Computer Architecture — From Gates to CPU

Computer Architecture — From Gates to CPU covers: Nand2Tetris, Computer System Architecture, Write Great Code Vol 2. Understand how a computer is built from the ground up: logic gates, combinational circuits, sequential circuits, ALU, CPU, memory hierarchy, pipelining, caching. Build a working computer in Nand2Tetris. When you write User.find(1), Rails generates SQL, sends it to PostgreSQL, which parses it, creates a query plan, reads from disk (or cache), and returns results. The performance of every step depends on architecture: the CPU's branch predictor guessing whether your WHERE clause will match. The L1/L2/L3 cache determining whether the index page is in cache or must be fetched from RAM. The disk controller's DMA transferring data without CPU intervention. After this module, you understand why "reading from cache is 100x faster than reading from disk" — because you know what a cache line is, what a cache miss costs, and what happens in the memory hierarchy.