🚀 go-pugleaf

I wrote a program which intercepts the Rwabs call through the Rwabs vector at
0x476 and noticed something really strange.  It seems that the operating system
sometimes calls Rwabs with the buffer argument set to zero.  Does this mean
that the operating system will load sectors starting at address zero, writing
over all the interrupt vectors stored at these locations?  If, as I suspect,
it does not, then what specifically does it do?  In all the documentation I
have examined, I have found no mention of Rwabs doing anything special under
these circumstances.

Upon further investigation of this phenomenon, I noticed that it occured only
when a folder was first entered from the desktop.  When I tried changing to
a folder from the Mark Williams shell, this phenomenon did not exhibit itself.
Also, this seems to only happen on the floppy drive; when I set up my routine
to intercept the hard drive, the buffer always seems to contain a valid value,
no matter whether I'm using the desktop or the shell.

I'd appreciate any comments from anyone with any thoughts on this matter.
Allan, you seem to be the authority on the ST's operating system, do you have
any idea what's going on?