There is a cool demo trick to raise the apparent resolution for scrolling 80 column text. Alternate between two 80 column displays each of which have 4 pixel c

There is a cool demo trick to raise the apparent resolution for scrolling 80 column text. Alternate between two 80 column displays each of which have 4 pixel columns per character as matches the hardware resolution. On even frames display the even number columns of an 8 column character set; on odd frames display the odd columns. Without a scroll, that gives a flickering halftone image between the two halves of the character images. Old CRT's had slow phosphors so the flickering isn't so bad there, but still it doesn't give truly higher resolution. Now introduce a one pixel per every two frames horizontal scroll. Your eyes track the moving text smoothly. Relative to that moving frame of reference, the odd frames are positioned half a pixel to the right of the corresponding even frames. So in that moving frame of reference you have a "true" interlaced 640 pixel column high resolution display.