In the early 1970s it became clear that integrated circuits were going to be
a big deal. New electronics systems had the potential to remake modern society.
But as chips swelled to tens of thousands of transistors, designers began struggling
with their increasing complexity. It threatened the advancement of the industry.
Then in 1980, two computer scientists, Carver Mead and Lynn Conway, released a textbook
that sparked a semiconductor design paradigm shift.
In this video, we look at how VLSI systems design revolutionized the industry.
In 1971, Intel released the market's first commercial microprocessor:
the Intel 4004. Manufactured on 2-inch wafers using 10 micron lithography technology,
the 4004 had 2,300 transistors. It was a technical breakthrough.
Intel originally intended to exclusively sell the 4004 to a Japanese company called Busicom.
Busicom had wanted a set of integrated circuits for their line of electronic calculators.
However, Intel eventually decided to introduce the microprocessor to the open market.
They advertised it as a "new era in integrated electronics".
And for once, the marketing was right on the dot. Integrated circuits were the future.
However, there was a big problem that many companies and manufacturers faced
when making sophisticated integrated circuits: You only needed a genius.
The 4004's designer - Federico Faggin - had been a unicorn. He understood computers,
designed both logic and circuits, and was experienced in developing both process and
product. He used his intimate knowledge of silicon gate technology to develop a literal piece of art.
Federico and lead Busicom engineer Masatoshi Shima literally cut out strips of rubylith themselves
so that the lithography machine can transfer this beautiful chip design from paper to wafer.
Throughout the 1970s, the only people capable of designing chips were like Faggin.
People who knew everything about semiconductors from the gates to the fabrication process.
And early on this worked - barely.
By the end of the decade however, it became clear that this cannot continue.
Development was advancing forward at a rapid pace. New roles and specializations were being created,
and even the geniuses were having trouble keeping up.
By now it was becoming clear that within 10-20 years, commercially sold chips were
capable of having millions of transistors on them. If the designers could keep up.
Thus in 1976, Caltech and Xerox PARC - the famous research lab in Palo Alto - embarked
on a joint research project to easily create silicon systems for personal computers.
Two of the people named to the project were a Caltech professor named Carver Mead
and LSI Systems Group leader Lynn Conway.
Mead served as a high-level consultant to Intel and had
popularized the "Moore's Law" term after Gordon Moore's 1965 article.
Conway had been an expert in computer architecture with experience at IBM.
Together, the two created a standardized system design methodology. Tied together
with a set of simple design rules. VLSI, which stands for Very Large Scale Integrated Circuits.
For inspiration, Conway harkened back to the days of DC and AC. At the turn of the century,
DC technology was dominant but had started to show its age.
On the other hand, AC was emerging and showed a lot of potential,
but few people knew how to use it. Calculating the voltages across AC networks at the time
required calculus, a lot of time and much difficulty.
Then in 1893, an American immigrant from Germany named Charles Steinmetz broke the logjam by
crafting a series of design rules that simplified the math and produced predictable results.
Conway envisioned her VLSI principles doing the same:
Taking all the accumulated, extremely complex knowledge on logic design,
circuit design, and circuit layout and turning it into an elegant set of simple rules.
These rules can be used to design entire, whole systems not just circuits.
Stay within the design rules and everything will work the way it is supposed to.
The most important task in VLSI design is to harness and manage complexity.
To do this, VLSI looked to concepts of software programming
to bring structure to designing tens of thousands of transistors:
Abstraction, hierarchies of systems and sub-systems, and the use/reuse of common "blocks".
It introduced the design process flow that I talked about in my previous video.
You design the chip from the top-down. Start with the overarching structure,
define the circuits, and then finally connect those circuits together.
Critically, Conway came up with the idea of defining all the design rules using length ratios
rather than length dimensions. The basic length unit would be a unit Conway called "lambda".
Lambda-based design allowed semiconductor designers to smoothly transition from one
node process to another as those processes shrank. Now each circuit "block" could be
shared and reused without concern about the node they were originally designed for.
