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SI(4)		       FreeBSD Kernel Interfaces Manual			 SI(4)

     si	-- driver for Specialix	International SI/XIO or	SX intelligent serial

     device si

     For ISA host cards	put the	following lines	in /boot/device.hints:"isa""0xd0000""12"

     The si driver will	be removed in FreeBSD 12.0.

     The Specialix SI/XIO and SX hardware makes	up an 8	to 32 port RS-232
     serial multiplexor.

     The system	uses two components: a "Host adapter", which is	plugged	into
     an	ISA, EISA or PCI slot and provides intelligence	and buffering/process-
     ing capabilities, as well as an external bus in the form of a 37 pin

     On	this cable, "modules" are connected.  The "SI" module comes in a 4 and
     8 port version.  The "XIO"	and "SX" modules come only in 8	port versions.

     The host adapter polls and	transfers data between the modules and the
     rest of the machine.  The Host adapter provides a 256 byte	transmit and
     256 byte receive FIFO for each of the 32 ports that it can	maintain.

     The XIO modules can operate each of their 8 ports at 115,200 baud.	 The
     SI	version	can run	at 57,600 baud.	 The SX	modules	can operate each of
     their 8 ports at up to 921,600 baud.

     SX	modules	are only supported when	connected to an	SX host	card.  SI or
     XIO modules are supported on any host card.

     The host adapter uses a shared memory block in the	traditional ISA	bus
     "hole" between 0xA0000 and	0xEFFFF.  The adapter can be configured	out-
     side range, but requires the memory range to be explicitly	non-cached.
     The driver	does not yet support this mode of operation.

     SX	ISA Host cards have an 8/16 bit	mode switch or jumper on them.	This
     switch or jumper MUST be set for 8	bit mode.

     The ISA adapters can use Irq's 11,	12 or 15 (and 9	and 10 in the case of
     SX	host cards).

     The si device driver may have some	of its configuration settings changed
     at	run-time with the sicontrol(8) utility.

     The si device driver also responds	to the comcontrol(8) utility for con-
     figuring drain-on-close timeouts.

     The driver	also defines 3 sysctl variables	that can be manipulated:
     machdep.si_debug sets the debug level for the whole driver.  It depends
     on	the driver being compiled with SI_DEBUG.  machdep.si_pollrate sets how
     often per second the driver polls for lost	interrupts.
     machdep.si_realpoll sets whether or not the card will treat the poll
     intervals as if they were interrupts.

     An	open on	a /dev device node controlled by the si	driver obeys the same
     semantics as the sio(4) driver.  It fully supports	the usual semantics of
     the cua ports, and	the "initial termios" and "locked termios" settings.
     In	summary, an open on a tty port will block until	DCD is raised, unless
     O_NONBLOCK	is specified.  CLOCAL is honored.  An open on a	cua port will
     always succeed, but DCD transitions will be honored after DCD rises for
     the first time.

     Up	to four	SI/XIO host cards may be controlled by the si driver.  Due to
     the lack of available interrupts, only 3 ISA SI/XIO host cards can	be
     used at once.

     The lowest	5 bits of the minor device number are used to select the port
     number on the module cluster.  The	next 2 bits select which of 4 host
     adapter cards.  This allows a maximum of 128 ports	on this	driver.

     Bit 7 is used to differentiate a tty/dialin port (bit 7=0)	and a
     cua/callout port (bit 7=1).

     Bit 8 through 15 (on FreeBSD) are unavailable as they are a shadow	of the
     major device number.

     If	bit 16 is a 1, the device node is referring to the "initial state"
     device.  This "initial state" is used to prime the	termios(4) settings of
     the device	when it	is initially opened.  If bit 17	is a 1,	the device
     node is referring to the "locked state" device.  The "locked state" is
     used to prevent the termios(4) settings from being	changed.

     To	manipulate the initial/locked settings,	the stty(1) command is useful.
     When setting the "locked" variables, enabling the mode on the lock	device
     will lock the termios mode, while disabling the mode will unlock it.

     /dev/si_control  global driver control file for sicontrol(8)
     /dev/ttyA*	      terminal/dialin ports
     /dev/cuaA*	      dialout ports
     /dev/ttyiA*      initial termios state devices
     /dev/ttylA*      locked termios state devices
     /dev/cuaiA*      initial termios state devices for	dialout	ports
     /dev/cualA*      locked termios state devices for dialout ports

     stty(1), sio(4), termios(4), tty(4), comcontrol(8), sicontrol(8)

     This driver is loosely based on driver code originating at	Specialix,
     which was ported to run on	BSDI by	Andy Rutter <>.
     The System	V driver source	is/was available by ftp	from

     This driver is not	supported by Specialix International.

     Peter Wemm	<> obtained	the code from Andy Rutter and
     ported it to FreeBSD and threw the	man page together.  Bruce Evans
     <> provided	a large	amount of assistance during porting.
     Nick Sayer	<> wrote the EISA, PCI and SX	portions.

     The interrupt tuning rate is not believed to be optimal at	this time for
     maximum efficiency.

     Polled mode (a feature of standard	Specialix drivers) is not implemented,
     but it can	be approximated	by turning on machdep.si_realpoll.  The	poll
     frequency is set by machdep.si_pollrate (in units of 1/100th of a sec-

     The driver	does not yet support baud rates	higher than 115,200 on SX mod-

     Operation outside the traditional ISA "hole" is not yet supported,
     although it should	work if	the test is removed from the probe routine.

     Multiple host cards are supported although	combinations of	hosts on dif-
     ferent bus	types have not been tested - device numbering is known to be a
     problem and may lead to unexpected	results.

FreeBSD	11.1			 July 8, 2017			  FreeBSD 11.1


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