 Surviving manufacturers are Seagate, Toshiba and Western Digital (WD) with Toshiba as the senior participant having entered the market in 1977, twenty years after IBM started the market.From beginning and into the early 1980s manufacturing was mainly by US firms in the United States at locations such as Silicon Valley, Los Angeles, Minnesota and Oklahoma City.In the 1980s US firms, beginning with Seagate, began to shift production to Singapore and then other locations in southeast Asia.