.\"	$OpenBSD: wd.4,v 1.4 1999/07/21 23:57:55 aaron Exp $
.\"	$NetBSD: wd.4,v 1.4 1999/04/25 00:00:05 mjl Exp $
.\"
.\"
.\" Copyright (c) 1994 James A. Jegers
.\" All rights reserved.
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.Dd October 15, 1998
.Dt WD 4 
.Os
.Sh NAME
.Nm wd 
.Nd WD100x compatible hard disk driver
.Sh SYNOPSIS
.Cd "wd* at wdc? channel ? drive ? flags 0x0000"
.Cd "wd* at pciide? channel ? drive ? flags 0x0000"
.Sh DESCRIPTION
The
.Nm
driver supports hard disks which emulate the Western Digital WD100x.
This includes standard MFM, RLL, ESDI, IDE, and EIDE drives.
.Pp
The
.Cm flags
are used only with controllers that support DMA operations and
mode settings (like some
.Xr pciide 4
controllers).
The lowest order (right-most) nibble of the
.Cm flags
define the PIO mode to use. The next four bits indicate the DMA mode and the
third nibble the UltraDMA mode.
.Pp
For each set of four bits, the 3 lower bits define the mode to use
and the last bit must be set to 1 for this setting to be used.
For DMA and UltraDMA, 0xf (1111) means
.Dq disable .
For example, a
.Cm flags
value of 0x0fac (1111 1010 1100) 
means
.Do
use PIO mode 4, DMA mode 2, disable UltraDMA
.Dc .
The special setting 0x0000 means
.Dq use whatever the drive claims to support .
.Sh SEE ALSO
.Xr intro 4 ,
.Xr pciide 4 ,
.Xr scsi 4 ,
.Xr wdc 4