Associative cache features
  Any line from memory can be placed in any line in cache.

  The segment ID and line ID become a single tag. 
    and Tag field must be big enough to contain both parts.

  All tags must be searched.
    Preferably in parallel or with TLB,
      translate look-aside buffer

  Not practical for large caches with many lines.

  Sometimes found on hard drives that provide on-drive buffering.
    Line length is very large and number of lines/segments in cache small.

    Commonly a whole track is cached as a "line".
    Best when cost of miss very high (Have to locate and read another 
      track off drive).