SINGLE - CHIP COMPUTERS, THE NEW V L S I BUILDING BLOCKS Carlo H. Sequin Computer Science Division Electrical Engineering and Computer Sciences University of California Berkeley CA 94720 ABSTRACT Current trends in the design of general purpose VLSI chips are analyzed to explore what a truly modular , general-purpose component for digital comput- ing systems might look like in the mid 1980's. It is concluded that such a com- ponent would be a complete single-chip computer, in which the hardware for effective interprocessor communication has been designed with the architecture of the overall multiprocessor system in mind. Computation and communica- tion are handled by separate processors in such a manner, that both can be per- formed simultaneously with full efficiency. This paper then describes relevant features of X .TREE, a research project which addresses the question how the power of VLSI of the next decade can best be used to build general purpose computing systems of arbitrary size. In X .TREE, a general VLSI component realizable in the mid 1980's is defined, and its interconnection into a hierarchical tree-structured network is studied. The overa ll architecture, communications issues and the blockdiagram of the modu- lar component used are discussed. 435 CALTECH CONFERENCE ON VLSI , January 1979