HDMI output would have been the main display improvement but given where a PPU or a VDP sits in these architectures, you could do a lot of fun stuff including r

HDMI output would have been the main display improvement but given where a PPU or a VDP sits in these architectures, you could do a lot of fun stuff including running your own CPU core on the FPGA. (Edited - thought there was a wait pin from the PPU to the CPU but looks like it's an interrupt)