Wait for small applet to load. Click on the applet window with
the mouse to make it active (and able to read the keyboard).
Hit the space bar to start when you see the picture.
Playing key controls in picture below. If the screen is blank, press 0 to start.
There are no keyboard interrupts; you must hold the keys down for long
enough for the program cycle to notice it.
Thanks again to Razvan
for this particular spectrum emulator. (Wish it had sound, though.)