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

	AH = 1Dh
Return: AL = 00h
Note:	corresponds to the CP/M BDOS function "get bit map of read-only
	  drives", which is meaningless under MS-DOS
SeeAlso: AH=18h,AH=1Eh,AH=20h,AX=4459h
</pre>