This web-based emulator (http://www.zx81stuff.org.uk/zx81/jtyone.html http://www.zx81stuff.org.uk/zx81/jtyone.html) is pretty decent. It even simulates the disp

This web-based emulator (http://www.zx81stuff.org.uk/zx81/jtyone.html http://www.zx81stuff.org.uk/zx81/jtyone.html) is pretty decent. It even simulates the display wobbles if you put it into 'fast' mode.