Random Access Memory (RAM)
RAM is a crucial component that temporarily stores programs and data in use, allowing the CPU to access them quickly.
🔹 Key Characteristics
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✅ Basic access time:
Time needed to access information ≈ 700 nanoseconds or less. -
✅ Capacity:
Ranges from 1 GB to 8 GB or more in modern systems. -
✅ Unit:
Measured in bytes – the smallest unit of directly accessible data.
🔹 Memory Size Units
| Term | Bit/Byte Equivalent | Typical Example |
|---|---|---|
| Bit | 0 or 1 | Binary unit |
| Byte | 8 bits | One character |
| Kilo (K) | 2¹⁰ = 1,024 bytes | ~ 1 text page |
| Mega (M) | 2²⁰ bytes | ~ 1 image |
| Giga (G) | 2³⁰ bytes | ~ 1 movie |
| Tera (T) | 2⁴⁰ bytes | ~ Entire library |
🔹 Technology and Performance
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Based on integrated circuit technology.
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Modern RAM uses DDR (Double Data Rate) technology.
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Each generation (DDR2, DDR3, DDR4, DDR5) improves speed and power efficiency.
🔹 Memory Bandwidth & Naming Convention
DDR memory is labeled like PCxxxx, where xxxx = bandwidth in MB/s.
🧮 Bandwidth calculation example (DDR):
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DDR = 64-bit memory = 8 bytes.
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With DDR effect (2 transfers per cycle):
8 bytes × 2 = 16 bytes per cycle
📌 Example: frequency = 133 MHz
➡ Bandwidth = 133 × 16 × 10⁶ = 2128 MB/s
➡ Commercial name = PC2100