rp \- RP-11/RP03 moving-head disk
refer to sections of RP disk drive 0.
This allows a large disk to be broken up
into more manageable pieces.
The origin and size of the pseudo-disks on each drive are
Thus rp0 covers the whole drive,
while rp1, rp2, rp3 can serve usefully as a root, swap, and
mounted user file system respectively.
access the disk via the system's normal
and may be read and written without regard to
There is also a `raw' interface
which provides for direct transmission between the disk
and the user's read or write buffer.
A single read or write call results in exactly one I/O operation
and therefore raw I/O is considerably more efficient when
many words are transmitted.
The names of the raw RP files
and end with a number which selects the same disk
section as the corresponding
In raw I/O the buffer must begin on a word boundary.
truncate file offsets to 512-byte block boundaries,
scribbles on the tail of incomplete blocks.
in programs that are likely to access raw devices,
should always deal in 512-byte multiples.