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) delim off