Kanerva's sparse distributed memory model (SDM) was initially applied to associative memory
its application is limited for its reading-writing operation by using outer product.SDM is improved in this paper by changing its original rule of reading-writing operation and retaining its characteristics of sparse distributed memory
then a novel improved model that is similar to CMAC will be obtained
in which no block effect appear and Hashing technology is not used.Theoretical analysis and example have shown this improved model effective and reasonable.