In processor cache hierarchy terminology, L1 is known as which type of cache?

Introduction / Context:
Modern CPUs use a hierarchy of on-chip caches to bridge the speed gap between processor cores and main memory. L1, L2, and L3 are common levels. This question asks you to correctly identify how L1 is referred to in that hierarchy.

Given Data / Assumptions:

• L1 sits closest to the CPU core.
• Cache is implemented using SRAM cells, not DRAM.
• Naming reflects proximity and latency.

Concept / Approach:
L1 cache is the first-level cache with the lowest latency and highest bandwidth to the core. It is commonly called the primary cache. L2 is the secondary cache, and L3 is often a last-level shared cache. While physically implemented using SRAM, the term sought by the question is the hierarchical role, not the circuit technology.

Step-by-Step Solution:
Identify the level closest to the core: L1.Map level to terminology: L1 → primary cache.Confirm that L2 → secondary; L3 → last-level in many designs.

Verification / Alternative check:
CPU documentation lists L1 I-cache and L1 D-cache as the primary caches serving instruction and data fetches with minimal latency.

Why Other Options Are Wrong:
Secondary cache: corresponds to L2, not L1.DRAM: caches use SRAM for speed; DRAM is for main memory.SRAM: true technology, but the question asks what L1 is known as in the hierarchy, which is primary cache.Tertiary cache: not applicable to L1.

Common Pitfalls:
Equating cache level names with memory technologies. Level names describe hierarchy position; SRAM vs. DRAM describes implementation technology.

Final Answer:
Primary cache