The Amiga's CPU

The VISCorp[?] Amiga uses a family of Motorola CPUs (Central Processing Unit): The 680x0 range.

Motorola designed the first 68000 from scratch as a 16/32-bit processor. Internally, it was 32-bits, externally: 16-bits.
It can address 16Mb of memory (RAM) and executes just under 1 Million Instructions/Second (MIPS) when running with an 8Mhz clock.
But with this chip Motorola did not want incompatibility problems in the future and completely ceased production of the popular, previously developed 8-bit 6800.

The 68008 was a special low cost version of the 68000 chip. It was used in the Sinclair QL computer, and although it is referred to as a 16-bit CPU, technically it's only 8-bit as it has an 8-bit data bus.

The 68010 was a special version of the 68000 chip designed to work in multitasking environments where the processor pretended to be lots of processors (each program running thinks it's running on its own 68000 chip). Also slightly faster than the 68000 chip, with some complex instructions such as multiply and divide sped up considerably.

The Amiga A1200 uses an 68020 processor with is a full 32-bit version of the 68000 chip running at about 14MHz. The EC version can only address 16Mb of RAM, but the full 68020 chip can address 4 Gigabytes. (EC stands for Embedded Controller, a special cheaper version of the chip designed to be used in video recorders and washing machines!)
The 68020 has, in addition to the registers, another chunk of ultra fast RAM built into it called "cache" which enables the processor to work much faster in certain circumstances.

The 68030 was an upgraded 68020, and contains a memory management unit (MMU). (Although the Amiga A4000/030 model omits the MMU). MMUs are used for many things: on Amigas they can provide virtual memory; where a chunk of the hard disk can pretend to be RAM.

The 68040 comes with an MMU, improves caches, and features a built in Floating Point Maths unit (FPU). This is found in an Amiga A4000/040.

The 68060, is the latest and last in the 680x0 family. This is an ultra fast processor, 100 times faster than the 68000 and three times the performance of the 68040.
It has two MMUs and many other features like: a fully static design - meaning that when individual parts of the processor aren't in use, they do not draw power, making it ideal for portable computers which run off batteries.

Today, Motorola are still manufacturing their microprocessor: 68020 (for standard Amiga A1200s) and 68030, 68040 and 68060 for accelerator manufacturers such as: Phase 5's Blizzard developments.
Motorola are also currently planning a PowerPC Amiga. For the report please click here.

About speeds of CPUs: The speed of the chip is not judged by its name,
i.e.: A type of 68030 can run at 25MHz and another type can run at 50MHz.

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