CS-404 Computer Org. & Architecture
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28/07/2025 11:46 pm
Computers use memory to store data and instructions. This memory is divided into two main types:
1. Primary Memory (Main Memory)
This is the main working memory of a computer. It is directly accessible by the CPU and is used for temporary data storage while the system is running.
Characteristics:
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Fast and volatile
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Temporary storage (data is lost when power is off)
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Directly accessible by the CPU
Types of Primary Memory:
| Type | Description |
|---|---|
| RAM (Random Access Memory) | Stores data and programs being used. Volatile. |
| ROM (Read-Only Memory) | Stores firmware and boot information. Non-volatile. |
| Cache Memory | Very fast memory between CPU and RAM. Temporarily stores frequently used data. |
| Registers | Smallest and fastest memory inside the CPU, holding instructions/data currently being processed. |
2. Secondary Memory (Storage Memory)
This is non-volatile memory used for long-term storage of data, programs, and the operating system.
Characteristics:
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Slower than primary memory
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Permanent storage (data remains even when power is off)
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Not directly accessible by the CPU (must be loaded into RAM first)
🔹 Types of Secondary Memory:
| Type | Description |
|---|---|
| Hard Disk Drive (HDD) | Traditional spinning disk storage; large capacity. |
| Solid State Drive (SSD) | Faster, modern alternative to HDD with no moving parts. |
| Optical Discs | CDs, DVDs – mostly obsolete. |
| Flash Drives | Portable USB drives, SD cards. |
| External Drives | Additional storage connected externally via USB or other ports. |
