The Birth of Modern Microprocessors: Celebrating Intel 4004’s 50th Anniversary
Once upon a time, computers took up entire rooms. One technology that shook the world is Intel's 4004 microprocessor, which turned 50 this month. How did it help pave the way for smaller modern technology?
Birthed from a 1969 partnership with the Nippon Calculating Machine Corp., Intel unveiled a condensed set (the MCS-4) of four core computing chips. The standout from the lot, the Intel 4004 central processing unit (CPU), helped usher in the modern electronics era.
The brainchild of Federico Faggin, Stan Mazor, Marcian Hoff, and others was indeed revolutionary.
The first iteration of the Intel 4004 chip. Image used courtesy of Intel
Occupying merely a fingernail's area, Intel's diminutive CPU matched the processing power of the famed ENIAC computer—which conversely occupied an entire room.
In this article, let's dive into what else made the 4004 special and how it was foundational for today's microprocessors.
Introducing the Intel 4004
Before digging into specifications, it's important to remember that Intel's CPU offering actually wasn't the first microprocessor in use.
American Microsystems manufactured the MP944 in 1970 as part of the F-14 Tomcat's Central Air Data Computer. This chip helped enable real-time flight calculations for the U.S. Navy's leading fighter platform—one year before the 4004's launch.
The F-14 “Tomcat” microprocessor. Image used courtesy of First Microprocessor
Additionally, Texas Instruments finalized the design of its TMS1000 microprocessor before Intel's design hit the market.
However, Intel's early commercialization of the 4004 CPU helped quickly elevate it to ubiquity.
The preceding chips from American Microsystems and Texas Instruments held a special role militarily or were introduced to consumers much later. The TMS1000, for example, wasn't widely available until 1974.
This market advantage meant eventually led many manufacturers to base their designs on the 4004. Chipmakers would similarly use it as a blueprint for competing designs in the coming year.
A colorized schematic view of the 4004 CPU. Image used courtesy of Intel
That said, what did the Intel 4004 bring to the table?
- A compact design ideal for portable and stationary electronics alike
- A new random-logic design philosophy
- A new standard for system packaging and internal consolidation
- A smaller process standard for silicon gates
In terms of specs—while underpowered by modern standards—the 4004 was revolutionary for its time.
It clocked in at 740 kHz and was made on a tiny, 10-micrometer process. It could access 4 KB of program memory and 640 bytes of RAM.
These factors helped enable the Intel 4004 to process over 92,000 instructions per second, which was an incredible level of capability for the early 70s.
The first iteration of the CPU was 4-bit, featured 2,250 transistors, and was based on PMOS technology. This type of MOSFET was relatively cheap to produce at scale. It was also resistant to interference.
The final design, which lasted until 1982, retained the 4004's 16-pin configuration.
However, it's notable that the 4004's weaknesses—namely a limited stack depth, memory access complexity, and lack of interrupt support—helped spur development.
Intel also brought multiple refinements into being, starting with the packaging material. While the Intel C4004 kicked things off with a white ceramic package, the later P4004 boasted plastic packaging.
Intel's 4004 chip in plastic packaging. Image used courtesy of Intel
This packaging change suggests that the thermal performance of the CPU improved throughout its development lifecycle. Accordingly, plastics have become more economical and easier to work with industrially.
The 4004 Unlocked the Future of Microprocessors
Aside from being a commercial juggernaut, Intel's 4004 series was a runaway success as a technological proof of concept. Room-sized computers became nearly obsolete in one fell swoop.
The CPU and its successors like the 4040, 8008, and 8080 continued to prove our readiness for compact electronics. The game had fundamentally changed. Manufacturers and designers were now asking, "How much power can we pack into as little space as possible?" Additionally, the randomized logic behind the 4004 was eventually adapted by the many chipsets that followed.
Though it certainly didn't happen overnight, Intel excelled at achieving both developer and engineer buy-in around its chipset designs, which helped influence several new innovations.
The 4004 helped electrical engineers associate electronics with microprocessors, and these chips have become indispensable in the 50 years since. In 2020, the global market valuation for microprocessors reached $83.9 billion—a testament to their widespread use.
From 1971 to Now
Electronic devices are shrinking, transistor density is growing, and smaller internal layouts require minuscule microprocessors. This trend and the desire to outpace Moore's Law has driven chipset research forward by leaps and bounds.
The history of microprocessors is both rich and complex. However, we've seen some key trends emerge over the past decades.
Processor computing architectures have evolved from the 4004's 4-bit system to 8-bit, 16-bit, 32-bit, and now 64-bit. Other variations have also popped up through the years, as needed, to address computing limitations.
For example, the Panafacom group introduced the world's first 16-bit microprocessor commercially. Today's x86 processor family descends directly from Intel's 8086 CPU.
Memory access limitations mean that we'll someday have to make the jump to 128-bit—a futuristic CPU with roots traceable to Intel's maiden processor.
Intel's early work has enabled today's processing arms race, in which transistor counts and process-node shrinkage dominate. Fabricators can now pack innumerable times more transistors into tiny SoCs than they ever could previously.
As the programs run become more complex—and as AI algorithms become critical for many workloads—the microprocessor's relationship with software programming has become inseparable.
The 4004 CPU paved the way for smarter computing. Engineers are running with the technology they have. At the same time, companies pour billions into manufacturing and R&D.
Furthermore, quantum computing is on the horizon, and upcoming processors have quite a job ahead of them.
Neuromorphic computing is also gaining steam. Intel Horse Ridge II and Loihi 2 will be instrumental in this shift, though competitors will be keen to nip at their heels.
While Intel's 4004 supported a simple calculator, next-generation chips will function logically like the human brain, inconceivable in 1971.
All in all, there's plenty of buzz in the computing realm, and microprocessor development isn't slowing anytime soon. Oh, how far we've come, and yet so far to go.
The F-14 mentioned in the sixth paragraph was a Navy plane, not Air Force.