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Will We Ever Really Know Who Invented the Microprocessor?

 

FPGA luminary David Laws has just published a well-researched blog on the Computer History Museum’s Web site titled “Who invented the Microprocessor?” If you’re wildly waving your raised hand right now, going “Ooo, Ooo, Ooo, Call on me!” to get teacher’s attention because you think you know the answer, then you don’t understand that it’s a trick question. It all depends on how you define the word “microprocessor,” doesn’t it?

According to Laws, there is no lack of good candidates:

Four Phase Systems 8-bit AL1, first demonstrated in working systems in April 1969. (Industry gadabout and processor expert Nick Treddenick’s pick.)

Ray Holt’s 20-bit MP944 custom chip set, developed for Garrett AiResearch’s Central Air Data Computer for use in the F-14 Tomcat fighter jet’s flight-control system, and first manufactured in 1970. (Note: This was not a single-chip microprocessor, but it was a microprocessor by some definitions.)

Intel’s 4-bit 4004, originally developed in early 1971 as an implementation mechanism for Busicom’s line of calculators and first advertised as a commercial microprocessor in November, 1971.

Intel’s 8-bit 8008, originally developed for the CTC/Datapoint 2200 Programmable Terminal and delivered in late 1971.

TI’s 8-bit TMX1795, another implementation of the CTC/Datapoint 2200 Programmable Terminal processor, delivered to CTC a few months before Intel’s 8008, but with a design bug caused by an error in the original processor definition.

So there you have it; it’s a trick question. Do you include multi-chip processors? If so then the MP944 is your pick. If it has to be a single-chip processor but need not have been sold as a commercial chip on the open market, then the AL1 might be your choice. If a calculator processor that ended up opening the era of embedded system design qualifies, then the Intel 4004 is your answer. If a “real”-but-flawed, single-chip processor that didn’t meet the customer’s intended spec qualifies, then TI will get your nod. If none of these, then you’re an Intel 8008 booster.

This is not merely an academic exercise. There has been plenty of patent litigation attached to the answer to this question.

I’ve been dancing on the head of this pin a long time as an editor and industry historian. For my money, the first commercially successful microprocessor, the one first sold on the open market to design engineers, is Intel’s 4004.

You can put your hands down now. Class is no longer in session.

 

 

One thought on “Will We Ever Really Know Who Invented the Microprocessor?”

  1. Steve, Your logic of elimination of 1st microprocessors was going well until you hit your own roadblock. You see in those days there were no solid definition of a microprocessor; single-chip, LSI, Integrated Circuit, commercial, military, chip set … it was really nothing. We all were looking for something that worked a practical function. Paper designs were everywhere, one chip here and two chips there, CPU’s bit slices, multi-chip solutions were a thought. Now really only two chips sets really worked.

    1970 MP944 worked in a flying airplane for the US Navy. P-channel. Military spec. 20-bit
    1972 4004 series (6 chips + 59 TTL) worked in a desktop calculator, P-channel. Commercial. 4-bit

    It’s is really a very big technical NO BRAINER. The MP944 was the first working microprocessor with no competition. Almost 30 years of flying as the premier fightjet with no microprocessor issues.

    NOW, you and others, start getting it messy when you think marketing has to do with what makes it first. The 4004 is not single-chip. Intel was going to drop the whole project because it was not selling. I was hired with two others, Manny Lemas, Gary Kildahl, to teach engineers to program and after about two years RCA joined the programming microprocessor solution and kicked off the market.

    In the meantime the secret MP944 was defending our country without a glitch. Dual redundcy, 20-bit, in-flight self-test, coprocessors, parallel processing, and much more not used until much much later.

    Ray Holt
    Designer MP944
    Intel Consultant to teach programming of the 4004

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