Atmel Corp., which has operated a semiconductor manufacturing plant in Colorado Springs since 1989, passed into the history books Monday when it was acquired by Arizona-based Microchip Technology Inc. for $3.56 billion. Microchip said Monday that Atmel revenue dropped sharply in the first quarter to between $219 million and $221 million, or down more than 15 percent from the previous quarter and off more than 30 percent from the first quarter of 2015.