INT 10 - VIDEO - TEXT-MODE CHARGEN - SET BLOCK SPECIFIER (PS,EGA,VGA)

	AX = 1103h
	BL = block specifier (see #00020)
Return: nothing
Notes:	(see also AX=1110h)
	This function allows dual character sets to appear on screen
	  simultaneously
SeeAlso: AX=1100h,AX=1101h,AX=1102h,AX=1104h,AH=1Bh,AX=CD10h
SeeAlso: MEM 0040h:0084h
Index:	text mode;font|text mode;screen rows