zssc —
Zeus low level SCSI interface
The Amiga architecture uses a common machine independent scsi sub-system
  provided in the kernel source. The machine independent drivers that use this
  code access the hardware through a common interface. (see
  scsibus(4)) This common
  interface interacts with a machine dependent interface, such as
  zssc, which then handles the hardware specific issues.
The zssc interface handles things such as
    DMA and interrupts as well as actually sending commands, negotiating
    synchronous or asynchronous transfers and handling disconnect/reconnect of
    SCSI targets. The hardware that zssc uses is based
    on the NCR53c710 SCSI chip.
  - zssc%s: abort %s: dstat %02x, sstat0 %02x sbcl %02x
- The scsi operation %s was aborted due to error. Dstat, sstat and sbcl are
      registers within the NCR53c710 SCSI chip.
- siop id %d reset
- The NCR53c710 SCSI chip has been reset and configure at id %d.
- SIOP interrupt: %x sts %x msg %x sbcl %x
- The NCR53c710 SCSI chip has interrupted unexpectedly.
- SIOP: SCSI Gross Error
- The NCR53c710 SCSI chip has indicated that it is confused.
- SIOP: Parity Error
- The NCR53c710 SCSI chip has indicated that it has detected a parity error
      on the SCSI bus.
Thezssc interface first appeared in
  NetBSD 1.0