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4 .\" This code is derived from software contributed to Berkeley by
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35 .\" from: @(#)dca.4 5.2 (Berkeley) 3/27/91
36 .\" from: com.4,v 1.1 1993/08/06 11:19:07 cgd Exp
45 fast interrupt serial communications interface
47 .Cd "device sio0 at isa? port" \&"IO_COM1\&" tty irq 4 vector siointr
48 .Cd "device sio1 at isa? port" \&"IO_COM2\&" tty irq 3 vector siointr
49 .Cd "device sio2 at isa? port" \&"IO_COM3\&" tty irq 5 vector siointr
50 .Cd "device sio3 at isa? port" \&"IO_COM4\&" tty irq 9 vector siointr
54 driver provides support for NS8250-, NS16450-, and NS16550-based
59 communications interfaces. The NS8250 and NS16450 have single character
60 buffers, and the NS16550 has a 16 character buffer.
62 Input and output for each line may set to one of following baud rates;
63 50, 75, 110, 134.5, 150, 300, 600, 1200, 1800, 2400, 4800, 9600,
64 19200, 38400, 57600, or 115200.
72 .It sio%d: silo overflow.
73 The single-character input
75 has overflowed and incoming data has been lost.
76 .\".It com%d: weird interrupt: %x.
77 .\"The device has generated an unexpected interrupt
78 .\"with the code listed.
86 driver is derived from the
92 Data loss is not near as likely on busy systems as they are with the
94 driver but they still can occur at very high baud rates on slow systems.
96 The constants which define the locations
97 of the various seiral ports are holdovers from
100 As usual, you get what you pay for; cheap NS16550 clones
101 generally don't work.