Abstract: A DDR-SDRM includes a data write section including a latch section for latching first write data at a rising edge of a data strobe signal and second write data at a falling edge of the data strobe signal, and a write buffer section for writing the first write data and the second write data at a time based on the signals generated from the data strobe signal. A read operation is conducted based on the system clock signal.

Abstract: This invention is directed to a method and apparatus to find out an optimum solution in automatic routing or automatic placement with certainty and at a high-speed to improve a routing rate, and to realize automatic routing in a high-density. To these end, a routing approach is selected in a conversational mode while routing efficiency is consulted to compose routing processing procedure so as to generate a routing program. Besides, component placement processing procedures designated according to placement control information are combined to generate the placement program. A straight line between component pins adjacent to each other is defined as a chord, a wave for maze method routing is generated from a start point toward an end point of a routing path and propagated between the chords adjacent to each other.