A memory device includes a plurality of memory cells, a token input interface, a token output interface and control circuitry. The control circuitry is configured to accept a storage command, to condition execution of at least a part of the storage command on a presence of a token pulse on the token input interface, to execute the storage command, including the conditioned part, in the memory cells upon reception of the token pulse on the token input interface, and to reproduce the token pulse on the token output interface upon completion of the execution.