DZ(4)                                                                    DZ(4)



NAME
       dz - DZ-11 communications multiplexer

SYNOPSIS
       device dz0 at uba0 csr 0160100 vector dzrint dzxint

DESCRIPTION
       A  DZ11 provides 8 communication lines with partial modem control, ade‐
       quate for UNIX dialup use.  Each line attached to the  DZ11  communica‐
       tions  multiplexer behaves as described in _t_t_y(4) and may be set to run
       at any of 16 speeds; see _t_t_y(4) for the encoding.

       Bit _i of flags may be specified for a dz to say  that  a  line  is  not
       properly  connected,  and that the line should be treated as hard-wired
       with carrier always present.  Thus specifying  ‘‘flags  0x04’’  in  the
       specification  of dz0 would cause line tty02 to be treated in this way.

       The _d_z driver monitors the rate of input on each  board,  and  switches
       between  the  use  of  character-at-a-time  interrupts and input silos.
       While the silo is enabled  during  periods  of  high-speed  input,  the
       driver polls for input 30 times per second.

FILES
       /dev/tty[0-9][0-9]
       /dev/ttyd[0-9a-f]        dialups

SEE ALSO
       tty(4)

DIAGNOSTICS
       dz%d:  silo overflow.  The 64 character input silo overflowed before it
       could be serviced.  This can happen if a hard error occurs when the CPU
       is running with elevated priority, as the system will then print a mes‐
       sage on the console with interrupts disabled.  It is not serious.



4th Berkeley Distribution        May 16, 1986                            DZ(4)