[Coco] Booting NitrOS9 from Drive 1

[Robert Gault]

Fred D. Provoncha wrote:

> Hello everyone,
> 
> Here's a pretty simple question that I'm sure several of you may be able 
> to answer. What do I need to do to get configure a boot disk so that it 
> will successfully boot NitrOS9 from Drive 1 of a 2-drive Coco system? I 
> can create boot disks that boot from Drive 0 but none of them of course 
> can boot when put into Drive 1. I type in DOS1, Drive 1's light comes on 
> for a second, goes out, and then Drive0's light comes on and waits for 
> me to insert a boot disk into Drive 0.
> 
> I think I have it narrowed down to the boot module that is installed on 
> the boot track during the process of creating the boot disk. The boot 
> module I'm using is boot_1773_6ms, which comes with the standard NitrOS9 
> distribution. It looks like that module is configured to search for the 
> OS9Boot file in Drive 0. How do I change that?
> 

If you want to create NitrOS-9 from the source code, it is simple. Look 
at the file Level1\modules\boot_1773.asm and you will see
* Default Boot is from drive 0
BootDr   set DRVSEL0
          IFEQ  DNum-1
BootDr   set DRVSEL1		Alternate boot from drive 1
          ENDC
          IFEQ  DNum-2
BootDr   set DRVSEL2		Alternate boot from drive 2
          ENDC
          IFEQ  DNum-3
BootDr   set SIDESEL		Alternate boot from drive 3
          ENDC

These alternate boot modules are not part of the distribution. However, 
it looks as though you can change the last byte in the newest version of 
the module before the CRC, verify the module, and boot from the kernel 
from the desired drive. You would also have to change init or /dd or the 
boot will still be split between two drives.