1RK(4) Kernel Interfaces Manual RK(4)
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6 rk - RK-11/RK03 or RK05 disk
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9 Rk? refers to an entire disk as a single sequentially-addressed file.
10 Its 256-word blocks are numbered 0 to 4871. Minor device numbers are
11 drive numbers on one controller.
12 The rk files discussed above access the disk via the system's normal
14 buffering mechanism and may be read and written without regard to phys‐
15 ical disk records. There is also a `raw' interface which provides for
16 direct transmission between the disk and the user's read or write buf‐
17 fer. A single read or write call results in exactly one I/O operation
18 and therefore raw I/O is considerably more efficient when many words
19 are transmitted. The names of the raw RK files begin with rrk and end
20 with a number which selects the same disk as the corresponding rk file.
21 In raw I/O the buffer must begin on a word boundary, and counts should
23 be a multiple of 512 bytes (a disk block). Likewise seek calls should
24 specify a multiple of 512 bytes.
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27 /dev/rk?, /dev/rrk?
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30 In raw I/O read and write(2) truncate file offsets to 512-byte block
31 boundaries, and write scribbles on the tail of incomplete blocks.
32 Thus, in programs that are likely to access raw devices, read, write
33 and lseek(2) should always deal in 512-byte multiples.
34 RK(4)