This key facts covers The Three Types of ALU Operations within Arithmetic Logic Unit (ALU) for GCSE Computer Science. Revise Arithmetic Logic Unit (ALU) in 3.4 Computer Systems for GCSE Computer Science with 15 exam-style questions and 12 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 3 of 7 in this topic. Use this key facts to connect the idea to the wider topic before moving on to questions and flashcards.
The Three Types of ALU Operations
1. Arithmetic Operations
Mathematical calculations that produce numerical results:
- Addition (+): 5 + 3 = 8
- Subtraction (−): 10 − 4 = 6
- Multiplication (×): 6 × 7 = 42
- Division (÷): 20 ÷ 4 = 5
Real-world uses: Calculating totals in shopping carts, working out game physics, processing scientific data, rendering 3D graphics
2. Logic Operations
Boolean operations that work with True/False values:
- AND: Both inputs must be TRUE for output to be TRUE (e.g., TRUE AND TRUE = TRUE, TRUE AND FALSE = FALSE)
- OR: At least one input must be TRUE for output to be TRUE (e.g., TRUE OR FALSE = TRUE, FALSE OR FALSE = FALSE)
- NOT: Inverts the input (TRUE becomes FALSE, FALSE becomes TRUE)
- XOR (Exclusive OR): TRUE if inputs are different, FALSE if same
Real-world uses: Checking multiple conditions in IF statements, combining Boolean flags, encrypting data, validating user permissions
3. Comparison Operations
Compare two values and return True or False:
- Equal to (=): Is 5 = 5? TRUE. Is 5 = 3? FALSE
- Not equal to (≠): Is 7 ≠ 3? TRUE
- Greater than (>): Is 10 > 5? TRUE
- Less than (<): Is 3 < 8? TRUE
- Greater than or equal (≥): Is 5 ≥ 5? TRUE
- Less than or equal (≤): Is 4 ≤ 9? TRUE
Real-world uses: Age verification (age >= 18), sorting algorithms, loop conditions (while count < 10), finding minimum/maximum values
Practice questions for Arithmetic Logic Unit (ALU)
What does ALU stand for?
Explain how the role of the ALU differs from the role of the Control Unit (CU).