NAME    [Toc]    [Back]

     com, pccom - serial communications interface

SYNOPSIS    [Toc]    [Back]

     # pccom or com attachments
     #
     # i386
     pccom0 at isa? port 0x3f8 irq 4
     pccom1 at isa? port 0x2f8 irq 3
     pccom2 at isa? port 0x3e8 irq 5
     pccom3 at isa? port 0x2e8 irq 9
     pccom* at isapnp?
     pccom* at pcmcia? function ?
     pccom* at puc? port ?

     pccom* at addcom? slave ?
     pccom* at ast? slave ?
     pccom* at boca? slave ?
     pccom* at hsq? slave ?
     pccom* at rtfps? slave ?

     # alpha and amd64
     com0 at isa? port 0x3f8 irq 4
     com1 at isa? port 0x2f8 irq 3

     # hppa
     com0 at gsc? offset 0x5000 irq 5
     com0 at gsc? offset 0x23000 irq 5
     com1 at gsc? offset 0x22000 irq 6
     com2 at gsc? offset ? irq 13
     com1 at dino? irq 11

     # sparc64
     com* at asio?
     com* at ebus?

DESCRIPTION    [Toc]    [Back]

     The com and  pccom  drivers  provide  support  for  NS8250-,
NS16450-,
     NS16550-,  ST16650-,  and  TI16750-based  EIA RS-232C (CCITT
V.28) communications
 interfaces.  The pccom driver  (i386-only)  also  supports the XR16850
     UART.

     The  NS8250  and  NS16450 have single character buffers, the
NS16550 has a
     16 character buffer, while the ST16650 has  a  32  character
buffer, and the
     TI16750  has  a  64 character buffer.  The XR16850 has a 128
character
     buffer.

     The com and pccom drivers are mutually exclusive;  both  may
not be present
     in  the same system at the same time.  Attempting to compile
such a system
     will fail.

     Input and output for each line may be set to one of  following baud rates;
     50,  75,  110, 134.5, 150, 300, 600, 1200, 1800, 2400, 4800,
9600, 19200,
     38400, 57600, or 115200, or any other baud rate which  is  a
factor of
     115200.

FILES    [Toc]    [Back]

     /dev/tty00
     /dev/tty01
     /dev/cua00
     /dev/cua01

DIAGNOSTICS    [Toc]    [Back]

     com%d:  %d silo overflows  The input ``silo'' has overflowed
and incoming
     data has been lost.

     com%d: weird interrupt: iir=%x  The device has generated  an
unexpected
     interrupt with the code listed.

SEE ALSO    [Toc]    [Back]

     addcom(4),   asio(4),  ast(4),  boca(4),  dino(4),  ebus(4),
gsc(4), hsq(4),
     intro(4), isa(4), isapnp(4),  pcmcia(4),  puc(4),  rtfps(4),
tty(4)

HISTORY    [Toc]    [Back]

     The  com  driver  was originally derived from the HP9000/300
dca driver.

BUGS    [Toc]    [Back]

     Data loss is possible on busy systems with unbuffered  UARTs
at high
     speed.

     The  name  of this driver and the constants which define the
locations of
     the various serial ports are holdovers from DOS.

OpenBSD     3.6                           July      12,      1998