hs.4

UNIX v6源代码 这几乎是最经典的unix版本 unix操作系统设计和莱昂氏unix源代码分析都是用的该版

.th HS IV 2/9/75
.sh NAME
hs \*- RH11/RS03-RS04 fixed-head disk file
.sh DESCRIPTION
The files
.it "hs0 ... hs7"
refer to
RJS03 disk drives 0 through 7.
The files
.it "hs8 ... hs15"
refer to
RJS04 disk drives 0 through 7.
The RJS03 drives are each 1024 blocks long and
the RJS04 drives are 2048 blocks long.
.s3
The
.it hs
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'' inteface
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 HS files begin with
.it rhs.
The same minor device considerations
hold for the raw interface as for the normal interface.
.s3
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
.it seek
calls should specify a multiple of 512 bytes.
.sh FILES
/dev/hs?, /dev/rhs?
.sh BUGS