Category: <b>DOS kernel</b>
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<pre><b>INT 21 - MS-DOS 7 - DRIVE LOCKING AND FLUSHING</b>

	AH = 73h
	DL = drive (0=current, 1=A:, etc.)
	CL = which flag to get or set
	    00h drive flag???
	    01h drive's dirty-buffers flag
	AL = subfunction
	    00h get indicated flag
	    01h set ???
		CH = new value for indicated flag
		    bit 1: ??? (CL=00h only)
		    bit 3: dirty buffers exist for selected drive (CL=01h only)
Return: CF clear if successful
	    for AL=00h:
		AL = value of CL on entry
		for CL=00h: AH = new flag and 06h (i.e. bits 1 and 2 used)
		for CL=01h: AH = new flag and 08h (i.e. bit 3 used)
		(flag being taken from a table of bytes)
	CF set on error
	    AX = error code (01h,0Fh,etc.) (see <a href=../../it/80/16.html>#01680</a>)
		7300h if function not supported
Note:	these two subfunctions are available even when only the MS-DOS kernel
	  is running
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