3.1 · Lesson 2 of 7
Inside the CPU
Syllabus 3.1.1Syllabus 3.1.2Syllabus 3.1.3
What this lesson covers
- Describe the role of the CPU and a microprocessor
- Describe the components of a Von Neumann CPU
- Describe the fetch–decode–execute cycle
Key vocabulary
- CPU
- The central processing unit: processes instructions and data so the result can be output.
- Microprocessor
- A type of integrated circuit on a single chip.
- Control unit (CU)
- Decodes instructions and sends control signals to coordinate the other components.
- Arithmetic logic unit (ALU)
- Carries out calculations and logical comparisons.
- Register
- A small, very fast memory location inside the CPU.
- Program counter (PC)
- Holds the address of the next instruction to be fetched.
- Memory address register (MAR)
- Holds the address of the memory location to be read from or written to.
- Memory data register (MDR)
- Holds the data or instruction fetched from memory, or to be written to memory.
- Current instruction register (CIR)
- Holds the instruction currently being decoded and executed.
- Accumulator (ACC)
- Holds the result of calculations carried out by the ALU.
Check your learning
- Quick check: 4 questions
- Key vocabulary test: 10 terms
- Activity 1: Registers and units · 8 questions
- Activity 2: Trace a program · 6 questions
- Activity 3: CPU quiz · 8 questions
- Activity 4: Order the FDE cycle · drag and drop