CD-ROM on RT-11?

From: Jerome H. Fine <>
Date: Fri Mar 22 10:39:52 2002

"Zane H. Healy" wrote:

> >While I can burn a CD with the ISO file structure, I would very much like
> >to set up some RT-11 partitions to be used under E11 - like were done
> >with the RT-11 Freeware CD.
> I've been wondering if it's possible to create a image of a MSCP disk (a
> RA82 looks to be the best bet) under either E11 or SIMH, and then burn it
> to CD-R. I know that RL01 and RL02 images are directly transferable, and
> the same looks to be true for RX02 and RX50 images.

Jerome Fine replies:

As Zane may remember, under Windows 98, when I use the E11 command:
I am able to see almost the whole CD under RT-11 EXCEPT the first
64 decimal (100 octal) blocks. Can anyone comment on this aspect?

To help anyone understand, when I boot RT-11 under E11 under Windows 98,
the CD (having used the above command under E11) will appear as 20 RT-11
partitions of exactly 65536 "blocks" (32 MBytes) each - assuming that the CD
has been written to the highest possible "block". Each "block" will still be
bytes even though on the CD the "sector" size is 2048 bytes. This means that
the CD is divided into partitions of exactly 16384 "sectors" that are 2048
each - even though RT-11 will see it the other way (i.e. 512 byte blocks).

However, the first 64 blocks of 512 bytes are NOT readable under Windows 98.
I have NEVER had the ability to use the same CD in a CDROM drive under
RT-11 on a real PDP-11, but I get the impression that under that set-up, the
first 64 blocks can be read. In that case, it would even be possible to have
the real PDP-11 do a hardware boot from partition zero is everything on the
CD was set-up correctly. Can anyone comment on this question?

ALSO, I noticed a reference in previous post in respect of the notation
used to write to a specific block on the destination. Tom suggested:
dd if=/dev/rz4c ibs=64k obs=64k | cdrecord -dev 3,5,0 -speed=2 -
but I would appreciate some idea of what the actual syntax is for
the command?

By the way, Doc, I have downloaded the dd.exe file - thank you.
Of course there was no documentation. Perhaps that is available
somewhere as well? Also, can I use this technique to "Burn" a
CD that has already had the first portion written with an ISO file
structure? Was this how Tim Shoppa prepared the RT-11
Freeware CD? If I seem totally confused by the nature of the
questions I am asking, you are correct!

Sincerely yours,

Jerome Fine
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Received on Fri Mar 22 2002 - 10:39:52 GMT

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