Lecture Notes: Primary Storage - RAM and ROM
Overview
- Primary Storage: Includes RAM, ROM, registers, and cache memory.
- Secondary Storage: Holds the operating system, programs, and data not in use (e.g., hard drives).
- Tertiary Storage: Used for backing up and archiving large data; not covered in detail.
Importance of Primary Storage
- Volatility:
- Most primary storage (except ROM) is volatile; data is lost when power is off.
- Secondary storage is non-volatile; retains data without power.
- Capacity:
- Primary storage has smaller capacity (measured in gigabytes).
- Secondary storage has larger capacity (measured in terabytes).
- Access Speed:
- Primary storage provides faster access times compared to secondary storage, which is crucial for CPU operations.
RAM (Random Access Memory)
- Temporary Storage:
- Holds instructions and data for programs being executed by the CPU.
- Transfers data from hard disk to RAM for faster access.
- Usage:
- Holds the operating system when the computer is running.
ROM (Read-Only Memory)
- Non-volatile Memory:
- Contains initial startup instructions (bootstrap) and firmware.
- Instructions remain even when power is off.
- Bootstrap and POST:
- ROM contains instructions for Power-On Self-Test (POST) which checks hardware components.
- Essential for loading the operating system into RAM.
CPU and Storage Interaction
- Startup Process:
- Upon power on, CPU has no instructions and relies on ROM for initial instructions.
- POST signals to components, checks functionality, and informs CPU of component existence.
- Enables loading of operating system from hard drive into RAM.
Key Points
- Primary storage is essential for system speed due to faster access times.
- ROM is crucial at startup for initializing the system and running POST.
- Understanding the roles of RAM and ROM is critical for efficient computer operation.
Note: Focus on understanding the differences between volatile and non-volatile storage, and the significance of memory hierarchy in computer systems.