DMF(4)                                                                  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 _d_m_f device provides 8 lines of asynchronous  serial  line  support.
       The  first  two of these have full modem control.  The device also pro‐
       vides a line printer port similar to the LP-11.  Other features of  the
       DMF-32  are  not supported.  During autoconfiguration, the driver exam‐
       ines the configuration of each DMF-32 and adjusts the interrupt vectors
       so that fewer vector locations are used if possible.

       Each line attached to a DMF-32 serial line port behaves as described in
       _t_t_y(4).  Input and output for each line may independently 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 _d_m_f to 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 _d_m_f0 would cause line ttyA2 to be treated in this way.
       Flags  should  be  set for all lines without hardware support for modem
       control.

       The serial line part of the _d_m_f 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 _d_m_f_n is designated by a minor device  number  of
       the  form  128+_n.   Columns  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
       _l_p(4) driver.

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

SEE ALSO
       tty(4)

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 seri‐
       ous.

       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 vec‐
       tors for a conflict with another device.

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.



4.2 Berkeley Distribution        May 16, 1986                           DMF(4)