Half on, half off -- New CD-R drive and 512-byte blocks

From: Jerome H. Fine <jhfinepw4z_at_compsys.to>
Date: Wed Apr 10 18:13:46 2002

>Doc wrote:

> Haven't tried my CD-RW on a non-Intel box as boot device, but I know
> that the 512-byte boot block is not the only issue. For instance, I
> have a Sony 8x reader with an IBM "microcode upgrade" that will boot my
> SparcStation, every RS6k I own, and my Alphas, ***unless*** it's a
> VMS/OpenVMS CD. The BabyVAXen also won't boot off it. The Indy won't.
> OTOH, My Plextor 32x, May It Rest In Peace (I dropped it!), would boot
> all the above except VMS CDs.
> I know that early RS/6000s did some sense checking that narrowed the
> field considerably. I _guess_ that VMS does the same. About the rest,
> I'm clueless.
> Back to reading 512-byte blocks, both my old TEAC 55R and my new
> Yamaha SCSI CDRW have a jumper to allow 512-byte reads, as do most of
> the better SCSI readers.

Jerome Fine replies:

I have a VERY old SCSI CDROM drive which seems to be able to
recognize 512 byte blocks, although I have not made a final test. It
does not recognize a CD-RW media, but I have tested it with a CD-R
that I used when I made a copy of my backup files for the complete
system.

I am using Windows 98 (which I dislike), but the Ersatz-11 emulator
runs very well under Windows 98, so I don't have a choice if I want
to run my PDP-11 programs under this emulator.

By the end of the month, I will make a copy of a bootable set of files
on a CD-R and test the SCSI CDROM drive to see if it will boot RT-11.

I do have one question for a problem I don't have a solution for. Tim
Shoppa made an RT-11 Freeware CD with files under the ISO file
structure at the beginning of the CD and other files under the RT-11
files structure at the end of the CD. Somehow (probably on a VAX
or an Alpha under VMS), he was able to master a CD with both
file structures. The essence is that there are 114,688 sectors (of
standard 2048 bytes each) of data starting at sector 212,992 (an
exact multiple of 16,384 - in this case 13 * 16,384). The 114,688
sectors hold 7 RT-11 partitions (where each partition is 16,384
sectors or 33,554,432 bytes). Under Ersatz-11, I can:
MOUNT DU1: CDROMI: (where I: is the Windows 98 drive letter)
then under RT-11, I can
SET DU1: UNIT=1,PART=13
SET DU2: UNIT=1,PART=14
....
SET DU7: UNIT=1,PART=19
At this point under RT-11, all 7 RT-11 partitions can be accessed
as DU1:, DU2:, ....., DU7:

It seems as though we have a similar requirement, although
I am already able to solve your problem. Under "Nero Burning",
the "Burn Image" option does exactly what you wish - you can
write a file on the hard disk drive to the CD-R or CD-RW
starting at sector ZERO on the CD media - IF the CD is
empty.

Sincerely yours,

Jerome Fine
--
If you attempted to send a reply and the original e-mail
address has been discontinued due a high volume of junk
e-mail, then the semi-permanent e-mail address can be
obtained by replacing the four characters preceding the
'at' with the four digits of the current year.
Received on Wed Apr 10 2002 - 18:13:46 BST

This archive was generated by hypermail 2.3.0 : Fri Oct 10 2014 - 23:34:30 BST