More top-post alert! :-)
IIRC I had burned the Ultrix CD "normally" (means without fiddling with
block size, so not 512), but changed the block size to 512 for booting
it. IIRC #2, burning was done on another drive, not the Plextor.
regards,
chris
On 5/20/21 11:26 PM, Jonathan Stone wrote:
 [[ apologies for top-post: Y! issue ]]
 I know that to be bootable on DECstation/VAX/early Alpha, CD-ROMs
 needs to be jumpered to 512-byte blocks. Like RRD4x.
 Does the burning CD write need to be jumpered to 512-bytes? Or can one
 write on a "normal" CD burner, then read on a 512-byte-block CD-ROM ?
 If the former, I guess I'll have to find an old, 512-byte-block
 jumperable SCSI CD burner.
 On Thursday, May 20, 2021, 02:15:39 PM PDT, Christian Groessler via
 cctalk <cctalk at classiccmp.org> wrote:
 On 5/20/21 11:05 PM, Jonathan Stone via cctalk wrote:
 ? MacOS (Mojave) can mount an image read from a
512-byte UFS CD.
 What does one have to do (Linux, MacOS, *BSD) to write such an image  
 to the CD
with 512-byte blocks, so it can be read by a DEC boot-ROM?
 I think that's a property of the CD drive, not the disk itself.
 I've got a Plextor CD writer which can be jumpered between 2048 and 512
 byte blocks.
 I was able to boot the Ultrix installation CD (MIPS) on a DECServer.
 regards,
 chris