Category: <b>memory management</b>
<br>Flags: Undocumented function<p>
<pre><b>INT 2F - HIMEM.SYS v2.77+ - GET A20 HANDLER NUMBER</b>

	AX = 4308h
Return: AL = 43h if supported
	    BL = A20 handler number (value of /MACHINE:nn switch)
	    BH = AT A20 switch time (00h medium, 01h fast, 02h slow)
Note:	if the A20 handler number returned in BL is 00h, an external handler
	  is being used (see AX=4330h)
SeeAlso: AX=4309h,AX=4330h
</pre>