A.9. Boot loaders are vulnerable to line noise
Most boot loaders will sit at their prompt forever after
receiving a single character of line noise.
Some modems will let the RS-232 signals
"float", sending noise when there is no caller. Because the modem
is not asserting Data Carrier Detect it expects the receiver to
discard the noise characters.
The combination of an unfortunate boot loader with an
unfortunate modem can result in a machine that will regularly hang
during booting.
If you cannot configure your boot loader to obey
DCD then be careful to test any modem you intend
to purchase to ensure that it does not generate characters when
their is no caller. At the present only
SYSLINUX implements full
RS-232 status signals.