An Optical Delay Line Memory Model with E cient Algorithms

The extremely high data rates of optical computing technology (100 MWords per second and upwards) present unprecedented challenges in the dynamic memory design. An optical ber loop, used as a delay line, is the best candidate for primary, dynamic memory at this time. However, they pose special problems in the design of algorithms due to synchronization requirements between the loop data and the processor. We develop a theoretical model, which we call the loop memory model (LLM), to capture the relevant characteristics of a loop based memory. An important class of algorithms, ascend/descend { which includes algorithms for merging, sorting, DFT, matrix transposition and multiplication and data permutation { can be implemented without any time loss due to memory synchronization. We develop both sequential and parallel implementations of ascend/descend algorithms and some matrix computations. Some lower bounds are also demonstrated.