INT 10 - VIDEO - PCjr - MANIPULATE CRT/CPU PAGE REGISTERS
AH = 05h
AL = subfunction
80h read CRT and CPU page registers
Return: BH = CRT page register
BL = CPU page register
81h set CPU page register
BL = CPU page
82h set CRT page register
BH = CRT page
83h set both CPU and CRT page registers
BL = CPU page
BH = CRT page
Notes:  the CPU page determines which 16K block of the first 128K of physical
memory will be mapped at B800h by the hardware
the CRT page determines the start address of the memory used by the
video controller


1005 - VIDEO - PCjr - MANIPULATE CRT/CPU PAGE REGISTERS