DZ(4)                  OpenBSD Programmer's Manual (VAX)                 DZ(4)

NAME
     dz - DZ-11 multiplexer device interface

SYNOPSIS
     dz0 at uba0 csr 0160100 vector dzrint dzxint
     dz0 at vsbus0 csr 0x200a0000

DESCRIPTION
     A DZ-11 provides 4 or 8 communication lines with partial modem control,
     adequate for OpenBSD dialup use.

     An optional argument flags may be supplied with the device specification
     in the config file indicating that the line corresponding to bit number i
     is not properly connected, and should be treated as hard-wired with car-
     rier always present.  Thus specifying `flags 0x04' for dz0 would cause
     line tty02 to be treated in this way.

     Normal I/O control parameters for individual lines are managed by
     ioctl(2) calls.  Line speeds may be initiated via the ttys(5) file,
     stty(1) or ifconfig(8) to name a few, see tty(4).

     The dz driver monitors the rate of input on each board, and switches be-
     tween 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]    dialups

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.

SEE ALSO
     stty(1), tty(4), ttys(5), getty(8)

HISTORY
     A dz driver appeared in Version 32V AT&T UNIX.

OpenBSD 2.9                     March 27, 1991                               1
