NAME

hp − RH-11/RP04 moving-head disk

DESCRIPTION

The files "hp0 ... hp7" refer to sections of RP disk drive 0.  The files "hp8 ... hp15" refer to drive 1 etc.  This is done since the size of a full RP drive is 170,544 blocks and internally the system is only capable of addressing 65536 blocks.  Also since the disk is so large, this allows it to be broken up into more manageable pieces.  The origin and size of the pseudo-disks on each drive are as follows: diskstartlength
009614
11839265535
24801865535
314964420900
4040600
54180040600
68360040600
712540040600 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. The hp 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 rhp and end with a number which selects the same disk section as the corresponding hp 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/hp?, /dev/rhp? 

BUGS