30
Chapter 3 - Configuration
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 MT2834 is set to auto-reliable mode. In this mode the
MT2834 determines during the handshake whether the other modem is
using V.42 error correction. If it is, the MT2834 then switches itself to
reliable mode and enables error correction. If it is not, the MT2834 remains
in non-error correction mode.
Normally, we recommend that you leave the MT2834 set to auto-reliable
mode (&E1). However, you may encounter some circumstances in which
the MT2834 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