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.