Nios II ModelSim simulation files

Hello there,

I have a question regarding on-chip memory init files, generated by SOPC Builder.

When I generate my Nios II system w/ SOPC Builder (ticking the "Simulation.Create project simulator files" box), several memory init files are created :

-/<sopc builder system name>_sim/<memory component name>.dat

-<memory component name>.hex

My question is : what's the difference between these .hex and .dat files?

Thanks all!