How it is work? With the normal SAVE command make a Spectrum tape sound.
There're some rules about native ZX Spectrum cassetes and how to deal with snapshots, which I forgot to tell:
1. Before any native ZX cassete operations (load or save) it is nessessary to press F1 in order to increase the memory access timeout, so that the system gets approximately the same with the ZX Spectrum performance
2. After the native ZX cassete operations press F2 to resume the normal memory access timeout
5. After loading Spectrum program and completing any operations you want to be stored in snapshot, press F5. You will return to the Enterprise enviroment... By the way, typing ":sp" will return you to the same situation in the Spectrum machine, which was held in the moment you've pressed F5
6. To save a snapshot type ":sp $....."
7. To load a snapshot type ":sp #....."