RF(IV) 10/15/73 RF(IV)
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.