.TH HS 4 
.UC
.SH NAME
hs \- RH11, RH70/RS03, RS04 fixed-head disk
.SH DESCRIPTION
The files
.I "hs0 ... hs7"
refer to
RS03 disk drives 0 through 7.
The files
.I "hs8 ... hs15"
refer to
RS04 disk drives 0 through 7.
The RS03 drives are each 1024 512-byte blocks long and
the RS04 drives are 2048 512-byte blocks long.
.PP
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' 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 files conventionally begin with
an extra `r.'
.PP
In raw I/O counts should be a multiple of 512 bytes
(a disk sector).  Likewise,
.I lseek
calls should specify a multiple of 512 bytes.
.SH FILES
.ta 2i
/dev/hs??	block files
.br
/dev/rhs??	raw files
.SH "SEE ALSO"
dvhp(4), hk(4), hp(4), ml(4), rf(4), rk(4), rl(4), rm(4), rp(4), rx2(4), xp(4)
.SH DIAGNOSTICS
\fBhs%d: hard error bn %d cs1=%b cs2=%b\fP.  An unrecoverable
error occured during transfer of the specified sector of the specified
disk partition.  The contents of the two error registers are also printed
in octal and symbolically with bits decoded.
The error was either unrecoverable, or a large number of retry attempts
could not recover the error.
.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.
.PP
DEC-standard error logging should be supported.
.PP
A program to analyze the logged error information (even in its
present reduced form) is needed.