crl —
VAX-8600 console RL02 interface
This is a simple interface to the DEC RL02 disk unit which is part of the
  console subsystem on the VAX-8600 and 8650. Access is given to the entire RL02
  disk; the pack format is the same as that of RL02 disks on other controllers.
  As on other VAX console media, transfers are done a word at a time using
  privileged registers (i.e., slowly).
All I/O is raw; the seek addresses in raw transfers should be a
    multiple of 512 bytes and a multiple of 512 bytes should be transferred, as
    in other “raw” disk interfaces. (Although the sector size is
    actually 256 bytes, the driver allows operations only on 512-byte
    boundaries.)
The crl driver appeared in
  4.3BSD.