Company executives said on a conference call that it still expected to remain profitable in the quarter, adding that part of the weakness came from the consolidation of two major personal computer companies, an apparent reference to Hewlett-Packard's acquisition of Compaq Computer, which closed in May.
Analysts had expected National Semiconductor to post per-share profits in the first quarter of 8 cents, on average, within a range of a profit of 3 cents to 10 cents.
Santa Clara, Calif.-based National Semiconductor, which makes chips for cell phones, flat-panel displays and other electronics devices, recorded revenue of $419.5 million in the fourth quarter and $339.3 million in the year-ago first quarter.
Analysts had forecast revenue of $441.4 million for the first quarter ending in August, according to tracking firm Thomson First Call.
When National Semiconductor reported fourth-quarter results June 6, it said it expected revenue to rise 6 percent to 8 percent from fourth-quarter levels.
National Semiconductor joined a host of other companies tied to the personal computer market that have changed guidance or said the PC market was weak. PC sales in the second quarter were weaker than the seasonal norm, and companies are now waiting for the back-to-school shopping season.
National Semiconductor has said it gets about 10 percent to 15 percent of its revenue from selling chips to the PC and PC-related industries.
Taiwan Semiconductor Manufacturing Co., the world's largest contract chipmaker, last week issued a cautious forecast and cut capital spending plans due in part to a weaker-than-expected PC market.
Intel, the world's biggest maker of processors used to power PCs, said July 16 it had not seen any indication that corporations were replacing aging PCs.
National Semiconductor said order rates, including turns orders, were lower than expected in June, particularly for PC and related peripherals, such as traditional computer monitors and flat-panel displays. Turn orders are customer orders requested for delivery in the same quarter as they were placed.
Shares of National Semiconductor fell 98 cents, or 5.4 percent, to $17.13 on the New York Stock Exchange in regular U.S. trading before the revenue warning. After the close, shares slipped to $16.