com(4) - NetBSD Manual Pages

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COM(4)                    NetBSD Programmer's Manual                    COM(4)

com - serial communications interface
com0 at isa? port "IO_COM1" irq 4 com1 at isa? port "IO_COM2" irq 3 com* at cardbus? com* at isapnp? com* at mca? slot ? com* at mhzc? com* at ofisa? com* at pcmcia? com* at pcmcom? com* at pnpbios? index ? com* at puc? port ? Arm32 com0 at mainbus? base 0x00210fe0 com1 at mainbus? base 0x00210be0
The com driver provides support for NS8250-, NS16450-, and NS16550-based EIA RS-232C (CCITT V.28) communications interfaces. The NS8250 and NS16450 have single character buffers, and the NS16550 has a 16 character buffer. Input and output for each line may 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. The ttyXX devices are traditional dialin devices; the dtyXX devices are used for dialout. (See tty(4).) Arm32 specific If ``flags 1'' is specified, the com driver will not set the MCR_IENABLE bit on the UART. This is mainly for use on AST multiport boards, where the MCR_IENABLE bit is used to control whether or not the devices use a shared interrupt.
/dev/dty00 /dev/dty01 /dev/dty02 /dev/tty00 /dev/tty01 /dev/tty02
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.
ast(4), cardbus(4), isa(4), isapnp(4), mca(4), mhzc(4), ofisa(4), pcmcia(4), pcmcom(4), pnpbios(4), puc(4), rtfps(4), tty(4)
The com driver was originally derived from the HP9000/300 dca driver.
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. NetBSD 1.6.2 April 20, 2001 2
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