Toshiba has been contacted by investigators from the U.S. Department of Justice (DoJ) who are looking into the static RAM (SRAM) chip market, the company said Tuesday.This brings to four the number of SRAM makers that have received subpoenas or requests for assistance from the DoJ. The others are Cypress Semiconductor, Mitsubishi Electric and Samsung Electronics.SRAM is typically used as a memory buffer in devices such as computers and hard-disk drives. It can retain data as long as power is supplied. That puts it between dynamic RAM (DRAM), which retains data with power but requires refreshing, and flash memory, which retains data even when power is not supplied."Toshiba\u2019s American subsidiary, Toshiba America Electronics Components, has received a subpoena from the Department of Justice and is cooperating in what appears to be an industry-wide investigation. We refrain from commenting further," the company said in a brief statement.News of the investigation came first from Cypress, which said last week that it had been contacted by the DoJ and would be cooperating with the investigation. On Monday, both Mitsubishi Electric and Samsung Electronics said their U.S. units had been subpoenaed."Samsung will cooperate fully with the Department of Justice on this matter," spokeswoman Chris Goodhart said in a statement on Monday. "Samsung is committed to fair competition and ethical practices and forbids anti-competitive behavior."Samsung was one of several companies snared by a DoJ investigation into the DRAM market.Justice Department lawyers found evidence of price fixing by major chip makers bidding for business with big U.S. computer makers including Dell, Apple Computer, Hewlett-Packard and IBM. Several DRAM makers have been ordered to pay fines as high as US$300 million, and three Samsung executives were sentenced to time in prison for the part they played in the price fixing.-Martyn Williams, IDG News Service (Tokyo Bureau)Related Links:\n\nU.S. Expands SRAM Antitrust Probe to Samsung\n\nMitsubishi SRAM Sales Probed by DoJ\n\nSamsung Exec Pleads Guilty in DRAM CaseCheck out our CIO News Alerts and Tech Informer pages for more updated news coverage.