Novel data-driven and demand-driven computer architectures are under development in a large number of laboratories in the United States, Japan, and Europe. These computers are not based on the tradlUonal von Neumann organization; instead, they are attempts to identify the next generation of computer. Basmally, m data-driven (e.g., data-flow) computers the availability of operands triggers the execution of the operation to be performed on them, whereas in demand-driven (e.g, reduction) computers the reqmrement for a result triggers the operation that will generate it. Although there are these two distinct areas of research, each laboratory has developed its own mdlvxdual model of computation, stored program representation, and machine organization. Across this spectrum of designs there m, however, a significant sharing of concepts. The aim of this palaer m to identify the concepts and relationships that exist both within and between the two areas of research. It does thin by examlmng data-driven and demand-driven architecture at three levels, computation organizatmn, (stored) program organization, and machine organLzation. Finally, a survey of various novel computer architectures under development is given.