US Robotics COURIER Manual de usuario descargar pdf (Pagina 128)

U.S. Robotics I-modem Command Reference

Handshaking, Error Control, Data Compression, and Throughput • Page 11-19

¥ MNP5 compression is disabled for Þles that are already compressed and 8-bit binary

Þles that appear to the I-modem to be already compressed. Disable MNP5 compressing

by sending the I-modem &K3.

¥ The Þle transfer is not slowed down by a File

Transfer Protocol. Many non-text Þles

require a File Transfer Protocol, but the results vary.

Note For the best throughput on error-controlled connections with hardware ßow

control, we recommend the most current version of ZMODEM

For example, certain public domain File Transfer Protocols have the following effects:

Kermit Newer versions support packets up to 9K and a sliding window design to elimi-nate

turn-around delay. With earlier versions, how-ever, throughput may be severely

reduced due to short block lengths (possibly under 128 bytes) and acknowledg-ment

turn-around time.

XMODEM

Throughput may be reduced if your version uses short block lengths (128 bytes).

Some versions use larger blocks (1K blocks). Throughput is also reduced by over-

head (error-control protocol information).

YMODEM

There is an improvement over XMODEM due to larger block lengths (1K bytes), but

throughput is still reduced by the protocol's error control overhead.

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US Robotics COURIER Manual de usuario Pagina 128