It’s a rare advertisement that delivers exactly what it promises, but that was the case for Intel when it took out a half-page spot 43 years ago to tout its 4004 4-bit CPU in the November 15, 1971 issue of Electronic News promising “a new era of integrated electronics.” If anything, the ad undersold the product. The 4004 was the world’s first commercially available single chip microprocessor, and it would change computing forever.

You probably have at least a general idea that the central processing unit (or CPU) is the “brains” of your computer. It carries out the commands your various programs feed into it, allowing you to calculate tips, listen to music, or share pictures of your cat (or your lunch. Or your cat’s lunch…) with the push of a few buttons. The history of computing can largely be boiled down to the evolution of the CPU. The earliest computers didn’t have central command units that could carry out multiple commands, and had to be physically rewired to perform a new task. Central processing units came along to allow more versatility in what a computer would do, but they were bulky and slow, initially made up of vacuum tubes before advancing into transistor-based design.

The idea of containing a computer’s CPU on a single microchip was revolutionary. It allowed computers to become faster, smaller, and able to carry out more functions. The Intel 4004 was initially placed in a calculator released by Japanese manufacturer Busicom, beginning the era of microprocessor-powered consumer electronics.

Today microchips can contain multiple CPUs (or cores). A 4-bit CPU like the 4004 would be painfully slow and useless to a modern user, but the basic design of CPU’s hasn’t changed much from the 1950s. A common comparison is to say that today’s cellphones have more computing power than the earliest space shuttles. For what it’s worth, the crew designing the Pioneer 10 space probe, which launched from Cape Canaveral in 1972 and became the first spacecraft to escape our solar system, considered including the 4004 among its components. They decided against it on the basis that it was too new.

http://upload.wikimedia.org/wikipedia/commons/thumb/a/a7/KL_National_INS4004.jpg/727px-KL_National_INS4004.jpg