DZ(4)		    UNIX Programmer's Manual		    DZ(4)



NAME
     dz - DZ-11 communications multiplexer

SYNOPSIS
     /sys/conf/SYSTEM:
	  NDZ  _d_z__u_n_i_t_s  # DZ11; NDZ is in units of boards (8 each)

     /etc/dtab:
	  #Name Unit# Addr   Vector Br Handler(s)      # Comments
	  dz	?     160100 310    5  dzrint  dzdma   # dz11 terminal mux

     major device number:
	  raw: 2
     minor device encoding:
	  bits 0007 specify line on DZ unit
	  bits 0170 specify DZ unit
	  bit  0200 specifies non-blocking open (``CD always on'')

DESCRIPTION
     A DZ11 provides 8 communication lines with partial modem
     control, adequate for UNIX dialup use.  Each line attached
     to the DZ11 communications 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 _0_2_0_0 of the minor device number for DZ lines may be set
     to say that a line is not properly connected, and that the
     line should be treated as hard-wired with carrier always
     present.  Thus creating the special character device node
     "2, 130" via _m_k_n_o_d /_d_e_v/_t_t_y_0_2 _c _2 _1_3_0 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
     /dev/MAKEDEV	 script to create special files
     /dev/MAKEDEV.local  script to localize special files

SEE ALSO
     tty(4), dtab(5), autoconfig(8)

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 message on the console with



Printed 11/26/99	January 28, 1988			1






DZ(4)		    UNIX Programmer's Manual		    DZ(4)



     interrupts disabled.  It is not serious.






















































Printed 11/26/99	January 28, 1988			2