their data sheets handy?

there is also, of course, the possibility that you've got a non-standard
UART (perhaps something like a multi-function chip) that just happens to
emulate a 16450.  these are often complete trash (no surprise there for
most folks here), so be careful.

there is also a version of most NS UARTS (again, sorry but I don't have
the data sheets handy at the moment) that has 2 UARTS on it, and these
obviously have a different part number.

> Now the question...
> 
> Would upgrading the UART (either by board or by chip), improve the
> chance of obtaining 14.4k connections? (upgrade 16450 to a 16550)

not at all.  remember, the UART deals with communications between the
local modem and the computer.  the UART has no control over the phone
line, the quality of the modem-to-modem connection, etc....  now, if
you're having trouble with your computer not being able to keep up with
incoming data from the modem, that's another story.

questions?  feel free to e-mail me or post here.  I may not read other
groups too carefully, but comp.dcom.modems, comp.dcom.telecom, and
comp.text.tex are at the top of the list as far as reading news goes....
   --jim

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