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AGA was originally called '''AA''' for '''Advanced Architecture''' in the United States. The name was later changed to AGA for the European market to reflect that it largely improved the graphical subsystem, and to avoid trademark issues.<ref>{{Cite web|url=http://www.amigahistory.co.uk/amigaaga.html|title=Amiga History Guide|website=Amiga History}}</ref>
AGA is able to display graphics modes with a depth of up to {{nowrap|8 bit}}s per pixel. This allows for {{nowrap|256 colors}} in indexed display modes and {{nowrap|262,144 colors}} (18-bit) in [[Hold-And-Modify]] (HAM-8) modes. The palette for the AGA chipset has 256 entries from {{nowrap|16,777,216 colors}} (24-bit) in every possible resolutions, whereas previous chipsets, the [[Original Chip Set]] (OCS) and [[Amiga Enhanced Chip Set|Enhanced Chip Set]] (ECS), only allow {{nowrap|32 colors}} out of 4096 or 64 colors in Amiga [[Extra Half-Brite]] (EHB mode) only in lower resolution and lowered to 16 or even 4 colours in higher resolutions. Other features added to AGA over ECS are super-hi-res smooth scrolling and 32-bit fast page memory fetches to supply the graphics data bandwidth for 8 bitplane graphics modes and wider [[Sprites (computer graphics)|sprites]].
AGA is an incremental upgrade, rather than the dramatic upgrade of the other chipset that Commodore had begun in 1988, the [[Amiga Advanced Architecture chipset]] (AAA), lacking many features that would have made it competitive with other graphic chipsets of its time. Apart from the graphics data fetches, AGA still operates on 16-bit data only, meaning that a lot of bandwidth is wasted during register accesses and [[Original Chip Set#Copper|copper]] and [[blitter]] operations. Also the lack of a [[packed pixel|chunky]] graphics mode is a speed impediment to graphics operations not tailored for [[Planar (computer graphics)|planar]] modes, resulting in ghost artifacts during the common productivity task of [[scrolling]]. In practice, the AGA HAM mode is mainly useful in painting programs, picture viewers, and for video playback. Workbench in 256 colors is much slower than [[Amiga Enhanced Chip Set|ECS]] operation modes for normal application use; a workaround is to use multiple screens with different color depths.
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