NAME
wdsc —
Western Digital WD33c93 SCSI Bus
Interface Controller
SYNOPSIS
wdsc0 at pcc? ipl 2
DESCRIPTION
The
wdsc driver provides an abstraction layer between the SCSI
hardware fitted to the Motorola MVME147 single board computer (WD33C93), and
the machine independent SCSI drivers described in
scsibus(4).
In addition to sending the required SCSI commands to target devices on the SCSI
bus, the
wdsc driver deals with DMA, device interrupts,
sync/async negotiation and target disconnects/reconnects.
DIAGNOSTICS
Too many to mention.
SEE ALSO
mvme68k/pcc(4),
scsibus(4)
BUGS
Negotiation of Synchronous SCSI data transfers has been deliberately disabled in
the MVME147's
wdsc driver as it has proved extremely
difficult to make it work reliably in this mode.
The
wdsc 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.
The current
wdsc driver should be blown away and replaced with
a machine independent version.