[Coco] OS9 vs RSDOS disks

[Robert Gault]

Bill Pierce wrote:
>
> Hi guys,
> Is there a simple way to tell an OS9 disk from an RSDOS disk? Maybe something constant in LSN0 on the OS9 disk?
> It would be nice to identify the disks through software
>
> Thanks
>
> Bill Pierce

Bill,

Unfortunately there is no sure fire method. What might work most of the time is 
to see if there is a root directory in the correct location. If there is, then 
the disk is at least formatted for OS-9 but might also be formatted for Disk Basic.

LSN0 bytes $08, $09, $0A are DD.DIR - address of starting sector of root directory

DD.DIR bytes $10, $11, $12 - indicate address of first sector of directory listing

First sector of listing for any directory

bytes
$00   $2E $AE
$20   $AE
These are the .. and . entries in any OS-9 directory but they are never printed 
by the command dir.

Robert