 The conversion process started when the signal was sent to a high-quality 10-inch video monitor, where a conventional RCA TK-22 television camera—using the NTSC broadcast standard of 525 scanned lines interlaced at 30 fps—merely re-photographed its screen.The monitor had persistent phosphors that acted as a primitive framebuffer.An analog disk recorder, based on the Ampex HS-100 model, was used to record the first field from the camera.