The C64 was pretty much the same model for about a decade. The various iPhone models are probably too different to count in the same world-record category. The

The C64 was pretty much the same model for about a decade. The various iPhone models are probably too different to count in the same world-record category. The C64's lack of change is perhaps a reason why Commodore died. Jack was brilliant at squeezing hardware to get the max performance on a thin dime, but he didn't really give much thought to software compatibility, having a hardware-centric background. Thus, attempts to make a C64 follow-on that was compatible with the original C64 had too many problems. Without backward compatibility in a follow-on, it had no immediate advantage to existing competitors in the next performance bracket (generally, 16 bit). They considered entering the PC clone business, but it was already getting margin-thin and moving offshore at that point. They also considered a PC clone that was also C64 compatible, but couldn't make it viable. Bill Gates knew that software was where the lasting fortune was, not hardware.