Small enough to fit on an infants fingertip, the 15mm-squared intel 4004 ran at 108KHz (yes, we mean a tenth of a milligigahertz) and addressed only 640 bytes of memory when it debuted in 1971. Thirty years later, the level of integration of its 2,300 transistors falls far short of todays expectations: If a Pentium 4, with its 42 million transistors, were built to the same device density, it would have a die area of almost 270,000mm squared—or almost three square feet, rather larger than the 217mm squared that is still enough to make the Pentium 4 a giant among "micro" processors.
Newly arrived engineer Ted Hoff proposed the 4004 as a solution to Intels reluctance to develop 13 specialized chips to perform the functions of high-performance scientific calculators. Until then, Intel had produced only three types of device. After jointly developing the device with Japans Busicom, Intel bought back the rights for $60,000. Happy 30th birthday, microprocessor.