Simplicity

2025-09-14

Sep 15, 2025

Simplicity is in the eyes of the beholder.

Is 72 of something simpler than 4,100 of some other thing?

Early 8-bit CPUs

The Motorola MC6800 (1974) had about 4,100 transistors, while the MOS Technology 6502 (1975) had about 3,510. Both were 8-bit microprocessors from the mid-1970s, with the 6502 being a cheaper alternative. Its simpler design and fewer transistors made it popular in home computers like the Apple II, Commodore 64, and Atari 2600.

The MC6800 had 72 opcodes with different addressing modes, giving 197 total variations. The 6502 had 56 opcodes with different addressing modes, giving 151 total variations. The MC6800 had a more comprehensive instruction set with more addressing modes and instructions, which contributed to its higher transistor count and complexity. The 6502’s simpler instruction set was part of its cost-reduction strategy.

Both processors used 8-bit opcodes, so they could theoretically support up to 256 different instructions, but neither used the full space. The 6502 had several undocumented opcodes that still performed operations due to its instruction decoder design.

Modern CPUs

Modern CPUs contain billions of transistors.

A single modern smartphone chip could theoretically contain 10-20 million complete MC6800 processors - each one capable of running the software that powered early personal computers, calculators, and arcade games.

Your smartphone could contain 15-25 million complete 6502 processors - enough computational power to run millions of Apple IIs simultaneously!

Paul’s Substack

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