Editing Amiga (section)

=== Central processing unit ===
The most popular models from Commodore, including the [[Amiga 1000]], [[Amiga 500]], and [[Amiga 2000]], use the [[Motorola 68000]] as the CPU. From a developer's point of view, the 68000 provides a full suite of [[32-bit]] operations, but the chip can address only 16&nbsp;MB of physical memory and is implemented using a 16-bit [[arithmetic logic unit]] and has a 16-bit external [[data bus]], so 32-bit computations are transparently handled as multiple 16-bit values at a performance cost.<ref name="AutoP5-4" /><ref name="AutoP5-5" /> The later [[Amiga 2500]] and the [[Amiga 3000]] models use fully 32-bit, 68000-compatible processors from Motorola with improved performance and larger addressing capability.

CPU upgrades were offered by both Commodore and third-party manufacturers. Most Amiga models can be upgraded either by direct CPU replacement or through expansion boards. Such boards often included faster and higher capacity memory interfaces and [[hard disk]] controllers.

Towards the end of Commodore's time in charge of Amiga development, there were suggestions that Commodore intended to move away from the 68000 series to higher performance [[RISC]] processors, such as the [[PA-RISC]].<ref name="actuator" /><ref name="Haynie" /> Those ideas were never developed before Commodore filed for bankruptcy. Despite this, third-party manufacturers designed upgrades featuring a combination of 68000 series and PowerPC processors along with a PowerPC native [[microkernel]] and software.<ref name="AutoP5-6" /><ref name="AutoP5-7" /> Later Amiga clones featured [[PowerPC]] processors only.