Inventor Ted Hoff's Keynote @ World IP Day- April 26, 2013 in San Jose, CA

Early Inventions and a Surprise Phone Call

At age 12, Ted Hoff became interested in electronics. He started reading electronic design magazines, built a short wave radio from a kit, and then built an oscilloscope and repaired TVs. After graduating from high school in 1954, Ted got a summer job doing electronic assembly work at General Railway Signal Company in Rochester, NY. This work involved using transistors, which were very new at the time.

During the following summers away from college he continued to work for General Railway Signal Company. That work led to two patents, one covering a circuit which detected trains using audio frequencies transmitted along the railway track and the second covering lightning protection for that circuit. The filing date for the first patent was in 1955 when he was only 17 years old!

After completing his university education (BEE 1958 from RPI, MS 1959 & PhD EE 1962 from Stanford), Dr. Hoff worked for Stanford Professor Bernard Widrow- PhD, as a Research Associate until he got a surprise phone call from Bob Noyce in 1968. Noyce had just left Fairchild Semiconductor and asked Ted to join a new semiconductor memory start-up company named Intel. Ted jumped at that offer and became employee #12 at Intel where he worked till 1983.

Semiconductor Memory Challenges & Opportunity

In his early years at Intel, Ted designed and developed semiconductor memories and generated application information for them. Intel's goal (which few at the time believed was realizable) was to replace magnetic core memory in computers. In 1970, Intel predicted the IC memory price would drop to 1 cent per bit by 1972 and that would be the crossover point. In contrast, today you can get over 100M bits of memory for 1 cent!

But cost was not the only issue. The most dense semiconductor memories at that time were DRAMs (dynamic random access memory), which were characterized by the structural simplicity of its storage cell: three transistors per bit compared to six used in static RAMs (SRAMs). Later DRAMs would be made with only one transistor and a capacitor to store each bit. Both static RAMs and DRAMs lose data if power is removed, while core memories do not.

In addition, DRAMs are volatile, e.g. storage is lost if the data are not accessed frequently. To ensure data retention, refresh circuitry was added to refresh each row of memory cells every few milliseconds. This made the DRAM controller's logic circuit more complicated than SRAM, but that was outweighed by the fact that DRAM is much cheaper per storage cell and because each storage cell is very simple thus providing higher densities.

Ted wrote a mini-textbook and Semiconductor Memories (he calls it a pamphlet) that this author used in a SCU Graduate EE course on that subject in Fall of 1971!

Custom Chips and the Invention of the 4004 Microprocessor

As the time to design, package, test and sell semiconductor memories was quite a long process, Intel decided to develop custom circuits for various customers in order to generate revenue. One of those was a Japanese company named Busicom who (in April of 1969) asked Intel to design MOS LSIs for a family of calculators. Hoff was assigned the duty of helping Busicom engineers transfer their chip specifications to appropriate engineering teams within Intel.

Many complex chips were involved in that initial design effort, e.g. BCD arithmetic, shift register control, keyboard scanner (and de-bouncer), printer control, display control, etc. As he learned more about the Busicom design, he became concerned that it might be a problem for Intel and with Bob Noyce's encouragement, Ted proposed to greatly simplify the chip set design by eliminating many chips in the family. The simplification was accomplished by implementing the functions as stored programs running on a very simple general purpose central processor. He was later joined by co-designers Stan Mazor and Fredrico Faggin. The architecture he had defined was sufficiently simple that it allowed the central processor to be implemented as a single chip which was released as the Intel 4004 (U.S. Patent #3,821,715). The 4004, a 4-bit microprocessor, was announced in November 1971. In subsequent years, Intel introduced the 8008 and the very popular 8080 microprocessor.

By 1975 the microprocessor was established as a replacement for many MSI random logic designs and as an embedded controller for many different types of devices and equipment.

Monolithic CODEC for Digital Telephony

In 1975, Bob Noyce asked Hoff to study the telephone industry to see if there might be a role for Intel to play. Hoff put together a team that developed a single chip CODEC (COder-DECoder), which converted between the analog signals associated with a conventional telephone call (POTS) and a standard digital telephony format known as Pulse Code Modulation (PCM).

At the time, the principal use of CODECs was for T1 carrier digital transmission between telephone company (telco) central offices. However, the Intel CODEC allowed extending the use of that PCM digital format into new application areas, such as private branch exchanges (PBXs).

The CODEC does conversions in both directions between analog and digital representations. Analog signals are converted to a 64 kilobit-per-second PCM digital signal and vice versa. Voice coding and signaling are included.

With the signals in digital format, Hoff recognized that some functions usually performed by analog circuits, such as touch tone processing, would need to be handled digitally. His group developed an early Digital Signal Processor (DSP) to provide such functionality. When a CODEC is used, some filtering of the analog signals is needed, and Ted was fortunate to have consulting assistance from Professor Paul Gray of UC Berkeley. The result was that Intel could offer its CODEC with a switched-capacitor filter. The project succeeded and by 1980 Intel was offering CODECs, switched-capacitor filters and a DSP chip. These telephony LSIs appear to have been the first commercially available.

Career after Intel

In early 1983, Ted joined Atari which had extensive R&D programs underway for PC applications and video games. Unfortunately, Atari didn’t have good financial controls nor good visibility into its market. While initially very profitable, the video game market really started to saturate. Without market visibility, Atari overinvested. They went from annual revenue of well over $2 billion down to below $1 billion in the space of a year. The unanticipated market changes and bad financial controls led Warner Communications to sell the company in mid 1984.

In 1986, a former close co-worker of this author (Gary Summers at Signetics from 1976-79) started a company called Teklicon to do consulting to attorneys who were looking for either testimonial experts or advice about where to find particular art (i.e. intellectual property or patents). Ted worked with Teklicon from 1986 doing IP research and expert witness work till his retirement in 2007.

In this, his second career, Ted learned that patents were critically important to the semiconductor and high tech industries. He thinks that IP awareness should be part of every engineer's college education.

Awards

Ted received the National Medal of Technology and Innovation from President Obama in November of 2010. He was awarded the Stuart Ballantine Medal in 1979 and The Franklin Institute’s Certificate of Merit in 1996. Hoff was inducted into the Inventors Hall of Fame in 1996 and goes there each year for a reunion with fellow inventors. He was a recipient of the Kyoto Prize in 1997, and the James Clerk Maxwell Award of the IEEE in 2011. He was made an Eminent Member of the IEEEs Eta Kappa Nu in 2013. He is a Life Fellow member of the IEEE.