Slightly OT: Help? Apple CD 300 and VAX 4000 VLC

From: Hans Hübner <>
Date: Wed Jun 27 13:17:30 2001

On Wed, 27 Jun 2001, Mark Tapley wrote:

> Help? In the absence of any clues, I'll probably take apart the CD300 to
> see if I can spot anything obviously misjumpered, then start hunting for a
> real DEC external CD drive.

Plextors are said to work good, although I sometimes have trouble with them,
too. The key parameter is the block size of the drive. To work on VAXen (and
many other workstations) as boot drives, they must use a block size of 512
bytes. CDROM drives usually have 2048 bytes as default blocksize, and this is
incompatible with most boot monitors. Older Toshiba drives had to be
modified on their PCB to support 512 bytes block size. Plextors, Sony's
and possibly others have a jumber (labeled BLK or similar) which can be
used to switch the block size to 512 bytes.

But even with the correct blocksize, some CDROMs work and some others don't,
so you're best off with a drive which is labeled by the same workstation
vendor. Older RS/6000's are known to be especially picky with respect to
their boot CDROMs. I had a hell of a time trying to install AIX on my RS/6000
Model 320 and I had to resort to an original IBM drive to be successful.

If you have a spare external SCSI harddisk, you can make a blockwise copy of
the CD to the disk (using dd under unix) and boot from that. Hard disks
(almost always) have a block size of 512 bytes and VMS installs just fine from
a hard drive with the image of a VMS installation CD on it.

Good luck,

                                       finger for details
Received on Wed Jun 27 2001 - 13:17:30 BST

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