CPU Architecture and Simulator Design Deep Dive

A virtual English-language CPU Architect loop combines an assembly-code test, a broad microarchitecture oral, and C++ simulator design. Core topics include branch prediction, MOESI, caches, MSHRs, VIPT, TLB/page walks, ROB behavior, simulation models, and simulator optimization. Requirements The virtual English-language loop uses three technical rounds followed by a behavioral conversation with the hiring manager. Complete an assembly-code test. Explain modern CPU microarchitecture topics, including branch prediction, MOESI coherence, caches, MSHRs, VIPT, TLBs, page walks, and reorder buffers. Compare simulator time-advancement strategies (cycle-stepped vs. event-driven) separately from fidelity levels (cycle-accurate vs. cycle-approximate). Explain how to optimize a simulator without losing the fidelity required by its use case. Be ready to design a branch-predictor simulator module and justify its interfaces, state, update timing, and accuracy/performance trade-offs. Notes The questioning is difficult but interactive; hints are available when the reasoning is headed in a productive direction. Superficial definitions are insufficient. Each mechanism should connect to pipeline behavior, correctness, or measurable performance impact. Preparation Draw a modern out-of-order pipeline from memory and trace a branch miss, cache miss, TLB miss, and coherence transition through it. Implement a small branch-predictor simulator in C++ with deterministic traces and accuracy metrics. Build a two-axis comparison: cycle-stepped versus event-driven scheduling on one axis, cycle-accurate versus cycle-approximate fidelity on the other; evaluate speed, event ordering, debugging complexity, and accuracy. Practice reading short assembly sequences and explaining dependencies, stalls, speculation, and memory effects aloud.