My existing system (built many years ago) uses two parallel ports on a DOS computer - one to output the 8 bit address (yes a max of 255) and one for the 8 bit data. I already have the circuitry built that demuxes the 8 bit address into 8 outputs with 4 bit addresses and 8 bit data. I also have 5 boxes that demux these lines into eight 8 bit ports that, in turn, control the actual lights. If I had something that would output the first 8 bits of the DMX address, the 8 bit data, and a clock pulse to indicate data ready that would be the easiest for me to implement. Of course, having all 9 bits for the address would be even better but I have lived in the 8 bit address world for so long that I can live with it! Having consecutive channels with the start and clock bit would also be just fine as I don't mind building the interface from that to my existing circuits. I just wish I had the time to build my own DMX interface from scratch but ...