Control Logic Gates in Computer Architecture: Coordinating CPU Operations

Explore the design and function of control logic gates in a basic computer's control unit. This guide explains how these gates generate control signals to coordinate the CPU's various components during instruction execution. A detailed diagram is included.

Control Logic Gates in a Basic Computer

Control Logic in Computer Architecture

The control logic unit is responsible for coordinating the various components of a computer system to execute instructions. In a hardwired control unit, the control signals are generated directly from the instruction, and the control logic is implemented using combinational logic circuits (logic gates).

Control Logic Gates: Inputs

The inputs to the control logic circuit in a basic computer architecture come from several sources:

  • Operation Decoder: Provides signals indicating the operation to be performed.
  • Timing Decoder: Generates timing signals to coordinate the different stages of the instruction cycle.
  • Instruction Register (IR): Contains the instruction being executed (bits 0-11).
  • Status Register: Reflects various states of the CPU and registers.
  • Registers (AC, DR): Contain data values.
  • Flip-Flops (I, S, E, R, IEN, FGI, FGO): Store control signals and status information.

Control Logic Gates: Outputs

The outputs of the control logic circuit control the operation of various components within the computer:

  • Control signals for the nine registers (selecting registers for reading and writing).
  • Read and write signals for memory.
  • Signals to set, clear, or complement flip-flops.
  • Register selection signals (S2, S1, S0).
  • Control signals for the ALU (Arithmetic Logic Unit) and adder circuits connected to the accumulator.

Block Diagram

(A block diagram illustrating the control logic unit, its inputs and outputs, and its connection to other computer components should be included here. The diagram should reflect the information stated in the "Inputs" and "Outputs" sections above.)

Conclusion

The control logic unit plays a critical role in orchestrating the instruction cycle and managing the flow of data between the various components of a computer. Its implementation using logic gates ensures precise and efficient execution of instructions.