160x160 pixels? 
Can someone explain the 160x160 graphic mode in more detail? If the machine normally used 23 lines of text with an 8x8 pixel matrix, that would give 23*8=184 pixels of height. Double-height characters would imply half of that, i.e. 92 pixels.  The 200 characters mentioned is enough for  a square-shaped array of 14x14 characters. 14*8 = 112.   Since 92 != 112 != 160 I am confused -)