With Auto Answer; Flow Control Overview; Transmit Data Buffer Sizes; Received Data Buffer Size - US Robotics COURIER User Manual

COURIER HIGH SPEED MODEMS
With Auto Answer
When set to &M4 or &MS and a call comes in, the modem goes
off hook and responds to received error control signals. If the
modem doesn't receive those signals and is set to Normal/
ARQ mode (&M4), it answers the call in Normal mode (&MO). If
it doesn't receive the signals and is set to ARQ mode (&MS), it
hangs up.
FLOW CONTROL OVERVIEW
This feature controls the flow of data into and out of the
modem's Transmit and Receive data buffers. Due to variations
in computer and terminal equipment and in software require-
ments, the Courier is shipped with all flow control options
disabled.
Users at Hewlett Packard installations that use the ENQ/ ACK
protocol should note the HP settings, &13 and &14, described
under Received Data Softioare Control (&In).
NOTE: Flow control of data from the DTE to the modem is
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required under the circumstances described under Transmit Data -
Flow Control ( &Hn). Received Data flow control is not as critical
unless, for example, you are writing incoming files to disk on a
very slow computer. -
Transmit Data Buffer Sizes
The size of the Transmit data buffer depends on whether the
connection is under error control or not, as follows.
• ARQ connections: 3.2SK bytes.
• Non-ARQ connections: 1.SK bytes, allowing use of error
control file transfer protocols such as Xmodem and
Ymodem without flow control.
If bit 3 of Register SlS is turned on, the non-ARQ buffer size is
reduced to 128 bytes, for the convenience of some remote users
of slower modems. See S-Register Summary, SlS, in Appendix B.
Received Data Buffer Size
The size of this buffer remains constant at 2K bytes.
4-6 Interface Controls
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