Post by David Coolbear
OK, I almost hate to ask the question, because it's probably obvious, but,
how does one create and format partitions on a drive in RT-11? If you do
a 'show devices' then it seems to indicate that the DU device can have
multiple partitions, but I'm wondering how to create them.
Jerome Fine replies:
FIRST, understand that in the DEC world with a PDP-11,
FORMAT is very different from the Windows world where
FORMAT includes the setting of of the file structure of a device.
With a PDP-11 in general and RT-11 in particular, FORMAT
is ONLY (except for a few exceptions with 8" floppy media)
with respect to the LLF (low level format) of a complete device.
INITIALIZE in RT-11 is used to set up the file structure of a
device after RT-11 is running. So it is necessary to have at least
one working RT-11 device to INIT a second device or RT-11
Each RT-11 partition is exactly 65536 blocks long except for the
last RT-11 partition on the device which uses what is left of the
device. RT-11 currently supports up to 256 partitions on a
device which is 8 GBytes or 256 * 65536 blocks.
If you are using a large SCSI drive with the DU(X).SYS device
driver, then you first set up a map entry via:
SET DUn: PORT=c, UNIT=u, PART=p
for standard DEC distributed monitors after V05.03 of RT-11.
n = logical unit number ( 0 <=n <= 7)
c = controller number (0 <= c <= 3)
u = physical unit number (0 <= u <= 255)
p = partition number (0 <= p <= 255)
Starting with V05.06 of RT-11, DEC finally added the one
missing instruction to the boot program which allowed DUP.SAV
to boot NON-ZERO partitions.
If you have a non-DEC controller which supports partitions
so that you seem to have multiple UNIT numbers for each
physical hard drive, then it is possible to have separate unit
numbers for RT-11. But, if any portion of the hard drive is
already has a FORMAT, then all of the hard drive has a FORMAT
and ONLY an INIT is needed to use the other UNITs under
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