The Development of Array Architectures Embodying Partial Local Autonomy

SIMD arrays have proved very useful for low-level image processing tasks. The CLIP7 programme is seeking to extend their area of applicability to intermediateand high-level operations, particularly by increasing the amount of local autonomy for each processor in the array. This paper describes a sequence of degrees of autonomy which are used as the basis of the investigation, and a linear array of partially autonomous processors (CLIP7A) which is the first system to be built in this programme. The system embodies the ability to locally determine the neighbourhood connectivity of each element and the freedom for each element to determine addresses within the local data RAM. Some suggestions are given of algorithms which might use these facilities. processor, whilst achieving a complete understanding of the operation and application of the system at each stage. This paper addresses the first stages of this process, namely the analysis of the types of autonomy which processors in an array can embody, together with examples of the operations which each step allows to be more efficiently executed. In the following a progression from pure SIMD to complete MTMD is derived which provides a conceptual framework around which subsequent parts of the CLIP7 programme will develop. The second part of the paper describes CLIP7A, the first system which has been constructed under the Alvey programme to investigate and develop these concepts.