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Date:	Sun, 3 Mar 2002 10:39:51 PST7
From:	Steve Carter <scarter@vcnet.com >
Reply-To:	scoug-help@scoug.com
To:	scoug-help@scoug.com
Subject:	SCOUG-Help: boot scsi cd

Content Type: text/plain

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On 3/3/02, Sandy Shapiro wrote, in part:
>========================================
>>One can boot from a SCSI CD-ROM drive just as
>>easily as from an ATAPI CD-ROM. But only newer
>>machines can boot from CD-ROM. This is because
>>you must have CD-ROM boot support in your BIOS.
>>
>>In this case, it must be in the SCSI BIOS.
>>If you're using a simple 53C810-based fast SCSI II
>>card, then there is no SCSI BIOS ...
>
>My SCSI adapter card has no BIOS.
>The motherboard is quite new and the [MB] BIOS
>supports SCSI boot selection.

That means boot from SCSI HD instead of IDE HD
-- it's a boot order issue if you have both.

All it does is suppress normal booting from an
IDE HD if a SCSI Host Adapter (HA) and SCSI boot drive
are present. The HA must still have a SCSI BIOS
to boot ANYTHING on the SCSI bus.

>It is just that none of the motherboard settings
>seem to recognize a CD in the [SCSI CD-ROM] drive.

They won't, without software/firmware to talk to the
devices. With ATAPI CD-ROM drives, some simple support
is now normally a part of the MB BIOS. But the MB BIOS
doesn't normally include a SCSI BIOS, necessary to talk
to SCSI devices on the SCSI bus.

In that case, the device drivers must be loaded by
the OS after the Host Adapter driver is loaded.
These drivers you load into the OS then assume
the functions from the SCSI BIOS. If there is
no SCSI BIOS, then you MUST WAIT until the
drivers are loaded to communicate with the
devices on the SCSI Bus.

>Does that mean that the SCSI adapter card must
>have a BIOS for booting to work?

Exactly. That's what a SCSI BIOS is for.
Your MB BIOS recognizes only IDE controllers and drives,
Without additional firmware incorporated into the
MB BIOS, it does NOT recognize SCSI Host Adapters
(and the devices attached).

HAs are all a bit different, and require their own
custom BIOSes to boot, and this includes booting from
a CD-ROM, a feature only recently incorporated
into PCs (OK, it's been several years now).

Bottom line:
------------
You cannot boot from a SCSI device unless there
is BIOS support for it. This almost always means
SCSI BIOS support. No SCSI BIOS, no booting from
SCSI.

Other SCSI stuff (scanners, tape drives, etc.) work
fine AFTER you've loaded the drivers into the OS.

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