.\" $NetBSD: wdsc.4,v 1.6 2017/02/17 22:24:47 christos Exp $
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.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Steve C. Woodford.
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.Dd February 17, 2017
.Dt WDSC 4 mvme68k
.Os
.Sh NAME
.Nm wdsc
.Nd Western Digital WD33c93 SCSI Bus Interface Controller
.Sh SYNOPSIS
.Cd "wdsc0 at pcc? ipl 2"
.Sh DESCRIPTION
The
.Nm
driver provides an abstraction layer between the SCSI hardware
fitted to the
.Tn Motorola
MVME147 single board computer (WD33C93), and the machine
independent SCSI drivers described in
.Xr scsibus 4 .
.Pp
In addition to sending the required SCSI commands to
target devices on the SCSI bus, the
.Nm
driver deals with DMA, device interrupts, sync/async negotiation
and target disconnects/reconnects.
.Sh DIAGNOSTICS
Too many to mention.
.Sh SEE ALSO
.Xr mvme68k/pcc 4 ,
.Xr scsibus 4
.Sh BUGS
Negotiation of Synchronous SCSI data transfers has been
deliberately disabled in the MVME147's
.Nm
driver as it has proved extremely difficult to make it
work reliably in this mode.
.Pp
The
.Nm
driver does not respond well to exceptional conditions
caused by poor SCSI cabling and/or termination. In those
instances the machine is likely to require a hard reset
to recover.
.Pp
The current
.Nm
driver should be blown away and replaced with a machine independent
version.