Function 0Ch    Write Dot - plot one graphics pixel 

entry   AH      0Ch 

	AL      dot color code  (0/1 in mode 6, 0-3 in modes 4 and 5) 

		(set bit 7 to XOR the dot with current color) 

		0-3 mode 04h, 05h 

		0-1 mode 06h 

	BH      page number (ignored if adapter supports only one page) 

	CX      column (X=0000h - 027Fh) 

		(0 - 319 in modes 4,5,13,  0 - 639 in modes 6,14,15,16) 

	DX      row    (Y=0000h - 00C7h) (0 - 199 CGA) 

return  none 

note    Video graphics modes 4-6 only 

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