USRobotics V.34 - Manual (Page 113)

COURIER HIGH SPEED MODEMS
Summaries and Tables B-19
Register Default Function
S15 0 Bit-mapped register. To set the register,
see the instructions for S13.
Bit Value Result
0 1 Disable the modem's extra
high-frequency equalization if
it causes problems on shorter-
link calls
 HST-modems only
1 2 Disable online fallback
2 4 Disable 450 bps back channel 
HST only
3 8 Reset non-ARQ mode
Transmit buffer from 1.5K
bytes to 128*
4 16 Disable MNP Level 4; retrans-
mitting the larger Level 4 data
blocks may be a problem if you
expect a great number of
errors during a call
5 32 Set backspace key to delete
6 64 Some earlier 2400 bps MNP
modems, not made by U.S.
Robotics or Microcom, were
not fully compatible with the
MNP protocol. If you have
difficulty making a successful
2400 bps MNP connection with
a remote MNP modem, it may
be because of this incompati-
bility. Set S15 to 64 and try
again to make the connection.
7 128 Custom applications only
* The default 1.5K byte non-ARQ buffer allows data transfer
with X- and Ymodem-type file transfer protocols without using
flow control.
The 128-byte option allows remote users with slower modems
to stop data you're transmitting from scrolling off their screens.
When remote users send your computer an XOFF ()
and you stop transmitting, the data in transit from your
modem's buffer doesn't exceed the size of their screen.