Modern Memory Technologies

Modern Memory Technologies

Modern Memory Technologies

Modern Memory Technologies

10 Pages

English

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1. Memory Hierarchy as a Latency Ladder

2. Registers and Caches Near the CPU

3. SRAM Cell Fundamentals

4. How SRAM Reads and Writes

5. DRAM Cell Fundamentals

6. DRAM Refresh and Access Timing

7. DRAM as Main Memory

8. NAND Flash Cell Fundamentals

9. NAND Programming, Erasing, and Wear

10. Comparing SRAM, DRAM, and NAND

1. Memory Hierarchy as a Latency Ladder

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Why not build all memory from SRAM?

Why does hierarchy improve performance?

Registers:

Cache:

Main memory:

Storage:

Registers:

Cache:

Main memory:

Storage:

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2. Registers and Caches Near the CPU

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Why do caches move whole lines instead of single bytes?

Can cache ever hurt performance?

L1 cache:

Cache line:

Tag:

Miss penalty:

L1 cache:

Cache line:

Tag:

Miss penalty:

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3. SRAM Cell Fundamentals

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Why is SRAM called static?

Does SRAM retain data when power is off?

6T SRAM:

Cross-coupled inverters:

Wordline:

Bitline:

6T SRAM:

Cross-coupled inverters:

Wordline:

Bitline:

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4. How SRAM Reads and Writes

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Why are SRAM reads not completely trivial?

What limits SRAM cache size?

Precharge:

Sense amplifier:

Write driver:

Associativity:

Precharge:

Sense amplifier:

Write driver:

Associativity:

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5. DRAM Cell Fundamentals

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Why is DRAM cheaper per bit than SRAM?

Is DRAM persistent?

1T1C cell:

Capacitor:

Leakage:

Refresh:

1T1C cell:

Capacitor:

Leakage:

Refresh:

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6. DRAM Refresh and Access Timing

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Why does temperature affect DRAM refresh?

Why are row hits faster than row misses?

Row buffer:

Bank:

Precharge:

CAS latency:

Row buffer:

Bank:

Precharge:

CAS latency:

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7. DRAM as Main Memory

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Why does adding DRAM often improve performance?

Is bandwidth the same as latency?

Virtual memory:

Page table:

DDR:

Bandwidth:

Virtual memory:

Page table:

DDR:

Bandwidth:

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8. NAND Flash Cell Fundamentals

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Why is NAND persistent?

Why can’t NAND be overwritten like DRAM?

Floating gate:

Charge trap:

Threshold voltage:

Page:

Floating gate:

Charge trap:

Threshold voltage:

Page:

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9. NAND Programming, Erasing, and Wear

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Why do SSDs need spare capacity?

What is write amplification?

Program-erase cycle:

Garbage collection:

Wear leveling:

ECC:

Program-erase cycle:

Garbage collection:

Wear leveling:

ECC:

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10. Comparing SRAM, DRAM, and NAND

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Which memory technology is best overall?

Why do computers still need both DRAM and NAND?

Volatile memory:

Nonvolatile memory:

Endurance:

Density:

Volatile memory:

Nonvolatile memory:

Endurance:

Density:

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