This week we celebrate the 35^th anniversary of the Intel 4004 customer programmable microprocessor.  It was the first processor on a chip and was the beginning of the revolution in personal computing, ultimately impacting practically every electronic device made.  Curiously, it was almost by accident that it happened at all.  Intel had no plan to design and build a microprocessor so how did it happen?

Intel was started by two semi conductor engineers, Gordon Moore and Robert Noyce, in 1968. They wanted to use large scale integration to build solid state memory devices.  At the time this was a very novel idea since computers were using magnetic cores as random access memories.  Their first product was a 16 bit, yes 16 bit, memory chip and their vision was to use LSI to build larger and larger arrays of memory chips that would ultimately replace magnetic cores.  The primary advantages of this approach being speed and density.  Hundreds and thousands of storage cells could be built into each chip in the space used by a single magnetic core.  To give you an idea of size, a magnetic core is shaped like a doughnut and is about the size of the tip of a ball point pen.  Each core constituted one bit and three to five wires had to be threaded through each one - a manufacturing challenge to say the least.

About this time the electronic calculator made its appearance using custom integrated circuits coupled with a keypad and small display.  It is hard to imagine today that there was a time in the recent past when there were only desk mechanical calculators or room size computers and nothing in between.    In 1969, Nippon Calculating Machine Corp. asked Intel to design several custom chips for its new Busicom 141-PF printing calculator.  The Intel engineers assigned to the task were Ted Hoff, Federico Faggin and Stan Mazor.  The original plan was to use 12 custom chips for the device, but as the work progressed they decided that it would be so much more efficient if one of those chips could be programmable.  The final design used only four chips: the processor, a read only memory, a random access memory and an input/output chip.  As the work progressed Busicom ran into financial trouble so Intel agreed to absorb most of the development cost in exchange for the rights to the design.  Little did anyone realize how important this step was.  Busicom sold about 100,000 of the calculators and Intel decided to take the product to market.  It was announced on November 15^th, 1971 to little fanfare  Slowly the realization of the potential for a programmable chip dawned on the company even though the primary focus of Intel remained on the memory business.  Several generations followed, each one more powerful and larger than the last until the 8088 and 8086 arrived on the scene in 1978.  The 8088 was the processor selected by IBM for the IBM Personal Computer that was announced in August, 1981.  In less than 10 years an accident of opportunity was transformed into the beginning of a cultural and engineering revolution.  The IBM PC was so successful that by 1983 Intel decided to abandon the memory business that had become extremely competitive with low margins and focus all its energy on the microprocessor business.  Andy Grove, the then CEO, is credited with making this prophetic decision.  It propelled Intel into becoming the largest semiconductor manufacturer in the world, driven by an almost fanatical drive to build faster and faster and more powerful but upward compatible microprocessors.

The original Intel 4004 comprised 2,300 transistors as shown below.  Today’s products the Core 2 Duo has more 200,000 times the number of transistors.  Moore’s Law of doubling the number of transisters per chip every two years is still in place as Intel promises to ship chips with 4 processors on each one within the next few months.

Where else but in this great country could this have happened?