DZ(4)							     Kernel Interfaces Manual							     DZ(4)

NAME

       dz - DZ-11 communications multiplexer

SYNOPSIS

       /sys/conf/SYSTEM:
	    NDZ  dz_units  # 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 communica-
       tions multiplexer behaves as described in tty(4) and may be set to run at any of 16 speeds; see tty(4) for the encoding.

       Bit 0200 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 mknod /dev/tty02 c 2 130
       would cause line tty02 to be treated in this way.

       The dz 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 interrupts disabled.	It is not serious.

3rd Berkeley Distribution					 January 28, 1988							     DZ(4)