1. The telephone was invented by American A.G. Bell in 1876. He used two wires to connect two transmitters and receivers with the same structure and a diaphragm on the electromagnet to realize the communication between the two ends first. But the call distance is short and the efficiency is low.

Carbon microphone appeared in 1878, which greatly improved the efficiency of telephone microphone. The receiver structure has also been improved. The earliest telephone was a magnet telephone, which was powered by its own battery and sent a call signal with a hand-cranked generator. In 1880, the ordinary telephone appeared, and the power supply was centralized by the ordinary exchange, which saved the hand-broadcast generator and dry battery.

189 1 year, rotary dial-up automatic telephone appeared, which can send out DC dial-up pulse, control the action of automatic exchange, select the called user and automatically complete the transfer function.

Thus pushing telephone communication to a new stage. By the end of 1960s, push-button all-electronic telephone appeared.

In addition to pulse signaling, DTMF signaling also appeared. With the development of program-controlled switches, the dual-tone telephone is gradually popularized. Electronic telephone circuits are moving towards integration.

From 1998 to 2000, many companies claimed that they were the first to invent USB flash drives.

2. Including China Netac Technology, Israeli M-Systems and Singapore Trek Company.

However, the real patent for the basic invention of U disk is China Netac.

In July, 2002, Netac's "Electronic External Storage Method and Device of Flash Memory for Data Processing System" (patent number: ZL99 1 17225.7) was officially authorized by China National Intellectual Property Administration, which filled the gap of invention patent in the field of computer storage in China for 20 years.

The acquisition of this patent right caused a great shock to the entire storage industry, including the Israeli M-Systems Company immediately filed an invalid reexamination with China National Intellectual Property Administration, China, which once became a patent dispute that shocked China and foreign countries in the global flash memory field.

However, on February 7, 2004, 65438, Netac obtained the basic invention patent of flash disk officially authorized by the US National Patent Office, with the US patent number of US6829672.