Intel Corp.’s main personal-computer processor business is showing signs of improvement after a record industry slump, yet the company’s push to get into faster-growing mobile-phone chips has gone backward.

The world’s largest semiconductor maker yesterday reported higher first-quarter sales and forecast revenue that may top analysts’ estimates in the current period, saying the PC market is stabilizing. At the same time, Intel said the phone and tablet chip business posted a quarterly operating loss of more than $900 million as sales plunged 61 percent.