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PRAM Variants

Restrictions of access to memory cells.

• EREW (exclusive read, exclusive write)
  • Only one access to individual memory cell at a time.
• CREW (concurrent read, exclusive write).
  • Multiple concurrent reads to a memory cell, but writes are exclusive.
• CRCW (concurrent read, concurrent write).
  • Multiple concurrent writes allowed, random value (maximum value, sum, ...) is written.

Different variants may yield different complexities of parallel algorithms.