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rf(4) [v7 man page]

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)

Check Out this Related Man Page

RK(4)							     Kernel Interfaces Manual							     RK(4)

NAME
rk - RK-11/RK03 or RK05 disk DESCRIPTION
Rk? refers to an entire disk as a single sequentially-addressed file. Its 256-word blocks are numbered 0 to 4871. Minor device numbers are drive numbers on one controller. The rk files discussed above access 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 names of the raw RK files begin with rrk and end with a number which selects the same disk as the corre- sponding rk file. 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/rk?, /dev/rrk? BUGS
In raw I/O read and write(2) truncate file offsets to 512-byte block boundaries, and write scribbles on the tail of incomplete blocks. Thus, in programs that are likely to access raw devices, read, write and lseek(2) should always deal in 512-byte multiples. RK(4)
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