ST(4)

NAME
st - Systech MTI-1650 terminal multiplexor driver

SYNOPSIS
device st0 at mbad? csr 0x200 maps 0 bin 4 intr 3

DESCRIPTION
An MTI-1650 provides 16 serial lines. Each line of the MTI-1650 is configurable to support a modem or a terminal.

Each line attached to the MTI-1650 terminal multiplexor behaves as described in tty(4). Input and output for each line may independently be set to run at any of the following speeds: B50, B75, B110, B134, B150, B300, B600, B1200, B1800, B2400, B4800, B9600, and B19200.

The hardware signals DTR and RTS are enabled when the line is opened and disabled when the line is closed. These signals may be changed via ioctl calls to the device driver and are not used in in automatic flow control. Break detection and generation are also supported. See tty(4) for the encoding scheme.

The initial baud rate and line state for all lines are defined by the “stspeed” and “stflags” variables in the binary configuration file, /sys/conf/conf_st.c. These values are usually overridden (e.g., by getty(8)) when a line is opened.

FLAGS
The “flags” value in a “device st” entry in the kernel configuration file is ignored.

AUTODIALER SUPPORT
For normal Systech operation, DCD must be active to allow the USART receiver to operate. A port can be specially wired to support an auto-dial modem (both dial-out and dial-in on the same line) without requiring the modem's DCD to be active. The special rewiring consists of the following steps.

1)  Disconnect pins 4 (RTS), 8 (DCD), 6 (DSR) from the modem to the Sequent system.

2)  Loop pin 4 (RTS) to pin 8 (DCD) on the backpanel board of the Sequent system.

3)  Connect pin 8 (DCD) from the modem to pin 6 (DSR) on the Sequent system.

The following table illustrates the specially-wired connection.

Sequent system |  | Terminal
(Male conn.) |  | (Female conn.)
Pin # |  | Pin #
2 | to | 2 | TxD driven by Sequent system
3 | to | 3 | RxD driven by Modem
5 | to | 5 | CTS driven by Modem
6 | to | 8 | DCD driven by Modem
7 | to | 7 | Signal Ground
20 | to | 20 | DTR driven by Sequent system
Pin 4 is looped back to Pin 8 on the Sequent system side.

Refer to ttyconfig(8) for information on how to set the software configuration to support Systech lines used for auto-dial modems. Refer to the Sequent System Installation Guide for a description of standard wiring for Sequent terminals and modems.

A high-to-low transition on the auto-dialer's DCD output is interpreted as a hangup signal.

FILES
/dev/tty[h-k][0-f] /sys/conf/conf_st.c

SEE ALSO
tty(4), ttyconfig(8)

DIAGNOSTICS
For a complete description of Systech MTI-1650 error codes, refer to the Systech MTI-850/1650B Multiple Terminal Interface Technical Manual or call your Sequent Service Representative.

BUGS
The DMA input capability of the terminal multiplexor board is not currently used by this device driver. This may result in excessive overrun errors under heavy load.