Getting Maximum Throughput 12-9
Possible dictionary sizes:
Your modem uses an 11-bit, or 2048-entry dictionary, but they can
reduce its size to accommodate a remote modem that uses a 9- or
10-bit dictionary.
■Maximum string length of each entry. As the dictionary fills, your
modem deletes the oldest unused strings.
V.4 2bis compression is more efficient than MNP5 compression, in part
because it dynamically deletes entries that are no longer used. In
addition, it works better with files that are already compressed. These
include.ZIP files and 8-bit binary files.
MNP5 compression should NOT be used with binary files because it adds
data to the files, which lessens throughput. (The a dditional data is
stripped when the file is decompressed by the remote modem.) When
transferring such files, it's best to set the modem to &K3 (See the
information in data compression). This allows V.42bis compression to
work dynamically with the compressed data, but disables MNP5.
Getting Maximum Throughput The following guidelines should help you to make the most of the
Business Modem's advanced performance features. In many instances,
experimentation and experience will indicate what works best for your
applications.
Maximum
throughput results
when:
■The communications software allows fixing the serial port rate higher
than the connection rate, by setting the software to 115200, 57600,
or 38400 bps and setting the Business Modem to &B1.
If the software automatically switches serial port rates to follow the
connection rate, the Business Modem's serial port rate must be also
set to follow the connection rate for each call, &B0, and throughput
will be limited.
Bits Entries
9512
10 1024
11 2048