[Coco] Nitros9 Boot Process

[Tormod Volden]

On Tue, Jan 15, 2019 at 2:06 PM Walter wrote:
>
> Thanks.
>
> That makes sense for a boot from a floppy connected directly from the system.
>
> How does HDB-DOS and DW4 change that?
>
> When the vhd contains a number of preliminary floppies and then a hard drive HDB-DOS must load the kernel file from track 34 of the nominated floppy.  But the bootfile must reside where? The floppy or the hard drive.

Where the bootfile must be located fully depends on the
device-specific boot module that has been embedded in the kernel file.

In your case I guess that means the hard drive part of the vhd.

Also, the combined HDB-DOS/NitrOS-9 disk images that I have seen have
the NitrOS-9 partition first, followed by the floppy images. So
HDB-DOS adds the "HDB-DOS offset" to find the floppies, whereas the
boot module and the booted NitrOS-9 won't need any sector
recalculation.

>
> Is it possible to mount the virtual floppies that precede the harddrive in a VHD so that they can be accessed from Nitros9 via DW?
>
> If not the build process for creating a bootable VHD image must be via an external tool!

You can also boot NitrOS-9 without going through floppy images. The
DriveWire disk images on the NitrOS-9 site only have a NitrOS-9 (RBF)
filesystem and no floppies. If you run DWDOS (available as DECB binary
or ROM images) it will load the kernel file from track 34 of the disk
image.

Regards,
Tormod