COM(4) BSD Programmer's Manual COM(4)NAME
com, pccom - serial communications interface
SYNOPSIS
# amd64 and i386 - pccom or com attachments
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
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
The com and pccom drivers provide support for NS8250-, NS16450-,
NS16550-, ST16650-, and TI16750-based EIA RS-232C (CCITT V.28) communica-
tions 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
/dev/tty00
/dev/tty01
/dev/cua00
/dev/cua01
DIAGNOSTICS
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 ALSOaddcom(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
The com driver was originally derived from the HP9000/300 dca driver.
BUGS
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.
MirOS BSD #10-current July 12, 1998 1