duart - on-board serial ports
Each IRIS-4D system uses a DUART to connect the mouse and the keyboard.
Most models are also equipped with some number of additional `on-board'
serial ports. The Indigo, Indy, Indigo2, O2 and OCTANE have two ports;
and the Onyx and the Challenge can be configured with as few as four
serial ports and as many as 16. The first of these ports, /dev/ttyd1, is
often used for the `serial' or `debugging' console. Other ports are
commonly used for serial terminal connections, modems, a dial-and-button
box, or a bit-pad.
The Indigo, Indy and Indigo2 have only DIN-8 connectors. Onyx and
Challenge systems with a single IO4 board have 3 RS232 DB-9 ports, 2
DIN-8 powered peripheral ports, and 1 RS422 DB-9 port. Each additional
IO4 board provides three more RS232 DB-9 ports. All other systems have
DB-9 connectors for all ports. See serial(7) for the pinout on the
Special files for the serial ports exist in the /dev directory. These
files, tty[dfm][1-4] are created by MAKEDEV(1M). The Challenge and the
Onyx systems differ from previous systems in that all of their DUARTS
reside on the IO4 boards rather than on the processor boards. The ports
on the master IO4 board are numbered tty[dfm][1-4]. TTY 4 is an RS422
port, and it provides differential signal lines as part of this protocol.
If multiple IO4 boards are installed on an Onyx or Challenge system,
these ports will tty[dfm]45-56. The second IO4 provides ports 45-47, the
third IO4 provides ports 48-50, etc.
Each line may be independently set to run at any of several speeds, as
high as 19,200 or even 38,400 bps. Various character echoing and
interpreting parameters can also be set. See stty(1) and termio(7) for
By opening either the ttyd*, ttym*, or ttyf* device name of a port,
different hardware signals are supported. Ttyd* is typically used for
direct connect devices such as terminals; ttym* is used for devices that
use modem control such as modems; and ttyf* is used for devices that
understand hardware flow control such printers and high speed modems.
See serial(7) for detailed information on supported signals.
The driver for this device must be configured in the kernel by specifying
it with `INCLUDE' in the /var/sysgen/system file.
stty(1), serial(7), termio(7), keyboard(7), cdsio(7), system(4)
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