Question

Which of these is the fastest type of memory? (A) (B) (C) (D)

• A. Cache
• B. Hard Disk
• C. USB
• D. RAM

Answer 1

Answer:

A. Cache

Cache memory is the fastest type of memory in this list and is essential to a computer's performance.

Computer Memory Hierarchy (Fastest to Slowest)

The different types of memory form a hierarchy based on their speed, size, and cost:

1. CPU Registers (Fastest, Smallest): Located inside the CPU.

2. Cache Memory (≈ 1-10 ns access time): Located very close to, or inside, the CPU. It stores the most frequently used data and instructions to keep the CPU busy and prevent it from waiting for the slower RAM.

   • L1 Cache is the fastest and smallest.

   • L2 and L3 Caches are progressively larger and slightly slower.

3. RAM (Random Access Memory, ≈ 50-100 ns access time): The computer's main memory. It is much larger than cache but significantly slower. It holds data and programs currently being used by the CPU.

4. Hard Disk / Secondary Storage (≈ milliseconds access time): This includes Hard Disk Drives (HDD), Solid State Drives (SSD), and USB drives (which use flash memory). These are the slowest but have the largest capacity and are non-volatile (data remains when power is off).