SAN JOSE -- North American-based manufacturers of semiconductor equipment posted a 90-day moving average of $1 billion in orders in April and a book-to-bill ratio of 0.80, signaling a likely slowdown ahead, according to SEMI.

A book-to-bill of 0.80 means that $80 worth of orders were received for every $100 of product billed for the month.

The three-month average of worldwide bookings in April was $1 billion, up 1.5% above revised March figures of $988.4 million but down 37% year-on-year.

The three-month average of worldwide billings in April was $1.25 billion, down 1.6% from revised March levels and 10% from a year ago.

"A minor decrease in billings and a commensurate increase in bookings slightly raises the book-to-bill ratio," said Stanley T. Myers, president and CEO of SEMI. "However, we are in a stasis period, where we have yet to see a significant change in business for North American-based providers of new semiconductor manufacturing equipment."