v7 man page for du

DU(4)							     Kernel Interfaces Manual							     DU(4)

NAME
       du, dp - DU-11 201 data-phone interface

DESCRIPTION
       The dp0 file is a 201 data-phone interface.  Read and write calls to dp0 are limited to a maximum of 512 bytes.	Each write call is sent as
       a single record.  Seven bits from each byte are written along with an eighth odd parity bit.  The sync must be user  supplied.	Each  read
       call  returns  characters  received  from  a  single  record.  Seven bits are returned unaltered; the eighth bit is set if the byte was not
       received in odd parity.	A 10 second time out is set and a zero-byte record is returned if nothing is received in that time.

FILES
       /dev/dp0

SEE ALSO
       dn(4)

BUGS
       The name dp0 is a historical dreg.

																	     DU(4)