A history of ARM, part 1: Building the first chip

The small UK company was famous for winning a contract with the British Broadcasting Corporation to produce a computer for a national television show. Sales of its BBC Micro were skyrocketing and on pace to exceed 1.2 million units.

But the world of personal computers was changing. The market for cheap 8-bit micros that parents would buy to help kids with their homework was becoming saturated. And new machines from across the pond, like the IBM PC and the upcoming Apple Macintosh, promised significantly more power and ease of use. Acorn needed a way to compete, but it didn’t have much money for research and development.

Sophie Wilson, one of the designers of the BBC Micro, had anticipated this problem. She had added a slot called the “Tube” that could connect to a more powerful central processing unit. A slotted CPU could take over the computer, leaving its original 6502 chip free for other tasks.

But what processor should she choose? Wilson and co-designer Steve Furber considered various 16-bit options, such as Intel’s 80286, National Semiconductor’s 32016, and Motorola’s 68000. But none were completely satisfactory.

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