ADVANCE WARNING (perhaps) for CRASHES
	
	
	The Chipmunk (all CDOS versions, even 3.11) has an occasional crash due
to the main directory being overwritten.  I have been able to mimick this crash
by setting the first byte of the Allocation Table to 0 (it's normally 
240, the code for a directory).  In consequence the next SAVE to disk 
thinks that Cluster 0 is free for filing, and overwrites the directories
 and maybe even the Allocation Table itself.
	The first byte is probably reset (not always to 0, those are just the
 cases that produce catastrophic results) in the RAM image of the allocation
 table which starts at 59589 (at least in v.3.11).  If you'll check that
 location with ?PEEK(59589) after all non-CRC disk errors and report the
 results to Larry Holmes, perhaps it will help find this occasional bug in
 an otherwise lovely operating system.  In the meantime....
	PRECAUTIONS:  Use the procedures in INSURE.DIR regularly for backup in
 case of a crash.  The program PRESAV.BA listed below, however, may well warn
 you of an impending overwrite if you ise it BEFORE EVERY DISK SAVE.  The
 crashes are rare and often discovered only well after the damage has been 
done (if you are working in a subdirectory and don't pop out to the
 main directory for awhile); they may be associated with error messages (my
 recent ones have been heralded by RF errors) but maybe not.
	
	When it's really important, both 1) check before saving to disk with
PRESAV.BA, and immediately afterwards 2) save a new backup of the directory
and alloation table with SAVDIR.BA (from the INSURE.DIR package).
	
1 'PRESAV.BA to test for imminent disk overwrite.  W.H.Calvin 71256,1353 
10 IF LEFT$(DSKI$(0,0,5,0),1)<>CHR$(240)THEN 20
15 CLS:PRINT@90,"Probably OK to SAVE":SOUND9999,10:MENU
20 BEEP:BEEP:CLS:PRINT"Oops, you had a glitch in the":PRINT"Allocation Table"
22 PRINT "The first byte was reset to: ";ASC(LEFT$(DSKI$(0,0,5,0),1))
25 PRINT:PRINT"Make a note of any prior symptoms or" 
27 INPUT" error messages.  ENTER to reset the bad byte";X$:IFX$=""THEN30ELSE STOP
30 A$=DSKI$(0,0,5,0):MID$(A$,1,1)=CHR$(240)
40 DSKO$0,0,5,0,A$:DSKO$ 0,0,6,0,A$:MENU	
	
Again, see DL4's INSURE.DIR (and the patch in INSURE.FIX) for backup and
 restoration procedures following an overwrite.
		William Calvin
		71256,1353
		29 May 1985