SPUR: A VLSI Multiprocessor Workstation

SPUR (Symbolic Processing Using RISCs) is a workstation for conducting parallel processing research. SPUR contains 6 to 12 high-performance homogeneous processors connected with a shared bus. The number of processors is large enough to permit parallel processing experiments, but small enough to allow packaging as a personal workstation. The restricted processor count also allows us to build powerful RISC processors, which include support for Lisp and IEEE floating-point, at reasonable cost. This paper presents a specification of SPUR and the results of some early architectural experiments. SPUR features include a large virtually-tagged cache, address translation without a translation buffer, LISP support with datatype tags but without microcode, multiple cache consistency in hardware, and an IEEE floating-point coprocessor without microcode.