On April 3, 2008, DPA (The Association for Promotion of Digital Broadcasting-Japan) announced that there has been a total 32.71 million of DTT (ISDB-T) receiving television sets (except 1seg receivers) installed in Japan as of end of March 2008. DPA also announced the guideline documentation to manufacturers who make the DTT receiver, recorder and replay units to operate with the personal computer on April 8, 2008. This add-on unit operates on USB or PCI BUS, and went on sale in May 2008.