.th RF IV 10/15/73.sh NAMErf \*- RF11/RS11 fixed-head disk file.sh DESCRIPTIONThis file refers to theconcatenation of all RS-11 disks..s3Each disk contains 1024 256-word blocks.The length of the combined RF file is1024\*X(minor+1) blocks.That is minor device zerois taken to be1024 blocks long;minor device one is 2048,etc..s3The.it rf0fileaccesses the disk via the system's normalbuffering mechanismand may be read and written without regard tophysical disk records.There is also a ``raw'' interfacewhich provides for direct transmission between the diskand the user's read or write buffer.A single read or write call results in exactly one I/O operationand therefore raw I/O is considerably more efficient whenmany words are transmitted.The name of the raw RF file is.it rrf0.The same minor device considerationshold for the raw interface as for the normal interface..s3In raw I/O the buffer must begin on a word boundary,and counts should be a multiple of 512 bytes(a disk block).Likewise.it seekcalls should specify a multiple of 512 bytes..sh FILES/dev/rf0, /dev/rrf0.sh BUGSThe 512-byte restrictions on the raw device are notphysically necessary,but are still imposed.