Abstract: A method is disclosed for analyzing a VLSI circuit design stored in a computer system. Each segment of the design layout is stored in the computer memory for analysis and implementation. An electronic computer-aided design (E-CAD) program is used to analyze the design. First, the E-CAD tool is run on the entire design or on a designated part thereof. The tool compares the design to specifications and returns a list of violations on a segment basis. The E-CAD tool identifies violations for the designer to fix through redesign or clarification of specifications. The method marks or flags signals of those segments reporting violations. After the designer has attempted to remedy the violations, the method reruns the E-CAD analysis on those signals that reported a violation during a prior run.

Abstract: A method is disclosed for analyzing a VLSI circuit design stored in a computer system. Each segment of the design layout is stored in the computer memory for analysis and implementation. An electronic computer-aided design (E-CAD) program is used to analyze the design. First, the E-CAD tool is run on the entire design or on a designated part thereof. The tool compares the design to specifications and returns a list of violations on a segment basis. The E-CAD tool identifies violations for the designer to fix through redesign or clarification of specifications. The method marks or flags signals of those segments reporting violations. After the designer has attempted to remedy the violations, the method reruns the E-CAD analysis on those signals that reported a violation during a prior run.

Abstract: A system and method is disclosed for determining the clock frequency ratio between a CPU clock and a "secondary clock," where the secondary clock controls one or more operations external to the CPU. The present invention is configured to function with a CPU which can operate interchangeably at one of two or more possible clock frequency ratios. In a preferred embodiment, a system clock generator outputs a signal SYNCH which has a frequency equal to the frequency of the secondary clock divided by an integer N. Signal CK2, having the same frequency as the CPU clock, and SYNCH, are input to a frequency ratio detector. The frequency ratio detector determines the clock frequency ratio between the CPU clock and the secondary clock, where this ratio can be only one of a discrete number of fixed values. The frequency ratio detector outputs one or more MODE bits which indicate the clock frequency ratio detected.

Abstract: A system and method for isolating the timing domain of a central processing unit (CPU) from the timing domain of a memory bus is described. The CPU interfaces with memory and input/output through a dual clock domain interface (DCDI). The DCDI allows the CPU and memory to operate at frequency ratios of N:M, where N and M are positive integers, with N greater than or equal to M. The CPU operating clock speed is not constrained by the operating speed of the memory and input/output. The primary components of the DCDI are: 1) domain translation buffers, 2) clock control circuit, 3) output data queue and 4) receiver modifier circuits. A domain translation buffer takes data from one clock domain and translates it into another clock domain. The clock control circuit generates appropriate clocks according to the current frequency ratio of the system. An output data queue is required when the CPU generates data faster than the memory can accept.