register (thing)

A register is an electronic device that holds a binary number. One can be constructed from a bank of flip-flops arranged in a parallel load or serial load configuration, or both. Similarly, a register may be read from in parallel or serial, or both. An example of a simple 4-bit parallel in/parallel out register is shown here:

    Assembly:            Whole Unit:
      +---+                 +-+   
I3----|D Q|--O3             | |
    +-|>  |           I--/--|C|--/--O
    | +---+              4  | |  4
    | +---+                 | |
I2--|-|D Q|--O2             +-+
    +-|>  |
    | +---+
    | +---+
I1--|-|D Q|--O1
    +-|>  |
    | +---+
    | +---+
I0--|-|D Q|--O0
clk-+-|>  |
      +---+

The 'C' in the Whole Unit diagram is simply a name for this register and the '4' indicates that there is a 4-bit bus on both the input and output.

See also shift register (for a serial load configuration), accumulator, three-state logic, arithmetic logic unit, sequential arithmetic, D Flip-Flop, SR Flip-Flop, JK Flip-Flop.