[Taniwha]

he sort of misses that the 8080 and 6800 were in the market before the 6502 - it was a latecomer.

The big architectural advance was two index registers, otherwise it was really sort of a 6800 (from a programmer at the times point of view)

As mentioned above having a clock that could be created by meere mortals was a big advance (previoud chips required you to be able to drive what must have been a complete unbuffered clock tree - rail to rail voltages and high peak current.

The thing he misses about yield is that for a fixed per wafer defect rate there's a point where reducing die size to 1/4 reduces the yield fallout by almost that much

[vidarh]

It was explicitly a "sort of 6800". Chuck Peddle was on the 6800 design team, and so was his co-designer for the 6502 - Bill Mensch - and Rod Ogill that did the 6501.

Peddle tried to sell Motorola on making a cost reduced version. When Motorola refused to let him work on a cheap version, he left to do the 65xx.

Their first model - the 6501 - was designed to be pin compatible with the 6800, and resulted in a lawsuit from Motorola that almost bankrupted MOS.