[Oberon] FPGA - System Crash

[Andreas Pirklbauer]

   > Yes, true. This where the boot fails, also Oberon-0 never gets to
   > the command loop, as it fails on a corrupt file system.
   > 
   > Could it also fail on blank card?
   >

Well, if the file data itself has been corrupted, one can use the tools
‘DiskCheck' and ‘Scavenger’. But the Oberon-0 command interpreter
should not fail to execute even if the disk is corrupt.

I may add ‘DiskCheck' and ‘Scavenger' to the system building tools if
there is demand for that. But I didn’t see the need for that because with
SD cards is easy to make a backup of an entire SD card - so THAT is
your recovery tool --> just make regular backups...

PS: If you are familiar with the way B-trees work, you can build
those tools yourself. It would make for a nice student exercise.
They are just variations, or rather, extensions of Oberon-0:

1. DiskCheck essentially adds a "directory traversal” command
    which lists faulty directory sectors

2. Scavenger essentially adds a command to scan the entire
    disk and gradually builds up a new directory. This allows
    one to recover files that are no longer accessible from
    the directory.

-ap