com, pccom - serial communications interface
# 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 and amd64
com0 at isa? port 0x3f8 irq 4
com1 at isa? port 0x2f8 irq 3
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
com* at asio?
com* at ebus?
The com and pccom drivers provide support for NS8250-,
NS16550-, ST16650-, and TI16750-based EIA RS-232C (CCITT
interfaces. The pccom driver (i386-only) also supports the XR16850
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
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
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,
38400, 57600, or 115200, or any other baud rate which is a
com%d: %d silo overflows The input ``silo'' has overflowed
data has been lost.
com%d: weird interrupt: iir=%x The device has generated an
interrupt with the code listed.
addcom(4), asio(4), ast(4), boca(4), dino(4), ebus(4),
intro(4), isa(4), isapnp(4), pcmcia(4), puc(4), rtfps(4),
The com driver was originally derived from the HP9000/300
Data loss is possible on busy systems with unbuffered UARTs
The name of this driver and the constants which define the
the various serial ports are holdovers from DOS.
OpenBSD 3.6 July 12, 1998
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