ICT 0417 - Types and Components of Computer Systems

Objective: Know and understand the differences between backing storage and internal memory.

This section explores the fundamental distinction between internal memory (also known as primary memory) and backing storage (also known as secondary storage) within a computer system. Understanding this difference is crucial for comprehending how data is accessed and stored.

Internal Memory (Primary Memory)

Internal memory is the computer's main working area. It's directly accessible by the CPU and is essential for running programs and storing data that is actively being used.

• RAM (Random Access Memory): This is the primary type of internal memory. It's volatile, meaning data is lost when the power is turned off. RAM is used to hold the operating system, applications, and data that the CPU is currently processing.
• ROM (Read-Only Memory): This type of memory contains instructions that the computer needs to start up (e.g., the BIOS). It's non-volatile, meaning the data remains even when the power is off. Data in ROM is typically written during manufacturing and cannot be easily changed.

Backing Storage (Secondary Memory)

Backing storage is used for long-term storage of data and programs. It's non-volatile, meaning data is retained even when the power is off. Data needs to be transferred to internal memory before the CPU can access it.

• Hard Disk Drive (HDD): A traditional type of backing storage that uses magnetic platters to store data. HDDs are relatively inexpensive and offer large storage capacities.
• Solid State Drive (SSD): A newer type of backing storage that uses flash memory to store data. SSDs are faster, more durable, and consume less power than HDDs.
• USB Flash Drives: Portable solid-state storage devices that connect to the computer via a USB port.
• SD Cards: Small, removable flash memory cards commonly used in cameras, mobile phones, and other portable devices.
• Optical Discs (CDs, DVDs, Blu-ray Discs): Data is stored on these discs using lasers. While less common now, they are still used for software distribution and data archiving.

Key Differences: Internal Memory vs. Backing Storage

The following table summarizes the key differences between internal memory and backing storage:

Feature	Internal Memory (Primary)	Backing Storage (Secondary)
Volatility	Volatile (data lost when power off)	Non-volatile (data retained when power off)
Access Speed	Fast (CPU can access directly)	Slower (data needs to be loaded into internal memory)
Cost	More expensive per unit of storage	Less expensive per unit of storage
Typical Use	Running programs, storing active data	Long-term storage of data and programs

Suggested diagram: A diagram showing a computer system with internal memory (RAM) connected to the CPU and backing storage (HDD/SSD) connected via a data bus. Label the components clearly.