Inventing The Microprocessor: The Intel 4004

We recently looked at the origins of the integrated circuit (IC) and the calculator, which was the IC’s first killer app, but a surprise twist is that the calculator played a big part in the invention of the next world-changing marvel, the microprocessor.

There is some dispute as to which company invented the microprocessor, and we’ll talk about that further down. But who invented the first commercially available microprocessor? That honor goes to Intel for the 4004.

Path To The 4004

Busicom calculator motherboard based on 4004 (center) and the calculator (right)
Busicom calculator motherboard based on 4004 (center) and the calculator (right)

We pick up the tale with Robert Noyce, who had co-invented the IC while at Fairchild Semiconductor. In July 1968 he left Fairchild to co-found Intel for the purpose of manufacturing semiconductor memory chips.

While Intel was still a new startup living off of their initial $3 million in financing, and before they had a semiconductor memory product, as many start-ups do to survive they took on custom work. In April 1969, Japanese company Busicom hired them to do LSI (Large-Scale Integration) work for a family of calculators.

Busicom’s design, consisting of twelve interlinked chips, was considered a complicated one. For example, it included shift-register memory, a serial type of memory which complicates the control logic. It also used Binary Coded Decimal (BCD) arithmetic. Marcian Edward Hoff Jr — known as “Ted”, head of the Intel’s Application Research Department, felt that the design was even more complicated than a general purpose computer like the PDP-8, which had a fairly simple architecture. He felt they may not be able to meet the cost targets and so Noyce gave Hoff the go-ahead to look for ways to simplify it.

Continue reading “Inventing The Microprocessor: The Intel 4004”

How The Integrated Circuit Came To Be

As the saying goes, hindsight is 20/20. It may surprise you that the microchip that we all know and love today was far from an obvious idea. Some of the paths that were being explored back then to cram more components into a smaller area seem odd now. But who hasn’t experienced hindsight of that sort, even on our own bench tops.

Let’s start the story of the microchip like any good engineering challenge should be started, by diving into the problem that existed at the time with the skyrocketing complexity of computing machines.

Continue reading “How The Integrated Circuit Came To Be”

The Silicon IC 50th Anniversary

Today marks the 50th anniversary of the first silicon integrated circuit patent. We should not have to explain how important the integrated circuit to this crowd, but it is the biggest thing in electronics since sliced bread.

[Robert Noyce] received the landmark patent on April 25th 1961, and went on to found a little known company you might of heard of (along with [Gordon Moore]), Intel Corporation. He was not the first to invent the IC, that privilege goes to [Jack Kilby] of Texas Instruments, though that design was using a germanium wafer. Silicon has many advantages over previous technology and has become the main technology of IC’s even 50 years later fueling the electronics, computer and mobile industries.

Check out the little article above, and also be sure to check out this video on IC construction we posted about a few months ago from the other company [Robert Noyce] help co-found, Fairchild Semiconductor.