CGA As You Have Never Seen It Before

An old-style graphics system as found on many 8-bit computers and on early PC graphics cards drew its characters by retrieving their bitmaps from a ROM. With a little sideways thinking, [GloriousCow] has exploited this process to make a CGA card perform graphical tricks it was never designed to do. The CGA card clocks its character ROM continuously across the whole screen, even at the edges where nothing would normally be displayed.