Day 2 of the Computer Architecture course. L1/L2/L3 cache, DRAM, the memory wall, cache coherence, and why cache misses dominate modern performance. This lesson builds conceptual depth and hands-on practice in equal measure.
By the end of this lesson you will understand the core concepts behind memory, be able to recognize them in real code or systems, and complete the hands-on exercise that ties L1/L2/L3 cache, DRAM, the memory wall, cache coherence, and why cache misses dominate modern performance. together.
Memory is one of those topics where the gap between understanding the concept and applying it correctly is wider than it first appears. The mental model matters as much as the mechanics. Today builds both — starting with the conceptual foundation, then grounding it in working code you can run and modify.
The first step with memory is establishing the right mental model. Without it, the specifics don't connect and the details don't stick. With it, the implementation becomes almost obvious.
The key distinction most beginners miss: l1/l2/l3 cache, dram, the memory wall, cache coherence, and why cache misses dominate modern performance. Understanding that distinction before writing any code will save substantial debugging time later.
The implementation pattern for memory follows a consistent structure that appears in every real-world system. Recognizing this pattern makes unfamiliar codebases immediately more readable.
Hard-coded values, no error handling, works on the happy path. Fine for a proof of concept. Breaks immediately in production when any assumption changes.
Configuration separated from logic, error cases handled explicitly, behavior verified with tests. Takes slightly longer to write, survives contact with reality.
The hands-on exercise for this lesson takes 20–40 minutes and covers the most important mechanics from Sections 1 and 2. Complete it before moving to Day 3.
Before moving on, you should be able to answer these without looking: