Systems, apparatuses, and methods related to extended memory communication subsystems for performing extended memory operations are described. An example apparatus can include a plurality of computing devices. Each of the computing devices can include a processing unit configured to perform an operation on a block of data, and a memory array configured as a cache for each respective processing unit. The example apparatus can further include a first communication subsystem coupled to a host and to each of the plurality of communication subsystems. The example apparatus can further include a plurality of second communication subsystems coupled to each of the plurality of computing devices. Each of the plurality of computing devices can be configured to receive a request from the host, send a command to execute at least a portion of the operation, and receive a result of performing the operation from the at least one hardware accelerator.