an Entity references as follows:
A re-order buffer (ROB) is a hardware unit used in an extension to the Tomasulo algorithm to support out-of-order and speculative instruction execution. The extension forces instructions to be committed in-order. The buffer is a circular buffer (to provide a FIFO instruction ordering queue) implemented as an array/vector (which allows recording of results against instructions as they complete out of order). There are additional fields in every entry of the buffer to support the extended algorithm: