State two reasons why computers have more RAM than cache memory.
How to approach this question
Think about the properties of RAM and cache. Consider their cost, speed, and physical characteristics. Why would it be impractical or unnecessary to have a large amount of cache?
Full Answer
Computers are designed with a memory hierarchy to balance speed, cost, and capacity. There are two main reasons why the amount of RAM is much larger than the amount of cache memory:
1. **Cost:** Cache memory is made from a type of memory called Static RAM (SRAM), which is much faster but also much more complex and expensive to produce than the Dynamic RAM (DRAM) used for main memory. Equipping a computer with a large amount of cache would make it prohibitively expensive.
2. **Physical Proximity to CPU:** Cache memory needs to be extremely fast, so it is located very close to or directly on the CPU chip. There is limited physical space on the CPU, which restricts the amount of cache that can be included. RAM is located on the motherboard, where there is much more physical space available.
Common mistakes
✗ Stating that RAM is non-volatile (it is volatile).
✗ Simply stating "cache is faster" without explaining how that relates to why there is less of it (e.g., by linking speed to cost).
✗ Confusing RAM and ROM.
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