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A $25 chip made Apple possible
The first microprocessor
Intel's engineers built the first microprocessor in 1971 for a plain reason: they wanted to stop designing desktop calculator chipsets from scratch every time. Outsiders realized they could build their own personal computers around it, and thousands of tinkerers found configurations and uses Intel never dreamed of. There was no real demand yet. Early personal computers were expensive toys, and the experimenters laid the technical groundwork and built a community.
The price drop
Around 1975, a step change in the cost of microprocessors made the personal computer market viable. The Intel 8080 had an initial list price of $360, about $2,300 today. MITS could barely turn a profit on its Altair with chips at a bulk price of $75 each, about $490 today. Then MOS Technologies started selling its 6502 for $25, about $150 today, and Wozniak could afford to build a prototype Apple.
The 6502 and the similarly priced Zilog Z80 forced Intel's prices down. The budding PC community began spawning entrepreneurs, and a score of companies appeared, each with a slightly different product.
Why did the 6502 cost so much less?
The 6502 was designed by a team led by Chuck Peddle, several of whom had left Motorola, with the goal of making a processor cheap to manufacture. A smaller design meant more chips fit on each silicon wafer, and a single defect ruined fewer of them. At a 1975 trade show it sold for $25, while Motorola's rival 6800 sold for $175.
How did the 6502 end up in so many machines?
Wozniak built the Apple I around the 6502 in 1976, and the Apple II that followed in 1977 used it too. The same chip, or close variants, went into the Commodore PET and the Atari 8-bit computers. A modified 6502 core also ran the Nintendo Entertainment System.
Why did hobbyists build computers themselves?
In January 1975, Popular Electronics put the Altair 8800 on its cover as a kit that readers could assemble at home. The Homebrew Computer Club began meeting in Menlo Park, California, in March 1975, and members traded schematics and programs freely. Wozniak was a regular there, and the Apple I came out of that community.
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