fc.4

来自「<B>Digital的Unix操作系统VAX 4.2源码</B>」· 4 代码 · 共 104 行

.TH fc 4 VAX
.SH Name
fc \- VAXstation serial line interface
.SH Syntax
.B "device fc0 at ibus?  flags 0x0f vector fcxrint"
.SH Description
.NXS "fc interface" "VAXstation serial line interface"
.NXR "VAXstation serial line interface"
This serial line interface is similar to
the DZQ11 four-line communications multiplexer.
An 
.PN fc 
interface provides four communication ports with partial modem control
on port 2, adequate for dialup use.
Only port 2 supports modem control (dialup access),
all other ports must be operated as local lines.
Each line attached to the serial line controller
behaves as described in
.MS tty 4
and may be set to run at any of 16 speeds. 
For the encoding, see
.MS tty 4 .
However, configuration requirements dictate fixed speed
operation of ports connected to the console terminal and
graphics devices.
.PP
The 
.PN fc 
ports are configured as follows:
.PP
.nf
\fBPort\fR      \fBUsage\fR
.br
0         Graphics device keyboard at 9600 BPS
1         Mouse or tablet at 4800 BPS
2         Communications (with modem control)/local terminal
3         Serial printer port at 9600 BPS
.fi
.PP
A diagnostic console terminal
may be connected to port 3.
When the diagnostic console is in use,
the processor may be halted by pressing the BREAK key.
The selection of which port to use for the console
is made during the processor's power on sequence
and cannot be changed after power on.
If the Low End Graphics Subsystem (LEGSS) console is present,
it will be used;
otherwise the device connected to port 3 will be the console.
.PP
For the 
.PN fc 
device,
the flags should always be specified as ``flags 0x0f''
(all 4 lines hardwired).
The state of port 2 may be established by specifying either
modem or nomodem as part of the 
.PN /etc/ttys 
file entry for tty02;
see
.MS ttys 5 .
The default state of port 2 may be controlled by
flags bit 2.
Set ``flags 0x0f'' for a hardwired line,
``flags 0x0b'' for dialup operation (wait for carrier).
.PP
The 
.PN fc 
driver operates in interrupt-per-character mode
(all pending characters are flushed from the silo on each interrupt).
Silo alarm mode is used by the DZQ11 driver at times of high input
character traffic.  This mode is not used by the 
.PN fc 
driver,
due to the need to track mouse or tablet position changes
in real time.
.SH Restrictions
Speed must be set to 9600 BPS on the console port, 9600 BPS on
the keyboard port, and 
4800 BPS on the mouse port.
The fc driver enforces this restriction; 
that is, changing speeds with the stty command may
not always work on these ports.
.SH Diagnostics
fc0: input 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 will
then print a message on the console with interrupts disabled.
.SH Files
.nf
.DT
/dev/console	console terminal or graphics device
/dev/tty00	not used
/dev/tty01	local terminal - multiuser configuration only
/dev/tty02	dialup or local terminal
/dev/tty03	printer port or local terminal
/dev/mouse	mouse or tablet - workstation configuration only
/dev/fcscreen	console message window for workstations
.fi
.SH See Also
console(4), devio(4), tty(4), ttys(5), MAKEDEV(8)