[Thread] A look at the first ARM processor ARM1, which was built in 1985 and had 25K transistors, next to Apple's M1 chip, which has 8 cores and 16B transistors
Ken Shirriff's die-level comparison lands three days after Apple's M1 announcement and puts Apple's first Mac silicon in a 35-year arc: the ARM1's 25K transistors versus the M1's 16B on the same architecture lineage. The timing matters because the M1's debut was the payoff of a long-signaled move — Kuo had flagged an ARM-based Mac on an Apple-designed chip as far back as February 2020.
The comparison also frames what reviewers were measuring that week: AnandTech's fan-cooled M1 Mac mini deep dive found the chip besting Intel's parts and matching AMD's Zen 3, which is the performance claim the ARM1-to-M1 scale gap makes visually concrete.
First-order effects
Apple's M1 transition gets a public technical baseline: the Shirriff thread documents the ARM architecture's origin at 25K transistors in 1985, giving the 16B-transistor, 8-core M1 a traceable lineage rather than an overnight origin story.
Intel and AMD face a fresh framing problem — coverage of the M1 already benchmarks it against Intel's chips and AMD's Zen 3, and the ARM1 comparison reinforces that Apple is competing on the same ISA family that started as a low-power Acorn design.
Second-order effects
The M1's early performance validation, combined with Apple's vertical integration history from PowerPC through the A-series documented in Apple's CPU history thread, pressures other PC makers to take ARM seriously as a laptop silicon source rather than an mobile-only architecture.
ARM's PC credibility compounds: Mercury Research later measured ARM's PC chip share roughly quadrupling year over year once Apple's ARM-based M1 Macs entered the market, giving Qualcomm and other ARM licensees a market signal to build against.
Third-order effects
If ARM's PC share keeps climbing from its post-M1 trajectory, the x86 duopoly of Intel and AMD loses its default position in laptops, and chip sourcing decisions shift toward whoever controls integrated ARM SoC design — a structure Apple's PowerPC-to-M1 history suggests it has been building toward for decades.
The 25K-to-16B transistor arc illustrates why [[/concepts#power-as-a-computing-constraint|power became the binding constraint]] in modern chip design: the ARM lineage won in PCs not by raw scale alone but by an efficiency head start that x86 incumbents must now engineer against.
The trend: Apple's M1 marks ARM's move from embedded and mobile origins into the PC mainstream, eroding x86's default hold on laptop silicon.
Here are the two dies at the same scale. The M1 is over twice as large physically as the ARM1. It has 16 billion transistors vs 25,000 for the ARM1. If you built the ARM1 using the same technology, it would be a pixel-sized speck. https://twitter.com/...
The ARM1 had an 84-pin package, 30mm wide. The M1 package is smaller at ~21mm wide, and has DRAM modules on it. Compare the yellow ceramic disc decoupling capacitors on the ARM1 board with the tiny 0402 capacitors surrounding the M1 die. (Photo shows packages at same scale.) http…
The ARM1 processor ran at 6 megahertz, while the M1 runs at 3.2 gigahertz, over 500 times faster. While the ARM1 was a single processor, the M1 has 4 high-performance CPU cores, 4 efficiency CPU cores, a 16-core neural engine, and 8-core GPU.
The ARM processor started with the Acorn RISC Machine project in 1983. Apple got involved in the late 1980s, using the low-power ARM 610 processor in the ill-fated Newton handheld. In 1990, Acorn, Apple, and VLSI Technology formed Advanced RISC Machines, with Apple owning 43%.
To see the ARM1 in action with its 25,000 transistors blinking away, check out the simulator created by the Visual 6502 team: https://visual6502.org/...
Looking at the ARM1 die, you see functional blocks such as 100 bytes of registers and a basic 32-bit ALU. On the M1 die, similar-sized functional blocks are a 12-megabyte cache and a complete 64-bit CPU core. It shows what Moore's law has done over 35 years. https://twitter.com/.…
With Apple's recent announcement of the ARM-based M1 processor, I figured it would be interesting to compare it to the first ARM processor, created by Acorn Computers in 1985 for the BBC Micro computer. Designers were Sophie Wilson and Steve Furber.
It's absolutely nuts that Acorn's work on the BBC Micro and Archimedes would end up being the foundation of most Apple devices in the 2020s. https://twitter.com/...
I had an Archimedes back in the day. A3010. 2Mb RAM , a 1.6Mb floppy drive and no hard disk. Built in BBC Basic and bright green function keys. ARM250 processor OMG I loved that machine! https://twitter.com/...
A really superb thread on 35 years of processor development by @kenshirriff. I love this: “If you built the [1985] ARM1 using the same technology [as the 2020 M1] would be a pixel-sized speck.” https://twitter.com/...