And Sinclair’s BASIC for the ZX-80. Remember, that hardware used the Z80 RAM refresh circuitry to drive the video output. All the user computing was done during

And Sinclair’s BASIC for the ZX-80. Remember, that hardware used the Z80 RAM refresh circuitry to drive the video output. All the user computing was done during the vertical retrace interval! The technique derived from Don Lancaster’s Video Toaster. Check out Lancaster’s wicki page.