adapt USB to PS2!!!! ---->>>> only if the chip on the mouse are compatible with the both protocols..
when was change the SERIAL to PS2 the firsts PS2 mouses was made with a chip that support both protocols, because that, the ADAPTERS are posible for ADAPT the PLUG for made the fisical connection. A new PS2 mosue not more support SERIAL PROTOCOL then you can't use the adapters more.... The same thing for USB- PS2.... or you thing the maker change the plug for bother???
