HP(4)

NAME
hp - RH-11/RP04, RP05, RP06, RM03 moving-head disk

DESCRIPTION
Files with minor device numbers 0 through 7 refer to various portions of drive 0; minor devices 8 through 15 refer to drive 1, etc.

The origin and size of the pseudo-disks on each drive are as follows:

RP partitions
    disk    start    length
    0    0    15884
    1    15884    33440
    2    40964    8360
    3    0    0
    4    0    0
    5    0    0
    6    49324    291346
    7    0    0

RM partitions
    disk    start    length
    0    0    15884
    1    16000    33440
    2    0    0
    3    0    0
    4    0    0
    5    0    0
    6    49600    82080
    7    0    0

It is unwise for all of these files to be present in one installation, since there is overlap in addresses and protection becomes a sticky matter. Ordinarily devices 0 and 6 (or 0 and 7) will be used.

The block files 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 files conventionally begin with an extra `r.'

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/rp?, /dev/rrp?

SEE ALSO
rp(4)