Fourth Generation and Beyond

• Personal computers and workstations
• MS-DOS and Unix
• Massively parallel systems
  • Pipelining
  • Array processing / SIMD
  • General multiprocessing / MIMD
  • Symmetric multiprocessing / SMD
    • Any process and any thread can run on any available processor
• Computer networks (communication aspect) -- network operating systems
• Distributed computing -- distributed operating systems