v7 man page for rf

RF(4)							     Kernel Interfaces Manual							     RF(4)

NAME
       rf - RF11/RS11 fixed-head disk file

DESCRIPTION
       This file refers to the concatenation of all RS-11 disks.

       Each  disk contains 1024 256-word blocks.  The length of the combined RF file is 1024x(minor+1) blocks.	That is minor device zero is taken
       to be 1024 blocks long; minor device one is 2048, etc.

       The rf0 file accesses the disk via the system's normal buffering mechanism and may be read and written  without	regard	to  physical  disk
       records.   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  name  of  the  raw  RF file is rrf0.  The same minor device considerations hold for the raw interface as for the normal
       interface.

       In raw I/O the buffer must begin on a word boundary, and counts should be a multiple of 512 bytes (a  disk  block).   Likewise  seek  calls
       should specify a multiple of 512 bytes.

FILES
       /dev/rf0, /dev/rrf0

BUGS
       The 512-byte restrictions on the raw device are not physically necessary, but are still imposed.

																	     RF(4)