Ted Hoff’s General Purpose Microprocessor

“…even though science and technology are wonderful, what really gets them out there for people to use is to have businesses built around them. It takes savvy businessmen as well as savvy technologists to make that work.”

Tedd Hoff


Ted Hoff had access to then state-of-the-art vacuum tube circuits in high school. In 1954, he graduated and gained access to then-new transistors and magnetic core memory. Eventually, he earned a bachelor’s degree when came to Stanford, earning a Ph.D. in 1962.

During that time, he talked to Rex Rice, an on-campus recruiter for Fairchild Semiconductor. Particularly, the Traitorous Eight founded Fairchild and Doriot student Arthur Rock funded the business.

Hoff believed the new field of integrated circuits could work well for memory, replacing the clunky and relatively enormous core memory. Eventually, this led to a referral to Bob Noyce. He worked at Fairchild but was starting a new company, Intel. Evidently, Noyce intended Intel to focus on semiconductor memory and was searching for somebody with Hoff’s background.


In 1970, while waiting for the technology to mature, Intel decided to build one-off chips for the desktop calculator market. Eventually, Hoff was assigned to assist building a chip for Japanese company Busicom. At first, Japanese engineers were expected to do all the work with Hoff acting as a liaison and coordinator.

However, Hoff noticed the Japanese design was sub-optimal. There were about a dozen chips and the entire system appeared needlessly complex. Hoff raised his concerns to Noyce who encouraged him to make a “backup” design.

Hoff’s design incorporated random access memory and programmability. It was vastly simpler yet overall more powerful by being programmable rather than single-purpose. After a meeting, the customer adopted Hoff and Intel’s design.

Federico Faggin joined Intel and refined Hoff’s idea, optimizing the general-purpose chip to take advantage of Intel technology. By January 1971, the team had a fully functional microprocessor.

The Microprocessor is Born

Their original goal was an embedded system, not a PC chip. Embedded systems are specialty chips that people never see; they make other machines work. The final chip, renamed the Intel 4004, contained between 2,100 and 2,300 transistors, depending upon how one counted. In 1974, Intel’s 4004 was followed by the 8008 then the 8080. That chip became the foundation of the Altair, the first microcomputer. The Altair inspired a young Bill Gates and Co. to start a software company and a young Steve Jobs and Wozniak to form a computer company.

Electronic Desktop Calculator

Desktop calculators led the idea of computers small and cheap enough to sit on an individual’s desk. Eventually, they also became the impetus for the general-purpose microchip.


The first desktop electronic calculator is the ANITA Mark VII and ANITA Mark VIIII, both launched late 1961. The Bell Punch Co. of Britain designed the ANITA. Markedly, they used vacuum tubes and cold-cathode, and nixie tubes for the numerical display. Norbert (“Norman”) Kitz led the design and engineering work.

Eventually, the ANITA VII sold in continental Europe and the ANITA VIII in the UK and the rest of the world. However, soon after launch, Bell dropped the ANITA VII and consolidated the product line.

Cost was a major factor producing the ANITA. To make the calculator, Bell Punch needed to sell the product for about 1/100th the least expensive electronic computers of the day cost. Eventually, ANITA went on the market for £355 (about £7,800 in 2018, about $10,500 USD). In contrast, the least expensive general-purpose computers in 1961 cost about £50,000 (just over £1 million adjusted to 2018). The device weighed 34 pounds (15.5 kg).

Transistor-Based Calculators

Eventually, by 1964, competitors started to release calculators that used transistors rather than tubes. Sharp, Canon, Sony, Toshiba, Wang, and countless others released transistor-based calculators. However, these calculators were similarly priced to the ANITA, or even more expensive. Significantly, were significantly smaller and lighter due to the lack of tubes.

The Soviet Union literally weighed in with the T-64 built in Bulgaria. However, despite the use of semiconductors, the calculator weighed 8kg (17.6 lbs.) and is the first calculator to compute square roots.

Calculators continued to decrease in price, size, and increase in performance.

General-Purpose Microchip

Many calculator companies hired Intel, a young company, to produce custom chips for their calculators. Eventually,  in 1970, Intel engineer Ted Hoff instead created a general-purpose chip for Japanese company Busicom. Unlike other calculator chips, the Busicom chip was programmable to do multiple functions, not only those specific to one calculator. In 1971, Intel licensed the chip back and rebranded it the Intel 4004, Intel’s first general-purpose microprocessor.