AB9 Pro Motherboard SATA/AHCI installation problem

[Chris G]

As I reported here earlier I have installed Fedora 7 on my system with
a view to replacing Slackware.   In an effort to try and sort out the
problems with Fedora 7 stopping I decided to upgrade the BIOS.  I have
installed the version 21 BIOS for the AB9 Pro and it has caused a very
odd problem...

After upgrading the BIOS Fedora wouldn't boot any more, it loaded the
kernel and then fell in a crumpled heap unable to see the disks.  I
thought this might be because the SATA interface needed to be switched
to AHCI mode but on doing this the disks are no longer visible at all at
boot time so the system refuses to even start booting.

So I have set the SATA disks back to IDE mode, and noticed that my old
Slackware installation still boots (using the grub loader installed by
Fedora!).  Why does my Slackware still boot when Fedora can't seem to
see the disks at all?

-- 
Chris Green