Snapshot file formats
BASin can open and save .sna and .z80 files. These are the most popular snapshot file formats used by Spectrum emulators.
If you don't need to load your programs into other emulators, you should use the .bas file format instead.
A snapshot describes the complete state of the emulated Spectrum at the time it was saved, including the memory contents, port states, and register contents. When you open a snapshot in BASin, the BASIC program, variables, and user-defined graphics are extracted from it and converted into a tape block which the ROM loader understands.
Note: BASin saves 128k snapshots in a different manner to 48k.
When saving a snapshot, BASin checks to see which hardware it is compatible with - by testing for 128k specific commands, and also for the use of the UDGs "T" and "U" - which would denote a 48k snapshot for the majority of cases. If there is a clear case for one or either of the two hardware models, BASin will choose that format for saving. If there could reasonably be a choice, then BASin will ask you (assuming you have the relevant options set) which you want to use.
48k Snapshots work as expected - they are a dump of the memory and the state of the emulation as it was when the snapshot was saved. However, due to the fact that BASin is primarily a 48k emulation, 128k snapshots are created by inserting your program and silicon disc contents into a 128k snapshot. This means that when you load the snapshot, you will find yourself at the main 128k menu. To examine your program or run it, you must choose "128 BASIC" from this menu.
Note: The .z80 file format, developed by Gerton Lunter for his Z80 Spectrum emulator, has gone through a series of changes, making newer files incompatible with older versions of the emulator. You can choose your preferred version on BASin's Files tab.