Category: <b>DOS kernel</b>
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<pre><b>INT 21 - DOS 1+ - NULL FUNCTION FOR CP/M COMPATIBILITY</b>

	AH = 18h
Return: AL = 00h
Note:	corresponds to the CP/M BDOS function "get bit map of logged drives",
	  which is meaningless under MS-DOS
SeeAlso: AH=1Dh,AH=1Eh,AH=20h,AX=4459h,INT 60/DI=0513h
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