long@sh.cs.net (Daniel Long) (03/07/87)
To quote Microcom glossies:
Class 4:
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Two new techniques found in our new Class 4 modems result in increased
throughput over current MNP Class 3 modems.
First, Adaptive Packet Assembly constantly monitors phone line conditions for
noise and interference. It then automatically adjusts data packet size,
continually optimizing the packet size relative to the number of
retransmissions caused by noisy lines. This process is totally transparent to
the user.
Second, as part of our continuing refinement of MNP, Microcom software
engineers have further optimized data throughput by minimizing protocol
overhead.
These two new techniques result in 10-15% increased throughput over current
Class 3 Modems.
Class 4 Modems include the AX/1200 and AX/2400 modems.
Class 5:
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MNP Class 5 products include the AX/2400c modem.
Microcom Class 5 products come with all of the advantages of Class 4 modems
plus a new compression technique that encodes data, effectively allowing it
to be transmitted at speeds in excess of 4800bps.
Of course, when not in compression mode, the AX/2400c is compatible with 2400
and 1200 bps modems.
Class 6:
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MNP Class 6 products include the AX/9612c and AX/9624c modems.
These products have everything Class 4 and 5 have plus two new advantages that
result in significantly greater throughput and maximum flexibility.
Statistical Duplexing (TM) allows Class 6 modems to adjust line bandwidth and
data traffic flow automatically to achieve maximum throughput. Not only are
these modems the first to perform at 9600bps over normal dial lines, they can
also reach error-free transmissions speeds as high as 19,200bps.
Universal Link Negotiation (TM) permits Class 6 modems to connect with most
popular dial-up modems -- and then negotiate up or down to the highest mutually
acceptable speed. This gives MNP Class 6 modems maximum compatibility and
flexibility, which achieving the greatest possible data transfer speed.
MNP Availability (from Microcom Distributer News, Volume II, 12/84)
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"Vendors may license the protocol for a one-time fee of $2500."
(I think this was at a time when only up to Class 3 was available).
For more info about MNP, write:
-------------------------------
Microcom, Inc.
1400A Providence Highway
Norwood, MA 02062
(617) 762-9310
(My only connection with Microcom is that we've used their modems.)
Hope this helps,
Dan Long
CSNET