Inside the CPU & Memory
Almost every modern computer uses the von Neumann architecture: a central processing unit (CPU) linked by buses to a single main memory holding both instructions and data.
The CPU contains the control unit (fetches and decodes instructions), the arithmetic logic unit (ALU) (performs computations and logic), and registers (ultra-fast local storage).
Main memory (RAM) is a large, numbered array of bytes, each with an address. RAM is volatile (erased when power drops), vastly larger than registers, but much slower.
| Component | Primary Role | Volatility |
|---|---|---|
| Registers | Immediate CPU storage | Volatile |
| Main Memory | Program/data storage | Volatile |
| Buses | Data transport wires | N/A |
Buses & The von Neumann Trap
Buses are shared wires moving data. The address bus specifies which cell is wanted ( lines address cells), the data bus carries the byte itself, and the control bus sends signals like read or write.
Common pitfall: Believing programs and data live in separate memories. In von Neumann design they share the same main memory; a program is just data the CPU interprets as instructions.
This unification lets programs modify code, but also enables security vulnerabilities where malicious input is executed as code.