Memory technologies and typical roles in a computer — match each memory type to how it is used List I (Type of memory) A. DRAM B. SRAM C. Parallel-access registers D. ROM List II (Used as) 1. Cache memory 2. Main memory 3. BIOS / firmware storage 4. CPU registers

Introduction / Context:
Computer memory hierarchy balances speed, cost, and volatility. This match connects common memory types with their canonical roles in mainstream architectures.

Given Data / Assumptions:

• DRAM is dense and economical but slower → ideal for main memory.
• SRAM is fast and expensive → used for CPU caches.
• Parallel-access registers form the CPU’s fastest storage at the pipeline edge.
• ROM (masked/flash/EEPROM) stores firmware such as BIOS/UEFI.

Concept / Approach:
Map technology attributes (latency, density, volatility) to architectural placement in the hierarchy: registers at the top (fastest), caches next (SRAM), DRAM as main memory, non-volatile ROM for boot firmware.

Step-by-Step Solution:

Verification / Alternative check:
Processor datasheets list L1/L2/L3 caches as SRAM; motherboard specs list DRAM capacities; firmware images reside in ROM/flash chips.

Why Other Options Are Wrong:

• Swapping DRAM and SRAM contradicts performance-cost trade-offs.
• Mapping ROM to cache or registers is nonsensical given volatility and speed requirements.

Common Pitfalls:
Assuming “ROM” always means unchangeable—modern systems use flash-based ROM, but the functional role (firmware) remains.

Final Answer:
A-2, B-1, C-4, D-3