Control Unit and Arithmetic Logic Unit

Control Unit (CU):

The electrical system that controls the CPU's operation is called the control unit. It facilitates coordination of data transfer between registers and ALU. Like its name implies, it regulates the operation of the CPU as well as every other component of the machine, including its traffic and other aspects. The instructions kept in ROM or RAM are used to run the control unit, which aids in the operation of the entire computer. It manages all processor control signals. By managing and supplying timing signals, it directs all input and output flow, generates code for instructions from microprograms, and guides various other units as well as models. Because it regulates the computer system's general functionality and operation, it is known as the "heart" of the computer system.

All other units are under its direction, and it gives them instructions on how to operate in a proper manner and coordinate different tasks. It tells the input device to send the information and commands first to the main memory, then to the arithmetic and logic unit (ALU). The arithmetic logic unit (ALU), the memory unit, and the peripheral devices are some of the components of the computer system that are coordinated by the control unit. Additionally, it regulates the flow of data into, out of, and within the main storage in accordance with the user's program instructions. The entire monitoring of a computer system is done by the control unit. To efficiently and swiftly conduct its control functions, the control unit needs four essential components.

They are as follows:

• Decoder
• Address Register
• Instruction Register and
• Instruction Counter

Functions of Control Unit:

• It delivers instructions to the ALU for addition and multiplication.
• It sends and receives the results of various ALU operations to primary memory.
• It sends the primary memory-stored outcome to the ALU's output.

Arithmetic Logic Unit (ALU):

Arithmetic Logic Unit is the name of the component that executes mathematical and logical operations including addition, subtraction, shifting operations, and logical instructions like AND, OR, XOR, and NOT operations (ALU). A complicated and digital type of circuit called an ALU is found inside a CPU. The process controller, RAM, and I/O devices are all directly accessible to the ALU (both as input and output). The accumulated results and input operands are stored in specified locations in the ALU. For performing integer calculations, ALUs are made. Because the result is also an integer, ALUs typically do multiplication in addition to removing and adding. Some computers have two distinct units called AU and LU, which perform arithmetic computations in AU and logical operations in LU.

ALU's structure includes a variety of accumulator registers. All arithmetic and logical operations on the data are carried out by this section of the CPU. It manages all mathematical operations in arithmetic processing (such as subtraction, addition, division, and multiplication). It handles both relational and logical operations in logical processing (such as comparing larger or smaller values, true or false statements, etc i.e. compares the numerical data as well as alphabetic data). The ALU is capable of performing logical operations on both letter and number binary codes.

Several registers and adder circuits make up the ALU. A register is a type of temporary storage that keeps information and commands while they are being interpreted and carried out. Data and instructions must be put in one of the registers before being fetched from main memory for processing (of this unit).

Reference:

Ghishing, Er.Ashim. Computer Science. Kathmandu, Nepal: Benchmark , 2008.