10 Apr
2002
10 Apr
'02
6:13 p.m.
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
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