Implementation of asynchronous reorder buffer for asynchronous on-chip bus

Asynchronous reorder buffer (ROB) is an important component to support in-order completion of data transactions on an asynchronous on-chip bus with multiple outstanding transactions. In this paper, two asynchronous ROBs are proposed. Based on an asynchronous circular buffer with distributed control, an asynchronous ROB is proposed for asynchronous microprocessors, which solves problems of a conventional asynchronous ROB for asynchronous microprocessors. The same scheme can be used for an asynchronous on-chip bus, but its use generates some redundancy. This redundancy results from differences between two asynchronous ROB operating environments. By eliminating this redundancy, an optimized asynchronous ROB with fully distributed control is proposed for asynchronous on-chip bus. The proposed asynchronous ROB is integrated into an asynchronous on-chip bus and simulations are performed.