I'm not interested in 3D graphics. I'm interested in running a keyboard, a terminal of some sort, and some task switching OS. No sound or anything else needed

I'm not interested in 3D graphics. I'm interested in running a keyboard, a terminal of some sort, and some task switching OS. No sound or anything else needed. I do remember some of my (much older) friends talking about their Sinclair ZX Spectrum. From what I remember they said they had a Z80 in that. That old computer was able to do basic text editing from what I remember.