Int 10 Fn 1103  - Video - Text-mode Chargen - Set Block Specifier (ps,ega  [V]

   AX = 1103h
   BL = block specifier (see #0019)

Return: nothing

Notes: (see also AX=1110h)
   This function allows dual character sets to appear on screen
     simultaneously

See Also: AX=1100h,AX=1101h,AX=1102h,AX=1104h,AH=1Bh,AX=CD10h

Bitfields for block specifier:
Bit(s) Description (Table 0019)
---EGA/MCGA---
 0,1   block selected by characters with attribute bit 3 clear
 2,3   block selected by characters with attribute bit 3 set
---VGA---
 0,1,4 block selected by characters with attribute bit 3 clear
 2,3,5 block selected by characters with attribute bit 3 set