@zorkiii you will find a lot of systems are a pain in the ass to get up and running , but zx spectrum is pretty strait forward. For a start I would advise you to extract the Roms from the archives, I know this helps a lot in my experience with the speccy . The fuse core in retroarch is ok but you need to bring up the on-screen virtual keyboard to input. The Sinclair research screen you mentioned is the default basic operating system when you turn on a spectrum , just like the c64 blue screen with commordore 64 basic v12. Which means the emulator has not loaded the Rom you selected.