You have to use the LD driver. Myself I use a smaller
drive as 32mb for
RT-11 is a very roomy disk. A Quantum D540(rd52) at 32mb is perfect,
are also cooler and far more reliable. Another good choice is an St225
(rd31) at 20mb it's still large for a RT-11 system.
Jerome Fine replies:
I think you are confusing the use of the LDX.SYS logical device
driver along with dividing the 32 MB hard drive partitions into files,
each of which have their own RT-11 directory, and the DUX.SYS
device driver which has about 159 MB or about 5 RT-11 partitions.
I agree that 65535 blocks for an RT-11 device is usually far too large
for a single RT-11 directory when the maximum number of files is about
2000 files per RT-11 directory in any case. BUT, using LDX.SYS
is very separate, in my opinion, from how DUX.SYS divides the RD54
into 5 RT-11 partitions.
Of course, if you have a 2 GB hard drive (or SIMH with a file) which can
hold 64 RT-11 partitions, then starting with V05.05 of RT-11, extended
DU(X).SYS allowed 64 RT-11 partitions to be available at the SAME
time. And if you have a hard drive or a file of 8 GB, then 256 RT-11
partitions are available in total via the:
SET DUn: UNIT=u, PART=255
except that a maximum of only 8 RT-11 partitions can be specified in
each DU(X).SYS device driver at one time with V05.03 of RT-11.
I doubt VERY much that anyone is interested in a larger number of
RT-11 partitions per DU(X).SYS device driver, but it would be
fairly easy to allow up to 65536 RT-11 partitions for each unit, just
not all at the same time. At the moment, the 2 word internal table
allows 16 bits for the UNIT, 8 bits for the PART and 8 bits for
the PORT (physical controller or host adapter). Since I have
never EVER seen a UNIT of larger than 255 used, the switch
between UNIT and PART would be easy, especially since
a value of n > 255 is not allowed in the SET command in any
You should be
able to find what you are looking for in the RT-11 docs
for versions of RT-11 > V05.04, at least. Dunno about < V05.04
Starting with V05.03 of RT-11, DU(X).SYS allowed a large
hard disk drive (> 32MB) to be divided into 32 MB RT-11
partitions, or more specifically, for the portions of
the hard drive beyond 32 MB to be accessed as RT-11
partitions. The MSCP DU(X).SYS device driver first
became available (with a few bugs that were fixed by
V05.03 of RT-11) with V05.00 of RT-11 in 1983. V05.03
of RT-11 was released in 1985.
LD(X).SYS was released with V05.00 in 1983. It was an
integrated device driver (with RT-11) of a DECUS device
driver that had been available for many years. I suppose
that DEC finally realized that if DECUS people could do
the code, then DEC had better do the integrated job when
V05.00 was released. Since V04.00 did not know when physical
devices were being used, if the hard drive files were
"SQUEEZED", especially on the system device, all of the
pointers had to be reset to the logical devices. Not a
difficult coding problem, but changes were required in
V05.00 to allow for LD(X).SYS to function correctly.
In general, LD(X).SYS provided RT-11 with a set of
sub-directories. What is still missing from RT-11
is what VMS has called Logical Name List - or what
I suggest in RT-11 be called the Symbolic Translation
device driver with a name of ST(X).SYS which would
allow what DOS calls a PATH NAME list. However,
ST(X).SYS would apply to ALL EXISTING files being
opened via the .LookUp EMT and the user would be
allowed to specify up to 16 physical devices for each
unit in the Symbolic Translation device driver, i.e.
ST3: => DU0:, DU1:, LD0:, LD1:, etc.
SET ST3: DEVICEA=DU0
SET ST3: DEVICEB=DU1
SET ST3: DEVICEC=LD0
SET ST3: DEVICED=LD1
A .LookUp EMT request for ST3:FOOBAR.TST would check
all of the specified physical device names in the
order specified before returning a File Not Found error.
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