[Coco] No Nitr(OS-9) in this coco

[Diego Barizo]

For about a month or so, I didn't use any OS-9 disk, but when earlier 
this week I went to try a few games, I found that most disks will fail 
in the boot process, including my custom Nitros-9 disks . This fail 
after the usual i2xo and then repeats KREL until the screen is filled.
But when I tried that same disk in a PC running DK's emu, reading the 
real disk from a 1.2 MB drive, all worked out perfect.
BASIC disks work also 100% OK on the real coco that refuses to load OS-9.
In conclusion... the disk is OK because it works with the PC emulator.
And the drive/controller is OK because it works with any non-OS-9 disk 
(including games like Ghana Bwana that don't use the standard BASIC format)

Any clues?

Diego