Abstract: A decoder apparatus (200) provides an R,G,B,I video drive signal in a TTL type of format from a received composite video input signal which comprises sync information and displayable information, such as conventional black and white video or a digitally encoded color video signal comprising a sixteen level code for providing sixteen possible color combinations of R,G,B, and I, without loss of bandwidth. The decoder (200) includes means for receiving the composite video input signal (202,10) and restoring it into separate DC restored sync (20a, 20b) and black and white or color video display information (30, 40, 50), both of which may be displayed on the same RGB monitor (107). White reference level signals are dynamically provided from the sampled video information and are used by a flash converter (100) in converting grey scale digitally encoded color video information into the TTL format R,G,B,I type of video signal (60, 70, 80a, 80b, 82a, 82b, 82c) which recovers the origianl R,G,B,I color signal.

Abstract: An encoder (500) encodes a TTL type of R,G,B,I video drive signal into a common multilevel grey scale digitally encoded composite video signal which is transmitted over a single coaxial cable (302). The incoming R,G,B,I bits, such as provided from a color computer (304, 306, 308, 310), are buffered and translated (50a, 50b) from TTL to ECL and fed to a common video digital-to-analog converter (100) along with translated composite sync information (312, 314, 10, 324). A white reference level signal is dynamically derived from the translated sync information (200, 202) and provided to the full height input of the video D/A converter (324, 100) which converts the translated R,G,B,I input into a 16 level multibit grey scale code in a linear function from full intensity white to black, with a seventeenth level being provided in the digitally encoded composite video signal to represent sync information.