css —
DEC IMP-11A LH/DH IMP network interface
pseudo-device imp device css0 at uba0 csr 167600 flags 10
  vector cssrint cssxint
NOTE: At the moment, NetBSD does not support IMP, so
  this manual page is not relevant.
The css device provides a Local
    Host/Distant Host interface to an IMP. It is normally used when
    participating in the DARPA Internet. The controller itself is not accessible
    to users, but instead provides the hardware support to the IMP interface
    described in imp(4). The
    configuration entry for the
    imp(4) must also include the
    pseudo-device as shown above.
  - css%d: not alive.
- The initialization routine was entered even though the device did not
      autoconfigure. This is indicates a system problem.
- css%d: can't initialize.
- Insufficient UNIBUS resources existed to initialize the device. This is
      likely to occur when the device is run on a buffered data path on an
      11/750 and other network interfaces are also configured to use buffered
      data paths, or when it is configured to use buffered data paths on an
      11/730 (which has none).
- css%d: imp doesn't respond, icsr=%b.
- The driver attempted to initialize the device, but the IMP failed to
      respond after 500 tries. Check the cabling.
- css%d: stray output interrupt csr=%b.
- An interrupt occurred when no output had previously been started.
- css%d: output error, ocsr=%b icsr=%b.
- The device indicated a problem sending data on output.
- css%d: recv error, csr=%b.
- The device indicated a problem receiving data on input.
- css%d: bad length=%d.
- An input operation resulted in a data transfer of less than 0 or more than
      1008 bytes of data into memory (according to the word count register).
      This should never happen as the maximum size of a host-IMP message is 1008
      bytes.
Thecss interface appeared in
  4.2BSD.