| WDSC(4) | Device Drivers Manual (mvme68k) | WDSC(4) | 
wdsc —
wdsc0 at pcc? ipl 2
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.
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.
| February 17, 2017 | NetBSD 10.0 |