Raster bar

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The raster bar (also referred to as rasterbar or copperbar) is an effect used in demos and older video games that displays animated bars of colour, usually horizontal, which additionally might extend into the border, a.k.a. the otherwise unalterable area (assuming no overscan) of the display. Raster bar-style effects were common on the Atari 2600 and Atari 8-bit computers (because they could be easily displayed using the hardware of those systems) and then later in demos for the Commodore 64, Amiga, Atari ST, and Amstrad CPC.

The term copperbar comes from a graphics coprocessor on the Amiga home computer referred to as the Copper (a shortened form of coprocessor). It can be programmed to change the display colors per scan line without requiring the CPU, except to update the position of the bars once per frame.