The interpreter
E. W. Reigel, U. Faber, David A. Fisher · 1971
Digital computing systems have traditionally been described as being composed of the five basic units: input, output, memory, arithmetic/logic, and control (see Figure 1). Machine instructions and data communicated among these units (as indicated by the solid lines in the figure) are generally well-known and understood. The control signals (as indicated by dashed lines in the figure), are generally less well-known and understood except by the system designer. These control signals generated in the control unit determine the information flow and timing of the system.