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Cognizant of financial troubles at Busicom, and sensing the market potential of the product, Intel made what was perhaps the most important decision in the history of the company: they returned their $60,000 design fee to Busicom and agreed to sell them the chip set at a lower cost in exchange for Busicom's surrendering of its exclusive rights. Now with its complete ownership, Intel announced the chipset to the world in November 1971 with an advertisement that touted "Announcing a new era of integrated electronics: A micro-programmable computer on a chip!" After a campaign to educate the engineering community about the MCS-4 chip family, it began to find a home in control applications that included traffic lights and taxi meters. While these initial usages were relatively unsophisticated, they represented a power and flexibility at a low cost and with a small footprint - a combination never before possible.
|a6=The key technical obstacle was adapting Intel's P-channel silicon-gate MOS process to accommodate 2300 transistors in a chip size that was economical and practical to manufacture in volume. As discussed with reference to Federico Faggin in the [[Media:Ref1-Electronics MOS-Story(29-Sept-1969).pdf|29 Sept 1969 issue of <i>Electronics</i>]], the new direction in MOS technology at that time was the development of a self-aligned gate MOS process (to reduce parasitic capacitances) combined with a lower power supply voltage (from -24 volts to -15 volts) by reducing the maximum threshold voltage from -9 volts to -3.5 volts. This was accomplished for the first time in 1968 by using polysilicon instead of aluminum in the gate electrode. The result was a technology that, for the same power dissipation, resulted in (1) a 5x speed improvement, (2) reduced leakage current (by more than 100 times), (3) higher circuit density (especially for random logic designs) using the buried contact, which allowed fabricating an insulated contact between junctions and polysilicon, thereby resulting in half the chip area for the same function, and (4) higher reliability by using phosphorus gettering to reduce metal impurities, which was not possible with an aluminum gate. This increase in speed and functionality within a single chip allowed the 4004 to be a single-chip CPU, with a resultant improved cost and greatly improved performance, as compared with a multi-chip implementation.<br>