Designed as a followup to the millions-selling C64, the C128 was a different beast altogether - a dual personality machine. Not only did it contain a 6509 CPU for it's built-in C64 mode but it also contained a Z80 CPU for CP/M compatability, hence the CP/M disk in the box. It could display either 40 or 80 columns on the supported RGBI or Composite video monitor, and 40 columns only on a domestic TV. While there were many applications written for the CP/M side of things not much appeared for the 128 mode; most people used the built-in C64 mode.