1. A looped, unidirectional data and address communication bus apparatus in communication with a computing module for transferring data and executable control signals with respect to a plurality of instructions executing in overlapped mode, the apparatus comprising: first unidirectional bus means for selectively communicating address and data signals from said computing module to a plurality of input/output and storage devices; second bus means unidirectional with respect to said computing module for selectively communicating data and executable control signals to said computing module from said plurality of devices; third bus means for communicating address signals from said computing module; first storage means in bidirectional connection with said second bus means and responsive to first address signals on said first bus means for selectively loading or receiving data signals on said second bus means; second storage means responsive to second address signals on said third bus means for loading data signals received from said first bus means onto said second bus means; third storage means responsive to third address signals on said first bus means for loading said executable control signals onto said second bus means; and timing and control means connected to said computing module and said first, second, and third storage means and establishing respective portions of present and subsequent instruction execution cycles for loading said third address signals from said computing module onto said first bus means for addressing in said third storage means executable control signals with respect to said subsequent instruction for communication by said second bus means to said computing module, and thereafter for loading with respect to said present instruction said first address signals from said computing module onto said first bus means for addressing in said first storage means the location into which data signals are to be communicated selectively from a device or from said second storage means over said second bus means; whereby the execution of said present and subsequent instructions is overlapped.