User`s manual

U.S. Robotics I-modem Command Reference

Handshaking, Error Control, Data Compression, and Throughput • Page 11-8

¥ V.32terbo: 19.2 Kbps, with an additional USR device-to-USR device speed of 21.6

Kbps.

¥ V.32bis: 14.4 Kbps.

¥ V.32, V.22bis, etc.: 9600 bps and lower.

ASL (used in V.32terbo and V.32bis modes) is a technique that allows the I-modemÕs

receivers and transmitters to act independently of each other. One transceiver may slow

down and then speed up without affecting the data ßow on the other. The result is more

efÞcient line operation.

Note When answering using V.32terbo, I-modems shift their serial port rate up

to 38.4 Kbps (for 21.6 Kbps connections) if the calling V.32terbo device

dials in at 21.6 Kbps. The answering V.32terbo device then sends data to its

computer at 38.4 Kbps. V.32bis I-modems also shift their serial port rate to

19.2 Kbps to make 14.4 Kbps connections. If your computer does not sup-

port these higher serial port rates, disable V.32terbo and/or V.32bis. (See

A, Alphabetic Command Summary.)

Note While most modems on the market now use higher speeds, there may be a

problem in answering older, V.32 modems at 9600 bps. Use Register S28 to

modify the duration of the extra tones used in V.32 negotiations, in the rare