History of the ARM chip
The ARM1 was designed in 1985 by engineers Sophie Wilson (formerly Roger Wilson) and Steve Furber of Acorn Computers.
The chip was originally named the Acorn RISC Machine and intended as a coprocessor for the BBC Micro home/educational computer to improve its performance.
Only a few hundred ARM1 processors were fabricated, so you might expect
ARM to be a forgotten microprocessor, a historical footnote of the 1980s.
However, the original ARM1 chip led to the amazingly successful ARM architecture with more than 50 billion ARM chips produced. What happened?
In the early 1980s, academic research suggested that instead of making processor instruction sets more complex, designers would get better performance from a processor that was simple but fast: the Reduced Instruction Set Computer or RISC.[6]
The Berkeley and Stanford research papers on RISC inspired the ARM designers to choose a RISC design. In addition, given the small size of the design team at Acorn, a simple RISC chip was a practical choice.[7]
The simplicity of a RISC design is clear when comparing the ARM1 and Intel’s 80386, which came out the same year:
the ARM1 had about 25,000 transistors versus 275,000 in the 386.[8]
The photos below show the two chips at the same scale; the ARM1 is 50mm2 compared to 104mm2 for the 386.
(Twenty years later, an ARM7TDMI core was 0.1mm2; magnified at the same scale it would be the size of this square
vividly illustrating Moore’s law.)
Die photos of the ARM1 processor and the Intel 386 processor to the same scale.
The ARM1 is much smaller and contained 25,000 transistors compared to 275,000 in the 386.
The 386 was higher density, with a 1.5 micron process compared to 3 micron for the ARM1.
ARM1 photo courtesy of Computer History Museum.
Intel A80386DX-20 by
Pdesousa359,
CC BY-SA 3.0.
The ARM1 is much smaller and contained 25,000 transistors compared to 275,000 in the 386.
The 386 was higher density, with a 1.5 micron process compared to 3 micron for the ARM1.
ARM1 photo courtesy of Computer History Museum.
Intel A80386DX-20 by
Pdesousa359,
CC BY-SA 3.0.
Because of the ARM1’s small transistor count, the chip used very little power: about 1/10 Watt, compared to nearly 2 Watts for the 386.
The combination of high performance and low power consumption made later versions of ARM chip very popular for embedded systems. Apple chose the ARM processor for its ill-fated Newton handheld system and
in 1990, Acorn Computers, Apple, and chip manufacturer VLSI Technology formed the company Advanced RISC Machines to continue ARM development.[9]
In the years since then, ARM has become the world’s most-used instruction set with more than 50 billion ARM processors manufactured. The majority of mobile devices use an ARM processor; for instance, the Apple A8 processor inside iPhone 6 uses the 64-bit ARMv8-A.
Despite its humble beginnings, the ARM1 made IEEE Spectrum’s list of 25 microchips that shook the world
and PC World’s 11 most influential microprocessors of all time.
