An emulator is a program that allows one system (eg. Windows) to run programs built for another system (eg. ZX Spectrum). It is mainly used to play old 8-bit games on today’s PCs. In other words, a complete waste of time.
What we will do is emulate Windows on a Linux system. Then we will run a DOS emulator under Windows. Then we will run a Commodore 64 emulator in this emulated DOS environment. Finally, we will run a ZX Spectrum emulator on the emulated Commodore machine.