Hardware Secret posted a series of quick reference tables containing the main specs of all Sempron processors released to date.
Here is a snippet:
"Sempron is an AMD CPU targeted to the entry-level market, i.e. to users that don't need a high processing power and are more worried with price than performance. Sempron main competitor is Celeron D from Intel and you can read our tutorial Sempron vs. Celeron D for a technical comparison between these two CPUs."