The MOS 6502 was created as a cheap alternative to the Motorolla 6800, and powered a lot of the consumer electronics in the 1980’s. Its layout was created by one man in one iteration with no errors.
These days, you can’t design and lay out a computer chip without a computer. An Intel Core 2 chip has hundreds of millions of transistors. The 6502 had 3,510, and an engineerâ€”a person, not a computerâ€”had to draw each one by hand to lay out the chip. Mainly it was a single engineer, Bill Mensch.
The original paper plans are long gone, but a team managed to a create a visual simulation of the 6502 at transistor level.