Swan is ZX Spectrum 48 emulator.
Only Spectrum 48k is emulated. During developing, the focus has been on achieving accurate emulation of the most popular model. Later models might be emulated in future, but it is not a priority.
Note: to have sound in Swan, you need portaudio library (http://www.portaudio.com/). Without portaudio Swan will work, but will not produce any sound.