Michael:
A quick test would be to pad the cdhdtape image to a multiple of 18K, burn that adjusted image, and see if it works:dd if=cdhdtape of=/tmp/cdhdtape bs=18k conv=syncThat was a promising idea Michael. Executing that command produced a file 3778560 bytes in size. I burnt it to CD and tried to boot the PWS but the "block size is not 512 bytes" error occurred and the boot failed the same as usual.That sounds like the problem of your CD drive using 2048 byte blocks, and the SRM on the PWS probably has to have 512 byte blocks.
It does sound like that but the BLOCK jumper on the CD drive was in place at the time.
% dd if=/dev/zero of=2048b bs=512 count=4 4+0 records in 4+0 records out 2048 bytes transferred in 0.001 secs (2048000 bytes/sec) % ls -l 2048b -rw------- 1 ray wheel 2048 Jun 5 10:18 2048b % cat 2048b >> cdhdtape % ls -l cdhdtape -rw------- 1 ray wheel 3778560 Jun 5 10:19 cdhdtape %but apparently that idea was way off track. When I tried to boot the PWS using it the screen went blank and the machine rebooted as though it had been power-cycled.Hmm, that should have created the same image as my dd command - you could compare the two files to see if there was any difference.
I'd deleted the files I'd been experimenting with so couldn't check them, but I tried creating the padded cdhdtape file again using both techniques and both resulting files did have the same md5 value. So, I don't know what happened with my previous attempt. I burnt one of the padded cdhdtape files onto CD and tried booting the PWS using the Plextor SCSI drive. It didn't say "block size is not 512 bytes" but the boot failed with the normal text errors.
I think the SRM on my CS20 can deal with the CD drive having 2048 byte blocks, and will do the buffering and addressing of 512 bytes when using the SRM read routine. I just successfully booted my CD created as above on my CS20.
Fortunately, I also tried the same CD in the IDE CD drive from the XP1000 because it then did boot the PWS successfully (and also the XP1000 when I tried it there). It also worked when I tried it in a generic Sony IDE CD drive, so the Plextor drive must have a subtle problem. :(
Fortunately I've been able to use CD-R/W media to minimize wastage. I've just used a couple of CD-Rs to ensure that wasn't a factor.I'm not sure the CD drive in my CS20 would work with a CD-R/W. I know the old DEC drives that came with the vax, decstatsion, and early alphas didn't seem capable of reading CD-R/W media.
I don't know much at all about the CS20--what vintage are they? The only original CD drives I've come across in my limited experience with Alphas which can read CD-R/W media were in an ES40 and an XP1000, relatively recent machines.
Thanks a lot for solving this problem. Would you like me to send a PR about it?
Ray