SUMMARY
The MODE command cannot change the parallel port identified by PRN. At
boot time, PRN is internally configured by MS-DOS to direct any
communication with the PRN device to LPT1. In other words, PRN cannot
be configured to communicate with any parallel port other than LPT1
using MS-DOS commands. For instance, the following command is
sometimes mistaken as being able to associate a given parallel port
with PRN:
MODE LPTn
The letter "n" specifies the parallel device number of 1, 2, or 3. The
above command merely cancels redirection from a parallel port to a COM
port.
There are various public domain utilities that switch the address
specifications for LPT1 and LPT2, giving the impression that PRN is
communicating with another parallel device.