[unix-history] / usr / man / man4 / rp.4

.TH RP 4 
.SH NAME
rp \- RP-11/RP03 moving-head disk
.SH DESCRIPTION
The files
.I "rp0 ... rp7"
refer to sections of RP disk drive 0.
The files
.I "rp8 ... rp15"
refer to drive 1 etc.
This allows a large disk to be broken up
into more manageable pieces.
.PP
The origin and size of the pseudo-disks on each drive are
as follows:
.PP
.br
	disk	start	length
.br
	0	0	81000
.br
	1	0	5000
.br
	2	5000	2000
.br
	3	7000	74000
.br
	4-7	unassigned
.PP
Thus rp0 covers the whole drive,
while rp1, rp2, rp3 can serve usefully as a root, swap, and
mounted user file system respectively.
.PP
The
.I 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
.I rrp
and end with a number which selects the same disk
section as the corresponding
.I rp
file.
.PP
In raw I/O the buffer must begin on a word boundary.
.SH FILES
/dev/rp?, /dev/rrp?
.SH SEE ALSO
hp(4)
.SH BUGS
In raw I/O
.I read
and
.IR write (2)
truncate file offsets to 512-byte block boundaries,
and
.I write
scribbles on the tail of incomplete blocks.
Thus,
in programs that are likely to access raw devices,
.I read, write
and
.IR lseek (2)
should always deal in 512-byte multiples.
Commit	Line	Data
70b96c2d DR	1	.TH RP 4
	2	.SH NAME
	3	rp \- RP-11/RP03 moving-head disk
	4	.SH DESCRIPTION
	5	The files
	6	.I "rp0 ... rp7"
	7	refer to sections of RP disk drive 0.
	8	The files
	9	.I "rp8 ... rp15"
	10	refer to drive 1 etc.
	11	This allows a large disk to be broken up
	12	into more manageable pieces.
	13	.PP
	14	The origin and size of the pseudo-disks on each drive are
	15	as follows:
	16	.PP
	17	.br
	18	disk start length
	19	.br
	20	0 0 81000
	21	.br
	22	1 0 5000
	23	.br
	24	2 5000 2000
	25	.br
	26	3 7000 74000
	27	.br
	28	4-7 unassigned
	29	.PP
	30	Thus rp0 covers the whole drive,
	31	while rp1, rp2, rp3 can serve usefully as a root, swap, and
	32	mounted user file system respectively.
	33	.PP
	34	The
	35	.I rp
	36	files
	37	access the disk via the system's normal
	38	buffering mechanism
	39	and may be read and written without regard to
	40	physical disk records.
	41	There is also a `raw' interface
	42	which provides for direct transmission between the disk
	43	and the user's read or write buffer.
	44	A single read or write call results in exactly one I/O operation
	45	and therefore raw I/O is considerably more efficient when
	46	many words are transmitted.
	47	The names of the raw RP files
	48	begin with
	49	.I rrp
	50	and end with a number which selects the same disk
	51	section as the corresponding
	52	.I rp
	53	file.
	54	.PP
	55	In raw I/O the buffer must begin on a word boundary.
	56	.SH FILES
	57	/dev/rp?, /dev/rrp?
	58	.SH SEE ALSO
	59	hp(4)
	60	.SH BUGS
	61	In raw I/O
	62	.I read
	63	and
	64	.IR write (2)
65	truncate file offsets to 512-byte block boundaries,
66	and
67	.I write
68	scribbles on the tail of incomplete blocks.
69	Thus,
70	in programs that are likely to access raw devices,
71	.I read, write
72	and
73	.IR lseek (2)
74	should always deal in 512-byte multiples.