Huh?
"It was once widely believed that bubble memory would become one of the leading memory technologies, but these promises have not been fulfilled. Other non-volatile memory types, such as EEPROM, are both faster and less expensive than bubble memory. " Webopedia
Digital busses? What are they now?
Light based transistors - Not sure what happened to this technology, but I think the next big thing will be quantum microprocessors or maybe not..........😀