New global routing subsystem for CMOS gate arrays

A new global routing subsystem, the `LSIS-II Layout System´ for CMOS gate array, is presented. This subsystem consists of three new algorithms, the main purpose of which is to assign available resources evenly. The first two algorithms, called EOFCW and EOFCC, show how to arrange nets so that horizontal resources are used evenly; the third algorithm PACR helps the channel router to utilise vertical resources in the channel reasonably by reassigning some pins in the contact region and thereby eliminate the bottle-necks of the horizontal resources. The present algorithm is different from those existing because it adjusts nets by analysing usable resources and the features of nets. Moreover, using the soft interface concept of system design, this subsystem considers not only the characteristics of the placement and initial global routing but also the requirement of a detailed routing for resources. The subsystem has been implemented on Micro VAX-II. Experimental results verify that the subsystem is quite efficient