Using synthetic DNA for data storage implies two complex steps of digital data processing, namely Encoding and Decoding, which are very different from what we are used to in the conventional Flash environment. Because of the intrinsic statistical behavior of the DNA storage errors (i.e. insertions, deletions, and substitutions), a simulator is required for figuring out the impact of different Encoding/Decoding strategies and algorithms on the storage capabilities of DNA. In this presentation we will describe DNAssim, a full-system simulator for DNA storage which enables a complete design exploration of both Encoding and Decoding.