Computer Architecture and design 2025 kuk bsc

Short Summary Computer Architecture and Design focuses on the internal structure and functioning of a computer system. It explains how hardware components like the CPU, memory, registers, and I/O devices are organized and how they interact to execute programs efficiently. The subject covers instruction set architecture (ISA), addressing modes, data representation, ALU design, control units, memory hierarchy, and performance evaluation techniques. Understanding this subject helps students bridge the gap between hardware and software, enabling them to write optimized programs and understand system-level behavior. 🔹 Important Short Answer Questions with Solutions Q1. What is Computer Architecture? How is it different from Computer Organization? Answer: Computer Architecture refers to the logical structure of a computer system that is visible to the programmer, such as instruction set, registers, data types, and addressing modes. Computer Organization deals with the physical implementation of the architecture, including hardware components, wiring, control signals, and memory technology. Difference (in short): Architecture → What the system does Organization → How the system is built Q2. What is an Instruction Set Architecture (ISA)? Answer: An Instruction Set Architecture (ISA) is a set of instructions that a processor can execute. It acts as an interface between hardware and software. ISA includes: Instruction formats Addressing modes Registers Data types Control instructions Example: x86, ARM instruction sets. Q3. Explain the concept of Memory Hierarchy. Answer: Memory hierarchy is an arrangement of memory units based on speed, cost, and capacity. Levels (from fastest to slowest): Registers Cache Memory Main Memory (RAM) Secondary Storage (HDD/SSD) Purpose: To achieve high speed at low cost by keeping frequently used data closer to the CPU. Q4. What is an Addressing Mode? Name any four types. Answer: An addressing mode specifies how the operand (data) of an instruction is accessed. Types: Immediate Addressing – Operand is given in the instruction Direct Addressing – Address of operand is specified Indirect Addressing – Address field contains another address Register Addressing – Operand is stored in a register Benefit: Provides flexibility and efficient use of memory. Q5. What is the role of Control Unit (CU) in CPU? Answer: The Control Unit (CU) directs and coordinates all activities inside the CPU. Functions: Fetches instructions from memory Decodes instructions Generates control signals Controls execution of instructions Note: CU does not perform calculations—that is done by the ALU.