.TH ML 4
.UC
.SH NAME
ml \- RH-11, RH-70/ML-11 solid state disk
.SH DESCRIPTION
The standard device names begin with ``ml'' followed by
the drive number.
The character ? stands here for a drive number in the range 0-7.
The size of each ML-11 unit depends on the number of array modules
installed.  There are 512 512-byte blocks per array module, for
a maximum size of 8192 blocks per unit.
The ML-11 may be used for the swap device or perhaps mounted on /tmp.
.PP
The ML-11 has switch-selectable transfer rates of 0.25Mb, 0.5Mb,
1.0Mb, and 2.0Mb per second.  The following transfer rate restrictions
apply:
.PP
.nf
.ta 0.5i +\w'0000000    'u +\w'0000000    'u

	rate	permissible PDP-11 CPUs
	0.25 Mb	all
	0.5  Mb	all
	1.0  Mb	PDP-11/70 with RH-70 only
	2.0  Mb	none
.DT
.fi
.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' 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 files
conventionally begin with an extra `r.'
.PP
In raw I/O counts should be a multiple of 512 bytes (a disk sector).
Likewise
.IR lseek (2)
calls should specify a multiple of 512 bytes.
.SH FILES
.ta 2i
/dev/ml[0-7]	block files
.br
/dev/rml[0-7]	raw files
.SH "SEE ALSO"
dvhp(4), hk(4), hp(4), hs(4), rf(4), rk(4), rl(4), rm(4), rp(4), rx2(4), xp(4)
.SH DIAGNOSTICS
\fBml%d: hard error bn %d cs2=%b er=%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 unrecoverable.
.PP
\fBML11 xfer rate error\fP.  The selected transfer rate for the ML11
did not conform to the restrictions above.
.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
The
.I ml
disk driver requires that the ML-11 be installed on a separate
RH-11 or RH-70 MASSBUS disk controller.