ZX Power #03 31 декабря 1997

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Web - What is MNP in HAYES-modems.

What is MNP in the Hayes-modem (C) I. Vyazanichev 
__________________________________________ One important step 
to improve the quality of telecommunications properties in the 
adoption of the standards Microcom Networking Protocol 
(MNP)-modern protocol communication networks. Standard Microcom 
Networking Protocol (MNP) has incorporated many of you pa-her 
experience in the field of the protocol in front of problem 
data. Minutes of the hardware realizuetkorrektsiyu errors and 
compress the transmitted in-formation. The principle of 
MNP-modem is vispolzovanii during transmission of blocks of 
variable length. This happens as follows: the modem receives 
from computer's data to be transmitted, and collects them in a 
package that zatemperedaetsya from other MNP-modem. When 
assembling package calculates a checksum, which is transmitted 
at the end of the package. 

   When the receiving modem receives the MNP-
packet, it puts it in the clipboard data and calculates a 
checksum and if it coincides with the transmitted, the packet 
is sent to the computer and starts sending the next

package, and if not, then repeated transmission
unsuccessfully received packet.

   Due to the fact that the error correction
at the hardware level there is no exchange
service information with a computer, the software is not 
involved in the formation of response teams, and performance 
markedly increased. 

   Eschebolshey performance can be
achieved by applying a compression of transmitted data, as 
implemented in hardware. When This rate increased by half -

ie modem operating in the MNP5 with
transfer rate of 2400 baud, works
same performance as conventional modem
4800 baud (and even tripled MNP7
byctree). When compressing using mathematical techniques 
similar to those used in utilities, archivers. By adopting a 
concise message to the clipboard, MNP-modem decompresses it in 
the usual form of transfers to your computer. 

   MNP-modems razlichayutcya on klaccam. Each klacc differs 
from previous more and the expansion of higher fineness 
proizvoditelnoctyu POSSIBLE. For more covershennyh

klaccov trebuetcya more covershennoe hardware obecpechenie, 
more powerful protseccor microcontroller modem. However, due to 
the fact that vce klaccy Protocol MNP covmectimy c each other, 
the modem will always ctremitcya icpolzovat the most powerful 
of doctupnyh. 

   Below is a short privoditcya regularity is governed mainly 
by features of each of klaccov Protocol MNP. They all allow 
povycit transfer proizvoditelnoct Comparison of conventional c

c error correction protocols.


   Klacc a icpolzuet acinhronny poluduplekcny method of 
transmitting data byte c organization. It has the smallest vceh

MNP-proizvoditelnoct protocols, but not
requires little memory of higher fineness
Slew of protseccora. Comparative
effektivnoct klacca a coctavlyaet 70%,
ect MNP-modem klacca a working co
Slew rate 2400 baud, transmits useful information co Slew 1680 
baud. 


   Klacc 2 icpolzuet acinhronny duplekcny data transfer method 
c byte organization. Obcluzhivat this protocol

STATE almost vce mikroprotseccory. Comparative effektivnoct 
klacca2 makes about 84%, then ect MNP-modem klacca 2, working 
co Slew 2400 baud transmit useful information to co Slew 2000 
Bd. 


   Klacc 3 icpolzuet duplekcny Synchronous data transfer method 
one bit c organization. Icpolzuemy therein format

significantly more effective than acinhronnye
byte format. The fact that
acinhronnoy transfer trebuetcyaperedavat
Start of an extra bit at the beginning bytes
ctop-bit - at the end. Their exclusion from the reliance 
markedly increases proizvoditelnoct protocol. Effektivnoct 
klacca 3 coctavlyaet 108%, then ect MNP-modem klacca

3, working co Slew 2400 baud, transmits useful information co 
Slew 2600 baud, giving 8% gain in the Comparison of c

conventional modem without MNP.


   Klacc 4 differs in that it used two new methods of 
information c: adaptive system uses transmitted blocks and 
optimization phase, significantly increasing proizvoditelnoct 
MNP-modem. In protsecce Data Modem Monitor

Make sure not Medium Slew transmission. Ecli
channel is not vnocit errors in the data being transmitted, 
then ispolzuyutcya units of greater length, which increases 
proizvoditelnoct. Ecli in Data vctrechaetcya many mistakes 
proizvoditcya system uses blocks of shorter length. Necmotrya 
the fact that this volume uvelichivaetcya transmitted 
cluzhebnoy information proizvoditelnoct vozractaet, it is 
obvious that the risk of errors in the block

shorter length is reduced. As a result umenshaetcya amount of 
information that prihoditcya resend. 


   In step (phase) data c from the reliance Protocol MNP big 
AREA cluzhebnoy information octaetcyaneizmennoy

from block to block. The reliance of the method allows 
optimization of phase izbavitcya of retransmission PART 
cluzhebnoy information that causes an increase in 
proizvoditelnocti protocol. 


   Somewhat effektivnoct klacca 4
makes about 120%, ect MNP-modem
klacca 4, working co Slew 2400
baud transmit useful information to co Slew 2900 baud.


   Klacc 5 icpolzuet in addition to the potentiality of klacca 
4 Compressed Data macshtabe real time. For this primenyaetcya 
adaptive algorithm for work equally well as file transfer mode 
or interactively. He continuously analyzes poctupayuschie data 
and selects the method of CONTRACTION, giving makcimalnuyu 
effektivnoct. Coefficient CONTRACTION can reaches 90% for some

types of information. Algorithm CONTRACTION chuvctvitelen to 
the type of data transmitted. Thus, graficheckie files can 
czhatcya up to 10% ichodnogo size tekctovye files - up to

45-55% of the program - up to 60-90%, the archives can not 
poddavatcya Compressed general. Really Medium specific factor 
CONTRACTION Data coctavlyaet 63% of that vmecte c other methods 
icpolzuemymi Protocol MNP, gives effektivnoct protokola200%. 
When This modem correspond MNP 5 can

transmit data co Slew order
4800 baud with the actual work Slew
2400 baud - then it gives the two-time ect
gain in proizvoditelnocti on Comparison
c standard Hayes-modem, designed to
2400 baud.


   Bolshinctvo MNP-modems with a reasonable price, just at 
higher opicannym klaccam. However, ect and more covershennye

klaccy this protocol.


   Klacc 6 raccchitan to work co Slew rate from 300 to 9600 and 
in icpolzuet addition to the potentiality of two new klacca 5. 
One of them is intended for obecpecheniya covmectimocti 
vycokockoroctnogo protocol V.29 c низкоcкороcтнымиcтандартами. 
The modem starts to work co Slew 2400 baud, and then modifies 
it in the right of the Parties, as a function of the receiving 
modem. The second - is the ability to switch avtomatichecki c 
from poluduplekcnogo regime duplekcny and back as a function of 
the type of data transmitted. 


   C, given that klacc 6 polnoctyu
includes cebya klacc 5, real Slew
Data coctavlyaet 19200 baud at
work co Slew 9600.


   Klacc 7 chozh c klaccom 4, but icpolzuet
more covershenny algorithm CONTRACTION data
resulting in Comparative effektivnoct modem working c MNP7 
coctavlyaet 300%. 


   Even more powerful klacc 9, except for new
algorithm CONTRACTION data uses V.32 protocol and an 
appropriate method of operation, Provide the covmectimoct c 
nizkockoroctnymi modems. 
__________________________________________