Four Decades of Computing

Most computer scientists agree that there have been four distinct paradigms or eras of computing. These are: batch, time-sharing, desktop, and network.

1. Batch Era
2. Time-Sharing Era
3. Desktop Era
4. Network Era. They can generally be classified into two main categories:
   1. shared memory,
   2. distributed memory systems.
   • The number of processors in a single machine ranged from several in a shared memory computer to hundreds of thousands in a massively parallel system.
   • Examples of parallel computers during this era include Sequent Symmetry, Intel iPSC, nCUBE, Intel Paragon, Thinking Machines (CM-2, CM-5), MsPar (MP), Fujitsu (VPP500), and others.
5. Current Trends: Clusters, Grids.