>"Zane H. Healy" wrote:
> > So will this guy boot from Tim Shoppa's RT-11 CD?
> No, none of Tim's CD's are bootable. Also, be aware, that it isn't exactly
> easy to find a hardware combination that will allow a PDP-11 to talk to a
> CD-ROM. I use a Viking SCSI controller (which needs almost current ROMs to
> be able to handle CD-ROM's) and a DEC RRD-42.
Jerome Fine replies:
I think I finally figured out a method of creating a bootable CD
under RT-11 which also holds a set of files under the ISO file
structure.
I don't know if it will work under anything but DOS/W95/W98,
but here goes.
Note that I have noticed that there may be some hardware/software
problems with one of the SCSI CDROM drive I am using, so
I suspect that this whole procedure may take a bit of time to work out.
If anyone is interested enough to follow all of the details, I would
appreciate helpful comments. The key point is that I will likely
use RT-11 to solve the problem of transferring the data to the
hard disk file "BurnImage.DSK" which will be used to hold
all the data until it is ready to be transferred to the final CD.
As such, I still need to modify the DUP.SAV program so
that I can easily copy block 65535 of an RT-11 partition to
the last block of all of the non-RT-11 partitions at the start
of the disk file "BurnImage.DSK" - right now, the DEC
distributions will read, but not write block 65535. There is
a simple way around this problem and I will use the work
around the first few times.
First, I make the assumption that DOS/W95/W98 allow readable
sectors in the area of sectors zero to 15 (sectors are 2048 bytes
each). I did a "DUMP" under "Nero Burning" and in every case,
where I had set up only an ISO file structure, all 16 sectors had
2048 bytes of zeros. Where I had an RT-11 file structure, the
correct data was there instead. I will first try all this out with
a CD-RW (erasable CD).
(a) Create the CD with the files that the user wants to have under the
ISO file structure with ONE additional file which MUST be contained
within the first 32 MBytes or 16383 sectors (of 2048 bytes each) on
the CD. This additional file will be the RT-11 DSK file that I want
to be bootable.
(b) After I create the CD with the files that I want to be there under
the ISO file, I use PUTR to create a file on the hard disk that will be
exactly the number of bytes which I will eventually use for the "Burn
Image" option. The size of BurnImage.DSK will be an integer
multiple of 33,554,432 bytes. The fist portion covers the files
under the ISO file structure. The second portion covers the
files under the RT-11 files structure. Normally, the maximum
size will be 20 RT-11 partitions or 671,088,640 bytes.
(c) Under E11, I will mount both:
MOUNT DU0: CDROME:/RONLY
MOUNT DU1: BurnImage.DSK
after which I will run RT-11 and copy each 65536 block partition
from DU0: from the CD to the hard disk file.
(d) This is now the tricky part. That bootable DSK file which
is also a file under the ISO file structure must be located somewhere
in BurnImage.DSK in the first 32 MBytes. I am not sure yet if it will
start on a sector boundary, but after it is found, I will need to set up
the RT-11 fist structure in the first 64 blocks of BurnImage.DSK
by putting a dummy file in that file structure immediately in front of
the first file in that bootable.DSK file. Alternatively, I suspect that
the starting block number can be set to be the correct start of the
first file in the bootable.DSK, so a bit of calculations will be needed.
(e) Finally, the RT-11 partitions in the second portion will
be copied to the RT-11 partitions in hard disk file.
Sincerely yours,
Jerome Fine
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Received on Sun Apr 14 2002 - 23:35:59 BST