[Coco] FHL Color Flex

[Frank Swygert]

So track 0 is different, believed to be single density.  That can cause 
problems for creating an emulator DSK image file. So WHY is track 0 SD, 
and what part of the code reads/uses it? The solution may be to solve 
that riddle and modify the code so that it no longer needs the SD track. 
I suspect it's a boot program of some kind. FLEX (like OS-9) was likely 
developed on an old system that used SD disks as standard, then when DD 
disks became the norm everything was changed except the boot track. That 
would allow an old system to start then give an on-screen error as to 
why it stopped, and a newer system (since the controller of the day 
could read SD and DD) would boot as well. The boot loader that diverts 
to drive 0 track 16 sector 9 may have code pointing back to the SD 
track. Of course the SD track may be blank formatted and the check for 
track 0 as SD may just be a simple form of copy protection. Come to 
think of it, that's the more likely case since it's hard to format one 
track SD and the rest DD.