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SERIES II INTELLIGENT DATA/FAX MODEMS
The command to disable compression is AT &E14 <CR>. If you have
an older UART or if you use your modem mostly for downloading long,
compressed files from BBSs, you may want to include the &E14
command in your initialization string as follows:
AT &F S0=0 X4 &E14 ^M
As a general rule, you should try to transmit files in already-compressed
form rather than relying on V.42bis hardware compression. Because
software compression is more efficient than hardware compression, you
will have a higher throughput with the former. Of course, this efficiency
does not include the time spent compressing and decompressing .ZIP
or .SIT files, but it will save on phone bills. And hardware compression
will still be there for those occasions when it is inconvenient to
compress a file with software. Note also that when you download files
with compression disabled, you can use a slower serial port if you have
an older UART.
3.7.1 Disabling Error Correction
By default, the Series II Modem is set to auto-reliable mode. In this
mode the Modem determines during the handshake whether the other
modem is using V.42 error correction. If it is, the Modem then switches
itself to reliable mode and enables error correction. If it is not, the
Modem remains in non-error correction mode.
Normally, we recommend that you leave the Modem set to auto-reliable
mode (&E1). However, you may encounter some circumstances in
which the Modem will work better with error correction turned off. For
example, it has been reported that on CompuServe error correction will
slow file transfers at modem speeds of 9600 bps and under. If this is a
problem for you, you can turn off error correction with the command
AT &E0, or you can include the command in your initialization string as
follows:
AT &F S0=0 X4 &E0 ^M