1. A data processing system utilizing data flow components, such system having a processor control unit for processing microinstructions, and generating instruction signals, a control memory interconnected with said processor control unit to supply said microinstructions thereto, signal lines for interconnecting said data flow components to conduct signals for performing arithmetic and logical functions on data in said system, and interface means for interfacing the aforesaid elements to other elements in said system, said system comprising: a plurality of data flow components, each of said data flow components including data registers and arithmetic and shift logic, each of said data flow components serving as a byte-wide slice and having a carry input circuit and a carry output circuit interconnected by way of a carry bypass bus, the carry input and carry output circuits in each data flow component comprising switching circuits controllable to route carry signals to and from their respective data flow component or to bypass carry signals around said respective data flow component, a test and control logic unit for providing test and control signals pertaining to said data flow components and responsive to instruction signals from said processor control unit to initiate and control said data flow component arithmetic and logic operations, said data flow components each being responsive to instruction signals from said processor control unit to perform one or more arithmetic and logic operations, such as add, subtract, divide, multiply, (including shift) data and status testing, and comparison testing, and each data flow component being operable in the following operating modes: LB--Lowest Active Byte wherein a data flow component operates as least significant slice, HB--Highest Active Byte wherein a data flow component operates as most significant slice, CB--Central Active Byte wherein a data flow component operates as an intermediate slice between LB and HB, any position, SAB--Standalone Byte wherein a data flow component operates as a single slice independently of all other slices, NAB--Non-Active Byte wherein a data flow component is not active but, by way of said carry bypass bus, serves as a transmission link between data flow components that are active slices, a carry bus, said carry bus being connected to selected ones of said carry inputs and carry outputs of said data flow components to transfer shift and arithmetic carry information; an instruction bus for supplying instruction signals from said processor control unit simultaneously to all of said data flow components for controlling their operation; a plurality of data buses interconnected to convey full width data signals in said system among said processor control unit, said data flow components and other elements in said system, each of said data flow components serving a predetermined portion or "slice" of each data bus and the number of "slices" determining the total width of the data bus; a control bus interconnected between said processor control unit and each of said data flow components to provide signals for communication between components and for control purposes, and also to convey signals representative of test result information from individual data flow components to said processor control unit, each line of said control bus being connected to said data flow components so that it can be activated by any component and so that its state can be sensed by any component or by the processor control unit whereby a small number of lines serves the control requirements of a large variety of commands or instructions; a slice function control bus including a set of encoded control lines interconnected to each data flow component and providing slice status signals to each data flow component responsive to status signals from said processor control unit to establish the status of each data flow component in accordance with said operating modes whereby said system can utilize said slices in: (1) multiple-slice active combined operations of all slices, (2) active standalone operation of any selected slice, (3) multiple-slice operation of any active subset of less than the total number of available slices in any combination with selected ones of said slices being non-active and serving only as a transmission link between active slices.