JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech III COMPUTER ORGANIZATION AND OPERATING SYSTEMS Previous Question Paper (July - 2023 - R16)

An ALU (Arithmetic Logic Unit) is a fundamental digital circuit within a computer's Central Processing Unit (CPU) that performs all mathematical and logical operations on data. It acts as the primary computational engine of the processor, executing instructions fetched from memory.

The ALU typically performs the following operations:

• Arithmetic Operations: Basic mathematical calculations including addition, subtraction, and sometimes multiplication and division.
• Logical Operations: Bitwise operations such as AND, OR, NOT, XOR, and NAND, which are essential for decision-making and data manipulation.
• Comparison Operations: Relational operations like equal to, less than, or greater than, which generate status flags (e.g., Zero, Carry, Overflow) used by the Control Unit to manage program flow.

The ALU receives data from the CPU registers and control signals from the Control Unit, processes the input, and stores the result back into registers or memory, while updating the status register to reflect the outcome of the operation.

The basic building blocks of a computer system are essential components that facilitate the input, processing, storage, and output of data. These components are interconnected to perform computational tasks efficiently:

• Central Processing Unit (CPU): Often referred to as the brain of the computer, it performs arithmetic, logical, and control operations. It consists of the Arithmetic Logic Unit (ALU) for calculations, the Control Unit (CU) for instruction decoding and management, and Registers for high-speed temporary data storage.
• Memory Unit: This component stores data and instructions required for processing. It is categorized into Primary Memory (RAM and ROM), which provides fast access for the CPU, and Secondary Memory (such as Hard Drives or SSDs), which provides non-volatile, long-term storage.
• Input Devices: These devices allow users or external systems to provide data and control signals to the computer. Examples include keyboards, mice, and scanners.
• Output Devices: These components translate processed binary data into human-readable formats or physical actions. Examples include monitors, printers, and speakers.
• System Bus: This is the communication pathway that connects the CPU, memory, and input/output devices. It consists of the Data Bus (for transferring data), the Address Bus (for specifying memory locations), and the Control Bus (for transmitting command signals).