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
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.