What was the world's first microprocessor?


Like a lot of other "firsts" in the computer industry, there are a lot of conflicting claims. If you search the web you will find many sites that flatly say the Intel 4004 was the first microprocessor. But interestingly enough, Intel does not say that. Their claim is now somewhat ambiguous, but sometime back in 2009 they simply said that it was"Intel's first microprocessor."


So, what was the first microprocessor?

The Four-Phase Systems AL1 was an 8-bit bit CPU slice containing eight registers and an ALU. It was designed by a team headed by Lee Boysel in 1969. It was not sold as a separate part. Rather it was sold in a complete system with three AL1s forming a24-bit CPUin the Four-Phase System IV/70. It was later officially declared to be a microprocessor in a court case. Texas Instruments sued Intel, trying to invalidate Intel's patent claiming the 4004 was the first microprocessor chip. A demonstration computer system was built with a single AL1, together with RAM, ROM, and an input-output device. A short video on this topic is available on the Computer History Museum web site. An exhaustive discussion of these events can be found in a PhD dissertation by Robert R. Schaller.

The Intel 4004 is recognized today as the first microprocessor sold as a separate electronic component.

For further details and references, see this Wikipedia article aboutmicroprocessorsand this article about theIntel 4004.

The AL4 chips shown on the right in the Four-Phase CPU card image are a remasked version of the original AL1 chips.


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