From Turing to LLMs and Beyond

Hardware Evolution: Room to Pocket

From 17,468 vacuum tubes to 28 billion transistors — on your fingernail
Illustration companion to Issue 2: Building the First Brains

Section 1: The Shrinking Machine

Five eras of computing hardware, drawn to the same relative scale. The human is 170 cm tall.

ENIAC (1945) person 170 cm ~30 meters long 17,468 vacuum tubes | 30 tons | 150 kilowatts
Vacuum Tube Close-Up Actual size: ~10 cm tall. The size of your thumb. Cathode Glass Envelope Sealed vacuum inside Plate (Anode) Collects electrons Control Grid Controls electron flow This is the "switch" Filament Heats cathode to emit electrons Base Pins Connect to the circuit One switch. Size of your thumb. Runs HOT.
The First Transistor (1947) Bell Labs, New Jersey. Bardeen, Brattain, and Shockley. germanium emitter collector base U.S. dime 18mm ~1 cm Same job. 1/100th the size. Cool. Reliable.
The Integrated Circuit (1958) Jack Kilby at Texas Instruments. All components on one chip. ~5mm Half the 1cm transistor magnified 50x Thousands of transistors on a single chip.
Modern Processor (2024) Apple M4 / AMD Ryzen class. 3nm process technology. CPU GPU NPU MEM ~2 cm 2x the first transistor magnified 10,000,000x silicon substrate gate 3nm FinFET Transistors ~30 nm How small is 3nm? DNA strand: 2.5 nm wide Transistor gate: 3 nm ≈ 28 billion transistors. Each one 15 atoms wide.

Section 2: By the Numbers

Three machines, eight decades apart. Every metric tells the same story: more for less.

ENIAC (1945) IBM PC (1981) iPhone 15 (2023)
Size
Room (167 m²)
Desktop
Pocket
Weight 27,000 kg
11 kg
0.17 kg
Transistors 17,468 tubes
29,000
19 billion
Speed 5,000 ops/s
500K ops/s
2 trillion ops/s
Power 150,000 watts
150 watts
5 watts
Cost $7,000,000
(today's dollars)
 $4,500 $999
The pattern: Every 18-24 months, transistor density doubles and cost halves. Gordon Moore observed this in 1965. We call it Moore's Law -- and it held for over 50 years. The iPhone in your pocket has roughly a million times the computing power of ENIAC, uses 30,000 times less energy, and costs 7,000 times less.

Section 3: The Switch That Changed Everything

Three technologies, one job: let current flow, or stop it. ON or OFF. 1 or 0.

Vacuum Tube ~10 cm cathode grid plate e- flow Heated cathode boils off electrons. Grid voltage controls whether they reach the plate. ON: Electrons flow. OFF: Grid blocks them. Hot, fragile, power-hungry. Burns out like a light bulb. Transistor (MOSFET) ~1 mm to ~1 µm silicon source drain gate current flow Voltage at the gate creates a channel in the silicon. Current flows from source to drain through the channel. ON: Voltage at gate lets current flow. OFF: No voltage, no flow. Cool, solid-state, no moving parts. Lasts decades. Modern FinFET 3 nm gate wraps 3 sides source drain silicon "fins" The channel is now a 3D "fin" rising from the silicon. The gate wraps around 3 sides for better control. Same principle. A billion times smaller. 3nm gate length. 15 silicon atoms across. Switches on and off 3 billion times per second.

Section 4: If Transistors Were People...

Putting billions into perspective with familiar numbers.

1945
ENIAC
17,468 vacuum tubes
= a small town
1971
Intel 4004
2,300 transistors
= a village
1993
Intel Pentium
3.1 million transistors
= the population of Chicago
2024
Apple M4
28 billion transistors
= 3.5x the entire world population
Crammed onto a chip smaller than your thumbnail.
Transistor Count Over Time (logarithmic scale) 17K 1945 2.3K 1971 3.1M 1993 291M 2006 15B 2021 28B 2024
The punchline: The device you are reading this on contains more transistors than there are grains of sand on a typical beach. Every single one of them does the same job as a hot, fragile vacuum tube from 1945 -- it switches on, or it switches off. The entire digital world is built from that one trick, repeated billions of times a second.
← Back to Issue 2: Building the First Brains
From Turing to LLMs and Beyond — A 10-issue educational comic series about the history of computing