[Coco] Nitros9 & Mess

[Robert Gault]

Nathan Woods wrote:

><snip>
> Then again, it is always possible that I was chasing phantoms.  I seem 
> to have lost my notes from last September; Robert Gault, do you remember 
> anything?
><snip>

Here are some details I observed with the directory corruption problem.

1) The problem varies with the version of OS-9 running but only with 
emulation. I have only heard of this reported for MESS but it is 
possible that other emulators have problems. The most recent versions 
from Boisy have the most problems.

2) The corruption occurs with programs that edit files by opening a temp 
file, deleting the original, and renaming the temp to the original. 
Using the exact same .dsk image and Build or copy, a new file can be 
created in a directory without corruption.

3) The directory corruption is as follows: The first sector of the 
directory listing is copied over the second sector of the listing 
resulting in duplicate . and .. entries (along with other files.) It is 
the circular nature of the duplicate . .. entries that drives OS-9 crazy.

4) The problem may require that the first sector be filled. The problem 
does not occur when editing a directory which has a single file.

As for the rest of the MESS debugger results, they seem to indicate that 
the wrong block of RAM is being processed during the editing of the 
directory structure. I can't quite remember whether the corruption 
occurs before and editor like Scred exits or while the edit is in 
progress. I think it is necessary to exit the program but that should be 
rechecked.

I have thought that some obscure timing in emulation is at the root of 
the problem but that is a guess.