ZX81 had a small black plastic case and was also available as a kit. It was of such simple low-cost design that it drove prices of competing computers way down, thus putting computers into the hands of millions of hobbyists and home users. In fact, early models had a ZX81 circuit board. It was released in Fall 1983, just before Timex Computer Corp folded in Spring 1984. They, of course,were only allowed to sell in non-Sinclair controlled marketplaces.
Color palette is a bit strange.
Emulates Cursor Joystick with cursor keys on keyboard and Kempston Joystick with joystick connected to Port 2 of Amiga. Needs at least 68020. Doesn't emulate R register correctly, or certain undocumented instructions. The speed is adjustable. Doesn't fully implement the R register.