3Com 56K Command Reference Manual page 143

Register Default Function
4
5
6
7
S16 0 Bit-mapped register. (See the beginning of this appendix for
information about setting bit-mapped registers). For
testing, see Chapter 15, Testing.
Bit
1
2
3
S18 0 Test timer for software-initiated loopback testing (&Tn);
disabled when S18 is set to 0. Used to set the duration of
testing, in seconds, before the Business Modem
automatically times out and terminates the test.
A complete list of S-Registers
16 Disable MNP Level 4; retransmitting
the larger Level 4 data blocks may
be a problem if you expect a great
number of errors during a call.
32 Set Backspace key to delete.
64 Some earlier 2400 bps MNP
modems, not made by 3Com 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
incompatibility. Set S15 to 64 and
try again to make the connection.
128 Custom applications only.
The default 1.5K byte non-ARQ
buffer allows data transfer with X-
and Y-modem type File Transfer
Protocols without using flow
control.
The 128-byte option allows remote
users with slower modems to stop
your transmitted data from scrolling
off their screens. When remote
users send your computer an XOFF
(<Ctrl-S>) and you stop
transmitting, the data in transit
doesn't exceed the size of their
screen.
Value Result
2 Dial Test
4 Test pattern.
8 Remote digital loopback.
A-7