Alan D Johnson wrote:

> Ahhh. didn't know that, all the Cxxx that I have dealt with have
> internal CD's so haven't had to deal with it. Must be related to the
> C720 SCSI driver in the 7's, probably the same reason 11.x is
> unsupported on them, right?

I don't know about the C720 SCSI driver but the issue with the 512byte mode
jumper of older 700 series is (like on most other UNIX workstations of that
time) just a firmware issue. The old firmware was only able to boot from
disk devices which generally have 512bytes/sector. A standard ISO CDROM is
2048bytes/sector so the firmware could not handle them. To resolve this some
CDROMs got a jumper to force them to 512byte sector size so that the
firmware sees the CDROM just as another disk device it can use to boot from.

On more modern workstations (from HP it's the Bxxx/Cxxx/Jxxx and when I
remember right also some of the newer 700's) the firmware is able to set the
512 byte mode via a SCSI command. And the somewhat current systems (i.e.
Bxxxx/C3xxx/Jxxxx) alsow boot from 2048byte devices just fine.

BTW: the only UNIX systems that never required a CDROM with 512byte mode
jumper to boot from are the IBM RS/6000's. Even my old 7012-320H (1990
vintage) boots just fine from any generic SCSI CDROM ;-)

Benjamin