CPU (Central Processing Unit)
This article is a definition of the CPU – including exam questions, core components, and tags.
In a Nutshell
The CPU is the heart of every computer: It executes commands, processes data, and controls essential system operations.
Compact Technical Description
The CPU typically consists of:
- Control Unit (interprets commands, coordinates data flow)
- ALU (arithmetic-logical operations)
- Registers (very fast temporary storage)
Modern CPUs are usually multi-core and have cache memory (L1/L2/L3) for performance optimization.
Performance depends, among other things, on clock frequency, architecture, cache size, and number of cores.
Exam-Relevant Key Points
- Components: control unit, ALU, registers
- Instruction cycle: Fetch → Decode → Execute (IHK-relevant)
- Registers as extremely fast temporary storage
- Cache vs. RAM
- Security aspect: speculative execution (Spectre/Meltdown) as contextual knowledge
- Multicore: more throughput, often better energy/performance ratio
Core Components
- Control Unit
- ALU
- Register Set
- Program Counter
- Instruction Register
- Bus Interface
- Cache (L1/L2/L3)
- Clock Generator
- Instruction Set
- Interrupt Control
Simple Practical Example
ADD R1, R2
- Control unit decodes the instruction
- ALU adds contents from R1 and R2
- Result is stored in R1Explanation: The instruction cycle controls execution: 1) Fetch, 2) Decode, 3) Execute.
Advantages and Disadvantages
Advantages
- Universally programmable
- High computing speed
- Parallel processing (multicore)
Disadvantages
- Heat generation at high performance
- Dependency on instruction set
- Register/on-chip memory limited
Typical Exam Questions (with Short Answer)
- Main task of the CPU? Execute commands, process data, control system.
- What components does it consist of? Control unit, ALU, registers.
- What is the program counter? Register with address of the next instruction.
- Cache vs. RAM? Cache is faster/smaller/closer to CPU.