INT 10 - VIDEO - PCjr, Tandy 1000 - SET CRT/CPU PAGE REGISTERS

	AH = 05h
	AL = subfunction
	    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
Return: nothing
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
SeeAlso: AX=0580h