Steve Gray started a new project. He uses an 80 column (monochrome) CBM/PET to display a 40 column screen with colour. A normal 80 column CBM/PET uses two RAM banks for the text. Steve now uses one RAM bank for the text (40 columns) and the other RAM bank for the colour information. You can read all the details on his web page.
Source: http://www.richardlagendijk.nl