CS Computer Organization & Architecture 1 — Questions and Answers
Question 1: Which component of the CPU is responsible for performing arithmetic and logical operations?
- Arithmetic Logic Unit (ALU) (Correct answer)
- Control Unit
- Program Counter
- Memory Management Unit
Correct answer: Arithmetic Logic Unit (ALU)
The ALU is the digital circuit within the CPU that executes arithmetic (add, subtract) and logical (AND, OR, NOT) operations.
Question 2: In a von Neumann architecture, which characteristic distinguishes it from a Harvard architecture?
- Instructions and data share the same memory and bus (Correct answer)
- Instructions and data use separate memory spaces
- It uses a dedicated instruction cache
- It requires a co-processor for I/O
Correct answer: Instructions and data share the same memory and bus
Von Neumann architecture uses a single shared memory and bus for both program instructions and data, unlike Harvard architecture which uses separate paths.
Question 3: What is the primary function of the Program Counter (PC) register?
- Holds the memory address of the next instruction to fetch (Correct answer)
- Counts the total number of instructions executed
- Stores the result of the most recent ALU operation
- Tracks the number of elapsed clock cycles
Correct answer: Holds the memory address of the next instruction to fetch
The Program Counter always points to the address of the next instruction to be fetched, advancing after each fetch.
Question 4: Which type of bus is used to carry memory addresses from the CPU to RAM?
- Address bus (Correct answer)
- Data bus
- Control bus
- Expansion bus
Correct answer: Address bus
The address bus carries the memory address the CPU wants to read from or write to; it is typically unidirectional from CPU to memory.
Question 5: What does the control unit (CU) do within a CPU?
- Fetches, decodes, and directs the execution of instructions (Correct answer)
- Performs floating-point arithmetic operations
- Manages the CPU's cache hierarchy
- Handles direct memory access transfers
Correct answer: Fetches, decodes, and directs the execution of instructions
The control unit orchestrates the fetch-decode-execute cycle by generating the control signals that coordinate all other CPU components.
Question 6: Which addressing mode uses the operand value directly embedded in the instruction itself?
- Immediate addressing (Correct answer)
- Direct addressing
- Indirect addressing
- Register addressing
Correct answer: Immediate addressing
In immediate addressing, the operand is a constant value encoded within the instruction, requiring no additional memory lookup.
Question 7: What is the purpose of general-purpose registers in a CPU?
- To provide fast, on-chip storage for operands and intermediate results (Correct answer)
- To cache frequently accessed main memory pages
- To store the operating system's kernel code
- To buffer data transferred over the system bus
Correct answer: To provide fast, on-chip storage for operands and intermediate results
General-purpose registers are the fastest storage available to the CPU, used to hold operands and results during instruction execution without requiring memory accesses.
CS Computer Organization & Architecture 1
Which component of the CPU is responsible for performing arithmetic and logical operations?