Semiconductor device capable of holding signals independent of the pulse

Abstract

A semiconductor device and a computer system, incorporating the same, is capable of capturing an external signal at a high speed and stably operating independent of the duty ratio of a clock signal. An external signal ADD is captured into an address latch 22 by a level latch. The level latch is controlled to a through state at the timing in which the external signal is decided and controlled to a latched state in the decision period of the external signal. A pulse generation circuit controls the timing for switching a latch to the through state to a desired timing by a pulse generation circuit 30 in a chip. According to the above structure, the capture of the external signal ADD can be accelerated because the capture of the signal is determined by the setup timing. Moreover, because a latching period is controlled by the pulse generation circuit in the chip, operations are performed in a stable manner without having to depend upon the pulse width of an external clock CLK.