TTY(4spp" " " ")    RISC/os Reference Manual     TTY(4spp" " " ")



NAME
     tty - Signetics 2681 uart driver or sable uart emulation
          driver

SYNOPSIS
     Signetics 2681 configuration entry:
     {
          "tty",         s2681init,    s2681open,
          s2681strategy, nulldev,     s2681ioctl,
          DTTYPECHAR|DTTYPECONS,
          DTFSNONE,     "console uart"
     }

     Sable uart emulation configuration entry:
     {
          "tty",         sconsinit,    sconsopen,
          sconsstrategy, nulldev,     sconsioctl,
          DTTYPECHAR|DTTYPECONS,
          DTFSNONE,     "console uart"
     }

DESCRIPTION
     Tty refers to the either the Signetics 2681 uart driver or
     the sable uart emulation driver.  The 2681 driver is used
     when the standalone library is built for use on actual
     hardware, the sable emulation driver is used when the stan-
     dalone library is built for use with sable.

     The 2681 driver currently handles only uart 0 on the R2300
     CPU board.  Controller 0 refers to uart port A, controller 1
     refers to uart port B.  The baud rate for uart port A is
     determined by the PROM monitor environment variable $lbaud;
     the baud rate for uart port B is determined by the PROM mon-
     itor environment variable $rbaud.  The following baud rates
     are recognized: 75, 110, 134, 150, 300, 600, 1200, 1800,
     2400, 4800, 9600, and 19200.  If no baud rate or an illegal
     baud rate is set, port A will be set to 9600 baud, port B
     will be set to 1200 baud.  For all baud rates, 8 bits of
     data with no parity are transmitted, parity is not checked
     on received data.  For all baud rates except 110, 1 stop bit
     is transmitted; for 110 baud 2 stop bits are transmitted.
     If either port A or port B receives a break that port will
     cycle between the following baud rates: 110, 300, 1200,
     2400, 4800, 9600, and 19200.

     The sable uart emulation driver provides a console interface
     while operating with the sable simulator.  See sable(1spp)
     for more details.

REGISTERS
     On the R2300 CPU board the 2681 control registers are based
     at physical address 0x1e008002; each byte-wide control



                         Printed 1/6/92                    Page 1

TTY(4spp" " " ")    RISC/os Reference Manual     TTY(4spp" " " ")



     register has 3 pad bytes associated with it.  See the R2300
     CPU Board Product Description for more details.

IOCTLS
     The 2681 driver supports the following ioctls:

   ioctl(fd, FIOCSCAN, 0)
     Scan the uart for pending input; if found, move the input to
     tty input buffer, process any special characters (see
     intro(1spp) and intro(3spp)).

   ioctl(fd, TIOCRAW, flag)
     If flag is non-zero, disable processing of special charac-
     ters Control-Z and Control-D.  If flag is zero, enable pro-
     cessing of special characters Control-Z and Control-D.  Note
     that special character processing of Control-S, Control-Q,
     and Control-C is not affected by "raw" mode.

   ioctl(fd, TIOCFLUSH, 0)
     Flush current contents of tty input buffer.

   ioctl(fd, TIOCREOPEN, 0)
     Perform uart initialization sequence.  This is necessary to
     cause baud rates to change after changing environment vari-
     ables $lbaud or $rbaud.

DIAGNOSTICS
     Illegal lbaud value: %s
          An illegal baud rate value was assigned to the $lbaud
          environment variable

     Illegal rbaud value: %s
          An illegal baud rate value was assigned to the $rbaud
          environment variable

     s2681cons bad function
          An internal error was detected within the 2681 driver

     2681 overrun
          Input overflowed the 2681 input silo.  Reduce input
          rate or perform TIOCSCAN ioctl more frequently.

BUGS
     It would be more correct to consider uart ports A and B as
     units rather than controllers.  It was done this way to sim-
     plify typing.

SEE ALSO
     sable(1spp), Signetics 2681 data sheet






 Page 2                  Printed 1/6/92