1.\" Copyright (c) 1980, 1991 Regents of the University of California. 2.\" All rights reserved. 3.\" 4.\" %sccs.include.redist.man% 5.\" 6.\" @(#)dh.4 6.3 (Berkeley) 03/27/91 7.\" 8.Dd 9.Dt DH 4 vax 10.Os BSD 4 11.Sh NAME 12.Nm dh 13.Nd 14.Tn DH-11 Ns / Tn DM-11 15multiplexer device interface 16.Sh SYNOPSIS 17.Cd "device dh0 at uba0 csr 0160020 vector dhrint dhxint" Op Ar flags 18.Cd "device dm0 at uba0 csr 0170500 vector dmintr" Op Ar flags 19.Sh DESCRIPTION 20A 21.Tn DH-11 22provides 16 serial communication lines; 23.Tn DM-11 Ns s 24may optionally be 25paired with 26.Tn DH-11 Ns s 27to provide modem control for the lines. 28.Pp 29An optional argument 30.Ar flags 31may be supplied with the device specification 32in the 33.Xr config 8 34file indicating 35that the line corresponding to 36bit number 37.Ar i 38is not properly 39connected, and should be treated as hard-wired with carrier 40always present. Thus specifying 41.Ql flags 0x0004 42for 43.Li dh0 44would cause line 45.Pa ttyh2 46to be treated in this way. 47.Pp 48Normal I/O 49control parameters for individual lines are managed by 50.Xr ioctl 2 51calls. 52Line speeds may be initiated via 53.Xr getty 8 54and 55.Xr stty 1 56or may be communicated by other programs which 57utilize 58.Xr ioctl 59such as 60.Xr ifcongif 8 , 61see 62.Xr tty 4 . 63.Pp 64The 65.Nm dh 66driver monitors the rate of input on each board, 67and switches between the use of character-at-a-time interrupts 68and input silos. 69While the silo is enabled during periods of high-speed input, 70the driver polls for input 30 times per second. 71.Sh FILES 72.Bl -tag -width /dev/tty[h-o][0-9a-f]x -compact 73.It Pa /dev/tty[h-o][0-9a-f] 74.It Pa /dev/ttyd[0-9a-f] 75.El 76.Sh DIAGNOSTICS 77.Bl -diag 78.It dh%d: NXM. 79No response from 80.Tn UNIBUS 81on a dma transfer 82within a timeout period. This is often followed by a 83.Tn UNIBUS 84adapter 85error. This occurs most frequently when the 86.Tn UNIBUS 87is heavily loaded 88and when devices which hog the bus (such as 89.Tn RK07 Ns s) are present. 90It is not serious. 91.Pp 92.It dh%d: silo overflow. 93The character input silo overflowed 94before it could be serviced. This can happen if a hard error occurs 95when the 96.Tn CPU 97is running with elevated priority, as the system will 98then print a message on the console with interrupts disabled. 99It is not serious. 100.El 101.Sh SEE ALSO 102.Xr tty 4 103.Sh HISTORY 104A 105.Nm 106driver appeared in 107.At v6 . 108