🚀 go-pugleaf

In article <1992Oct15.165257.7343@cs.odu.edu> imbri_m@aesc.cs.odu.edu (Mark Imbriaco) writes:
>Why wouldn't you consider a modem without v.42bis?  I have a GVC v.42 with 
>the port locked at 19.2k and I ran it side by side with a v.42bis modem 

Well, you were transfering a pre-compressed file if you noticed no difference
V.42 and V.42bis have little to do with each other (at least in as-much as
what they are designed to accomplish...)

V.42 is error correction, it cant compress *AT ALL*.  V.42bis provides (at
least in theory) 4:1 data compression (this is why you lock your port at
4X higher than your actual connect speed). 

If you noticed no difference in transfer speed, the file you were sending
was already compressed, nullifying V.42bis's effect.

>noticing little or no difference.  MNP functions almost as well, and if you

Heee Heee Heee Hee.... Someone pick me up, I think I just coughed up a lung.

Saying MNP performs as well as V.42bis is somewhat like saying a yugo functions
almost as well as a Porche 911.

>are doing file xfers you would want it turned off for better performance 
>anyway.. right?

Nope.   V.42bis is smarter than MNP.  When MNP transfers a pre-compressed
file it tries to compress it anyway, and the overhead can actually slow
your transfer somewhat.  V.42bis tries to compress it and says "Oh, I cant
compress this anymore than it already is," and turns itself off (coming
back into play once the transmitted data IS compressable).

I didnt see the previous posts in this thread (the poster wanted to upgrade
his modem from V.32 to V.42).  Im sure someone along the way tackled that
on already, but just in case here goes.

V.32 is a CCITT signalling protocol for transmission at 9600BPS.  V.42 is
a CCITT error correction protocol..  As you see, you cant upgrade from
one to the other since they are not dependant on one another (sort of like
saying you want to upgrade your V8 to a steering wheel.  They are both
part of a car, but not a function of the other...)

Scott
-- 
Go FAST!            |  Internet:  wilken@plains.nodak.edu   |     AMA #587126 
Take Chances!       |     UUCP: ..!uunet!plains!wilken      |     DoD #0087 
VF700F Interceptor  |        Bitnet:  WILKEN@PLAINS         |