Xref: utzoo comp.sys.ibm.pc.hardware:2467 comp.dcom.modems:7020
Path: utzoo!attcan!uunet!mcsun!ukc!stl!robobar!ronald
From: ronald@robobar.co.uk (Ronald S H Khoo)
Newsgroups: comp.sys.ibm.pc.hardware,comp.dcom.modems,uk.misc
Subject: Re: Wanted: Advise on a modem for my PC.
Message-ID: <1990Oct23.063532.21901@robobar.co.uk>
Date: 23 Oct 90 06:35:32 GMT
References: <6758@suns401.cel.co.uk>
Organization: Robobar Ltd., Perivale, Middx., ENGLAND.
Lines: 36

In article <6758@suns401.cel.co.uk> njm@cel.uucp () writes:

> I'm in the market for a modem capable of the following speeds / modulation /
> compression modes: v21, v22, v22bis, v32, v42, MNP 5.

Why MNP 5 ?  Or more to the point, why don't you specify V.42bis ?
Specifying  MNP 5 rather than V.42bis is probably a mistake.  Specifying
both might be reasonable if you absolutely need compatibility, though.

>  Are there similar but better modems available?

The one which comes to mind is the Hayes Ultra which *does* have V.42bis
as well.

>  Are there any very strong reasons for not getting an internal modem?

Yes.  Many.  They are a mistake.
1) it can be damn near impossible to debug difficult connexions without
   the blinkenlights
2) Their serial interface is builtin, so
	2a) You are at the mercy of whatever serial chips, etc they use,
	    and its compatibility with the software you're driving it with.
	2b) It's a "dumb" serial interface, so you lose significant amounts
	    of CPU power if you're driving it at the kind of speeds that
	    V.42bis over V.32 can give you.
	2c) It uses up a whole interrupt by itself which you will curse
	    when you come to want to add more peripherals to the PC.

2b is probably only important if you are multitasking, and together with
2c, only a disadvantage if you ever exercise the option of getting
an intelligent serial card, and I suppose that's normally only an option
for multiuser PC applications.  But 1) is VERY important.  Don't underestimate
it.

-- 
ronald@robobar.co.uk +44 81 991 1142 (O) +44 71 229 7741 (H)