Editing Amiga Original Chip Set (section)

====Uses of the Copper====
* The Copper is most commonly used to set and reset the video hardware registers at the beginning of each frame.
* It can be used to change video settings mid-frame. This allows the Amiga to change video configuration, including resolution, between [[scanline]]s. This allows the Amiga to display different horizontal resolutions, different color depths, and entirely different frame buffers on the same screen. The [[AmigaOS]] graphical user interface allows two or more programs to operate at different resolutions in different buffers, while all are visible on the screen simultaneously. A paint program might use this feature to allow users to draw directly on a low resolution [[Hold-And-Modify]] (HAM) screen, while offering a high resolution toolbar at the top or bottom of the screen.
* The Copper can also change color registers mid-frame, creating the "[[raster bar]]s" effect seen commonly in Amiga games. The Copper can go further than this and change the background color often enough to make a blocky graphics display without using any bitmap graphics at all.
* The Copper allows "re-use" of sprites; after a sprite has been drawn at its programmed location, the Copper can then immediately move it to a new location and it will be drawn again, even on the same scanline.
* The Copper can trigger an interrupt when the video beam reaches a precise location on the display. This is useful for synchronizing the CPU to the video beam.
* The Copper can also be used to program and operate the blitter. This allows blitter operation and control to proceed independently of, and concurrently with, the CPU. With copper and blitter programming each other a text mode can be emulated.
* The Copper can be used to produce "sliced [[Hold-And-Modify|HAM]]", or S-HAM,<ref>Invented in 1989 by Rhett Anderson {{cite web |url=http://www.islandnet.com/~kpolsson/amigahis/amig1989.htm |title=Chronology of Amiga Computers (1989) |access-date=2006-07-10 |url-status=dead |archive-url=https://web.archive.org/web/20060710012217/http://www.islandnet.com/~kpolsson/amigahis/amig1989.htm |archive-date=2006-07-10 }}</ref> this consists of building a Copper list that switches the palette on every scanline, improving the choice of base colors in [[Hold-And-Modify]] mode graphics.