User`s manual

U.S. Robotics I-modem Command Reference
Handshaking, Error Control, Data Compression, and Throughput • Page 11-20
The protocols listed above further reduce throughput when an error control connection is
established. The accuracy of the data is checked both by the File Transfer Protocol and
the I-modem. To avoid redun-dancy, use the above protocols only for non-ARQ connec-
tions, and only at speeds of 2400 bps and below.
Overhead is minimal with ZMODEM
, resulting in throughput that is almost equal to that
obtained with no File Transfer Protocol. ZMODEM should also be used for non ARQ
connections. Leave the I-modem at its &M4 and &K1 settings for both error control and
data com-pression.
YMODEM
-G is another good choice, but never use it unless both the local and remote
devices are using error control: if YMODEM-G detects an error, it aborts the transfer.
Do not use either pr
otocol with software ßow control (XON/XOFF signaling).