INT 15 - DOS/V - FONT SUBSYSTEM ACCESS                                          
	AH = 50h
	AL = which function address to retrieve
	    00h "read font" function
	    01h "write font" function
	BL = 00h
	BH = character size (00h single-byte, 01h double-byte)
	DH = width of character cell
	DL = height of character cell
	BP = code page (see #00470)
Return: CF clear if successful
	    AH = 00h
	    ES:BX -> requested function's address
	CF set on error
	    AH = error code (see #00471)
SeeAlso: AH=49h


(Table 00470)
Values for DOS/V code page:
 0	default
 437	US English
 932	Japanese
 934	Korea
 936	China
 938	Taiwan
SeeAlso: #01757


(Table 00471)
Values for DOS/V error code:
 01h	invalid font type in BH
 02h	BL not zero
 03h	invalid font size
 04h	invalid code page
 80h	unsupported function (PCIBM PC)
 86h	unsupported function (XTIBM PC XT)
SeeAlso: #01680