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

NAME
     dmf - DMF-32 terminal multiplexor

SYNOPSIS
     device dmf0 at uba? csr 0160340 vector dmfsrint dmfsxint dmfdaint
           dmfdbint dmfrint dmfxint dmflint

DESCRIPTION
     The dmf device provides 8 lines of asynchronous serial line support.  The
     first two of these have full modem control.  The device also provides a
     line printer port similar to the LP-11. Other features of the DMF-32 are
     not supported.  During autoconfiguration, the driver examines the config-
     uration of each DMF-32 and adjusts the interrupt vectors so that fewer
     vector locations are used if possible.

     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 dmf0 would cause
     line ttyA2 to be treated in this way.  Flags should be set for all lines
     without hardware support for modem control.

     Normal I/O control parameters for individual lines are managed by
     ioctl(2) calls.  Line speeds may be initiated via getty(8) and stty(1) or
     may be communicated by other programs which utilize ioctl such as
     ifcongif(8), see tty(4).

     The serial line part of the dmf driver normally enables the input silos
     with a short timeout (30 milliseconds); this allows multiple characters
     to be received per interrupt during periods of high-speed input.

     A line printer port on a dmf is designated by a minor device number of
     the form 128+n. See MAKEDEV(8). Column and lines per page may be changed
     from the default 132 columns and 66 lines by encoding the number of
     columns in bits 8-15 of flags and the number of lines in bits 16-23.
     This device does not provide the fancy output canonicalization features
     of the lp(4) driver.

FILES
     /dev/tty[A-CE-I][0-7]
     /dev/ttyd[0-7]
     /dev/lp

DIAGNOSTICS
     dmf%d: NXM line %d.  No response from UNIBUS on a DMA transfer within a
     timeout period.  This is often followed by a UNIBUS adapter error.  This
     occurs most frequently when the UNIBUS is heavily loaded and when devices
     which hog the bus (such as RK07s) are present.  It is not serious.

     dmf%d: silo overflow.  The 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.

     dmfsrint, dmfsxint, dmfdaint, dmfdbint.  One of the unsupported parts of
     the dmf interrupted; something is amiss, check your interrupt vectors for
     a conflict with another device.

SEE ALSO
     tty(4)

HISTORY
     The dmf driver appeared in 4.2BSD.

BUGS
     It should be possible to set the silo timeout with a configuration file
     option, as the value is a trade-off between efficiency and response time
     for flow control and character echo.

OpenBSD 2.9                     March 27, 1991                               2