With VLSI, you can create a specific product
using generic components pulled out of a standard cell library. In this way,
it made hardware much like the software it ran on - a particularly unique feature with silicon.
But how to popularize the idea? In June 1977 during an evening team brainstorm session,
Conway hit upon the idea of turning their new design system into a textbook. Self-published
using PARC's computers, the book might help disseminate their ideas. Spoiler alert, it did.
Over the next few months, a variety of authors including Mead and Conway,
the principal author, worked on the book - titled "Introduction to VLSI Systems".
They added practical examples to help illustrate the principles.
And they worked with and received feedback from university professors around the country
using a new-fangled thing called the ARPAnet.
Then Conway was invited to go to MIT in 1978 and teach a VLSI course to some senior and
masters-level students. She designed the course to get students designing as soon as possible:
Rules and concepts in the first half, projects in the second half.
Despite only having primitive EDA tools and at certain points were checking their work by hand,
the students produced correct, working designs.
One student, Guy Steele Jr, designed a complete LISP microprocessor.
He would later design the original command set for Emacs.
Hewlett-Packard used a 6-micron silicon gate process to produce those designs
and shipped the final chips back to MIT in January 1979.
Conway's 1978 MIT course spawned many others around the country. 120 universities
were offering VLSI courses by 1983 and they were a revelation for young chip designers.
The textbook would be translated into various languages, including Russian - illegally.
A guy at Stanford, Jim Clark, learned VLSI from Lynn Conway in one summer at Xerox PARC.
He went on to design the "Geometry Engine" chip,
a revolutionary graphics processor. Later on, he would found Silicon Graphics.
VLSI reimagined chip design as something modular,
allowing for the separation of semiconductor design and its manufacture. Specialists can
now focus on optimizing one part of the process without also needing to become experts in another.
In 1978, DARPA identified VLSI technology as a space of interest and began funding additional
research at universities like Berkeley, MIT, Carnegie Mellon, Caltech, and more. The program
was very open. Researchers can share whatever they found, and very little was classified.
By 1982, DARPA was spending nearly $100 million a year on its VLSI program.
The program eventually spun off into multiple initiatives surrounding computer-aided design,
workstations, and RISC architectures. Many of these innovations are still used to this day.
There remained one thing missing. Mead and Conway envisioned a semiconductor industry
exploding with small chip companies doing all sorts of niche things.
Sort of like a Cambrian Explosion of weird and fun semiconductor startups.
However, that did not happen right off the bat and the reason was money.
The immense capital expenditures associated with cutting edge semiconductor manufacturing
kept companies out of the industry.
At the end of that first 1978 MIT course, students got to actually use
the chips they designed. This particular effort would eventually lead to the Multi Project Chip,
where multiple designs can be fabbed on a single wafer, saving on cost.
This technology was transferred to USC, which in 1981 launched MOSIS,
an e-commerce service provider for US universities. Students submitted
their designs to MOSIS over the internet. MOSIS batched them together and quickly fabbed them.
MOSIS was the first "independent foundry". But it restricted itself to American academia. Various
other countries launched their own versions. For instance, France's Circuits Multi-Projets or CMP.
Over in Taiwan, Morris Chang accepted an offer to found and lead a new semiconductor company.
Reflecting upon his industry experience, he decided this
company would service small semiconductor design teams without a fab of their own.
Taiwan Semiconductor Manufacturing Company or TSMC turned the MOSIS service into a commercial
enterprise. And this simple idea would in turn make TSMC into a $600 billion giant.
The golden age of VLSI ended in the 1990s as processors advanced to the point where using
and reusing standardized IP blocks started to interfere with chip size and performance.
Standard cell blocks wasted space, and that could no longer happen.
That being said, the VLSI paradigm helped push the industry for over a decade.
Helping to fuel the hundred billion dollar electronics boom of the 1980s.
Reflecting on it, VLSI was as much a philosophical breakthrough as it was a technological one.
The way it aligned and organized the thoughts of a generation of students,
is worth learning as today's semiconductors reach new unprecedented sizes and complexities.
Alright that's it for tonight. Thanks for watching. If you enjoyed the video,
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