12 Jan
2006
12 Jan
'06
12:28 a.m.
Thanks Jerome for this information.
I did know what the WRITE PROT button does :-), but the fact
that you can run RT-11 with that button ON was new to me,
as long as you don't need to write to the pack, of course.
Very handy if you make any copy from the system disk to an
other disk. An error in the entry line (DL0 <-> DL1: swapped)
will not be harmful to the system disk with the WRITE PROT
button ON. I used your tip yesterday!
I did notice however, that I became a little less "on guard",
because I was thinking "I'am safe" :-)
BTW, as you can guess, my problems with the RL drives that
would not boot are solved. The drive(s), cables and the pack
are all fine, the RL11 controller developed a fault.
I have tagged the board with a label that describes the
symptoms and put it aside ... for days when I have more time
to do some fault finding on the board; when I'm retired :-).
- Henk, PA8PDP.
Jerome Fine replies:
Tony is correct. The boot block does start with 240 for the
RL02. If you know the approximate version of RT-11 and the
flavour of the monitor (RT11FB, RT11XM, etc.), most of the
rest of the boot block at block zero can be described. Of
course, if you did that, you also would have read the RL02 pack!
One method of making sure that the RL02 pack is not changed
is to WRITE PROTECT the pack so that it can't be changed -
PERIOD! While some operating systems can't run, RT-11 is
PERFECTLY happy using this method of making sure that the
system disk (or any other for that matter) is not altered.
Of course, you also can't save any new files. BUT, you can
turn off the WRITE PROTECT at any time and save one file at a
time when you actually have something to save. NOTE that
RT-11 must also write first to the directory, so if you use
this method, best to use VM: and copy the file in one
operation using PIP after the file is complete.
Sincerely yours,
Jerome Fine
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