Current research into the problems of cache coherency in multiprocessor (MP) systems, has primarily focused on bus based memory interconnection networks (M-ICN) and the use of various types of “snooping” cache coherency protocols. Bus bandwidth limitations can be alleviated through the use of wider bandwidth general interconnection structures, such as a crossbar switch. However, if private caches are used, the cache coherency problem becomes multiply compounded. Little work has been done to address this problem.

Basic notions pertinent to code-division multiple-user communication signals are defined in set-theoretic terms. A general treatment of composition codes by identifying a time-frequency spectrogram with a set of points in a finite plane is provided. It is shown that a finite affine plane is a powerful generator of frequency-hopping codes for multiple-access channels and that it provides optimum performance codes in a noiseless environment.>