Apollo Computer said it laid off 300 employees.

The Chelmsford, Mass.-based supplier of computer work stations for engineering and scientific applications, said the action was part of a planned 12% reduction in its work force. The company also said it will report a loss of about $4 million from operations and take a one-time charge of $14 million for the quarter ending Sept. 28. Apollo blamed the loss on cancellations and deferrals of orders by customers.