3Com Corp., the Santa Clara-based networking company that recently acquired modem maker U.S. Robotics Corp., said it will probably lay off about 800 people in the next year as a result of the merger. 3Com spokeswoman Sara Powers said the company will take charges associated with the layoffs, but the amount has yet to be determined. The charges will be covered in a special merger provision to be recorded in August, so all associated charges will be taken in the company's current fiscal first quarter, which began June 1, she said. Chief Executive Eric Benhamou told employees of the job cuts July 1, Powers said. Skokie, Ill.-based U.S. Robotics and 3Com agreed to merge in February and last month closed the deal valued at $8.5 billion. 3Com stock added $1.63 to close at $49.50 on Nasdaq.