dmb.4

<B>Digital的Unix操作系统VAX 4.2源码</B>

.\" SCCSID: @(#)dmb.4	2.4	8/19/87
.TH dmb 4
.SH Name
dmb \- DMB32 communications multiplexor
.SH Syntax
.B "device dmb0 at vaxbi? node? flags 0x????"
.br
.ti +0.5i
.B "vector dmbsint dmbaint dmblint"
.SH Description
.NXR "DMB32 communications interface"
.NXA "DMB32 communications interface" "DMB32 serial printer interface"
.NXS "dmb interface" "DMB32 communications interface"
A
DMB32
device provides eight asynchronous communication lines with modem control.
The device driver also supports a connection to a line printer
through the line printer port of the
DMB32.
.PP
Each line attached to a
DMB32
serial line port behaves as described
in
.MS tty 4 .
Input and output for each line may independently be set to run at any
of 16 speeds.  See
.MS tty 4
for the encoding.
.PP
Bit
.I i
of flags can be specified for a
.PN dmb
to say that a line 
should be treated as a hardwired connection, with carrier always present.
If bit
.I i
of flags is not set, the line operates under full modem control.
Modem lines will operate in accordance to the CD (carrier detect),
DSR (data set ready) and CTS (clear to send) leads.
Thus, specifying ``flags 0x0004'' in the specification of
.PN dmb0
would cause line 2 on the DMB32 to be treated as hardwired,
with carrier always present.
In this example, the remainder of the lines will be modem control lines.
.SH Restrictions
The DMB32
provides a synchronous port, but this is
not supported by the driver.
.SH Diagnostics
.B "dmbinit: async lines unavailable"
.br 
This message is produced at system boot time, if the DMB32
fails its internal self test, indicating that the asynchronous lines have
failed to configure.
.PP
.B "dmbinit: printer port unavailable"
.br 
This message is produced at system boot time, if the DMB32
fails its internal self test, indicating that the printer port
failed to configure.
.PP
.B "dmb%d: fifo overflow"
.br 
The character input fifo overflowed
before it could be serviced.  This can happen if the CPU is running
with elevated priority for too long a period of time.
Overflow errors can
indicate that configuration constraints have been reached.
.PP
.B "dmb%d: DMA Error. tbuf = 0x%x"
.br 
A DMA output transfer failed.  This can be caused by a memory error
or an invalid pte (page table entry).
For a description of the error code in the
``tbuf'' register, see the DMB32 documentation.
.PP
.B "dmb%d: DMB Hardware Error. TX.DMA.START failed"
.br 
The 
.PN dmb 
failed to clear the start bit.  Normally, this is cleared to signal
that a DMA transfer has completed.
.PP
.B "dmb%d: Modem Error. tbuf = 0x%x"
.br 
Indicates a problem with a modem or its cable.
For a description of the error code in the
``tbuf'' register, see the DMB32 documentation.
.PP
.B "dmb%d: Internal Error. tbuf = 0x%x"
.br 
Indicates that the DMB32 detected an internal error.
For a description of the error code in the
``tbuf'' register, see the DMB32 documentation.
.PP
.B "hfBdmb%d: uio move error"
.br 
An error occurred when copying a printer buffer from user space
to system space.
.PP
.B "dmbsint"
.br 
The unsupported synchronous port of the DMB32 interrupted because
of a problem.  Check your interrupt vectors for a conflict with
another device.
.SH Files
.PN /dev/tty??
.TP 15
.PN /dev/ttyd?
(modem lines only)
.SH See Also
tty(4), MAKEDEV(8), dmbsp(4)