NAME

rp − RP-11/RP03 moving-head disk

DESCRIPTION

The files rp0, ..., rp7 refer to sections of the RP03 disk drive 0.  The files rp10, ..., rp17 refer to drive 1, etc.  This slicing allows the pack to be broken up into more manageable pieces. 

The origin and size of the sections on each drive are as follows:

sectionstartlength
0010000
15071200
220340600
3−−
4−−
5−−
6−−
7081200

The start address is a cylinder address, with each cylinder containing 200 blocks.  It is extremely unwise for all of these files to be present in one installation, since there is overlap in addresses and protection becomes a sticky matter. 

The rp 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 RP files begin with rrp and end with a number which selects the same disk section as the corresponding rp 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 lseek calls should specify a multiple of 512 bytes. 

FILES

/dev/rp∗, /dev/rrp∗

SEE ALSO

hp(4). 

May 16, 1980  —  PDP-11 obsolete