dzq.4

<B>Digital的Unix操作系统VAX 4.2源码</B>

.\" SCCSID: @(#)dzq.4	8.1	9/11/90
.TH dzq 4 VAX
.SH Name
dzq \- DZQ11 communications interface
.SH Syntax
.B "device dz0 at uba0 csr 0160100 flags 0x????"
.br
.ti +0.5i
.B "vector dzrint dzxint"
.SH Description
.NXS "dzq keyword" "DZQ11 communications interface"
.NXS "dz interface" "DZQ11 communications interface"
.NXR "DZQ11 communications interface"
A DZQ11 provides four communication lines with partial modem control,
adequate for dialup use.
Each line attached to the DZQ11 communications interface
behaves as described in
.MS tty 4
and can be set to run at any of 16 speeds.
See
.MS tty 4
for the encoding.
.PP
Bit
.I i
of 
.PN flags 
can be specified for a 
.PN dzq
to say that a line is not properly
connected, and that the line should be
treated as hardwired, with carrier
always present.
Thus, specifying ``flags 0x04'' in the specification of 
.PN dzq0
would cause line 2 to be treated in this way.
.PP
The 
.PN dzq
driver normally uses its input silos
and polls for input at each clock tick (10 milliseconds),
rather than taking an interrupt on each input character.
.SH Diagnostics
.PP
.B "dz%d: silo overflow"
.br
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 
then prints a message on the console with interrupts disabled.
.SH Files
.PN /dev/tty??
.TP 15
.PN /dev/ttyd?
(modem lines only)
.SH See Also
tty(4), MAKEDEV(8)