An Introduction to the Direct Emulation of Control Structures by a Parallel Microcomputer

This paper is an investigation of the organization of a parallel micro-computer designed to emulate a wide variety of sequential and parallel computers. This micro-computer allows tailoring of its control structure so that it is appropriate for the particular computer to be emulated. The control structure of this micro-computer is dynamically modified by changing the organization of its data structure for control. The micro-computer contains six primitive operators which dynamically manipulate and generate a tree type data structure for control. This data structure for control is used as a syntactic framework within which particular implementations of control concepts, such as iteration, recursion, co-routines, parallelism, interrupts, etc., can be easily expressed. The major features of the control data structure and the primitive operators are: (1) once the fixed control and data linkages among processes have been defined, they need not be rebuilt on subsequent executions of the control structure; (2) micro-programs may be written so that they execute independently of the number of physical processors present and still take advantage of available processors; (3) control structures for I/O processes, data-accessing processes, and computational processes are expressed in a single uniform framework. An emulator programmed on this micro-camputer works as an iterative two-step process similar to the process of dynamic compilation or run time macro-expansion. This dynamic compilation approach to emulation differs considerably from the conventional approach to emulation, and provides a unifying approach to the emulation of a wide variety of sequential and parallel computers.