Advent of Computing Episode 71 - 6502, The Mini-Microprocessor
Dec 13, 2021
A lively walk through how a tiny, low-cost CPU reshaped home computing. Stories of corporate clashes, talent migration, and recession-driven opportunity. Design tradeoffs that trimmed instructions, registers, and silicon to boost yields. Early sales hustle, legal battles, and the KIM-1’s role in getting developers hooked.
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Motorola Built A Chip Family To Sell Systems
- Motorola's 6800 was conceived as a family of chips to sell complete systems to clients with varied I/O needs.
- Engineers surveyed customers and designed about 15 building-block chips so firms could assemble customized systems with standard parts.
How A Recession Fueled The 6502 Team Exodus
- Chuck Peddle left Motorola with seven co-workers during a 1974 recession and joined MOS Technologies to build the smaller processor.
- Economic layoffs and Motorola's Austin relocation motivated the team defections that made the 6502 possible.
Instruction Cuts Lowered Chip Complexity
- Peddle cut rarely used instructions to simplify the 6502's ISA and reduce silicon needs.
- The 6502 shipped with 56 instructions versus the 6800's 72, removing features like NEG to shrink circuitry.