scc - Serial keyboard/mouse/communications interface
controller scc0 at tc0 slot 3 vector sccintr
Two base board Zilog scc dual UARTS provide DEC 3000
series personal systems with keyboard, mouse, and serial
communications interfaces. The serial communications
interfaces can operate at baud rates from B50 to B57600
(see tty(7)).
The driver for the scc interface supports hardware flow
control using the Request to Send (RTS) and Clear to Send
(CTS) signals. When hardware flow control is enabled, the
flow of input data is controlled by the RTS signal and the
flow of output data is controlled by the CTS signal. If
the CTS signal is off, the driver will suspend output to
that line until the CTS lead is reasserted. Likewise, the
driver will turn off the RTS lead to tell the device connected
to the line to stop sending data as a result of
congestion on the host side. When the condition clears,
the driver will turn on the RTS lead to tell the device to
resume sending data.
In alternate console configurations (that is, no graphics
head), communications port 2 (/dev/tty01) becomes the system
console. The serial system console port always operates
at 9600 BPS, 8-bits, no parity. No modem or hardware
flow control is supported.
Data communications equipment attached to the console
serial port in alternate console configurations must be
set to 9600 BPS, 8-bits, no parity. The scc driver
enforces this restriction.
Only communications port 1 (/dev/tty00) includes full
modem control.
console terminal local terminal local terminal
console(7), devio(7), modem(7), tty(7), MAKEDEV(8)
scc(7)
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