Systems Computing Skill

Skill Metadata

skill_config:
  version: "1.0.0"
  category: systems
  prerequisites: [cs-foundations]
  estimated_time: "10-12 weeks"
  difficulty: intermediate-advanced

  parameter_validation:
    domain:
      type: string
      enum: [cpu, memory, os, network, database, distributed]
      required: true
    scale:
      type: string
      enum: [single, cluster, global]
      default: single

  retry_config:
    max_attempts: 3
    backoff_strategy: exponential
    initial_delay_ms: 500

  observability:
    log_level: INFO
    metrics: [domain_usage, design_pattern_frequency]

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Quick Start

Master how modern computers actually work, from circuits to distributed systems.

Digital Logic & CPU

CPU Concepts

• Instruction execution cycle
• Registers and cache hierarchy
• Pipelining
• Branch prediction

Cache Memory

• L1, L2, L3 hierarchy
• Temporal and spatial locality
• Cache lines and blocks

Operating Systems

Process Management

• Process states and context switching
• Scheduling algorithms: FCFS, SJF, round-robin

Memory Management

• Virtual memory and paging
• Page tables and TLB
• Page replacement: LRU, optimal

Concurrency

• Race conditions and critical sections
• Mutual exclusion: locks, semaphores
• Deadlock: conditions, detection, recovery

Networking

OSI Model

• Layer 1: Physical (signals, cables)
• Layer 2: Data Link (MAC, switching)
• Layer 3: Network (IP, routing)
• Layer 4: Transport (TCP, UDP)

Protocols

• HTTP/HTTPS: Web
• TCP: Reliable connection
• UDP: Fast connectionless
• DNS: Name resolution

Distributed Systems

CAP Theorem

• Consistency: all nodes same data
• Availability: responds to requests
• Partition tolerance: survives splits
• Can guarantee only 2 of 3

Consensus Algorithms

• Paxos: proven consensus
• Raft: simpler consensus

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Troubleshooting

Issue	Root Cause	Resolution
High latency	Slow DB queries	Add indexes, cache
Memory exhaustion	Memory leak	Profile, fix leaks
Connection exhaustion	Pool too small	Increase pool size
Cascading failure	No circuit breaker	Add circuit breakers

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Key Concepts

• Latency: Time to complete one task
• Throughput: Tasks completed per unit time
• Scalability: Performance with increasing load
• Fault tolerance: Reliability despite failures

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Interview Questions

• How do caches work?
• Explain virtual memory
• What is thrashing?
• Difference between TCP and UDP?
• How do transactions work?
• Design a system that scales to millions of users