title: cache reads and writes
body: <p>I'm reading about cache write policies, and I just want to know if I'm understanding this correctly.</p>
  
  <p>When a read results in a cache miss, it'll get that block of memory and put it in the cache. A cache write miss then would mean that the location in memory that the program wants to write into is not within the cache, correct? So I'm reading the description of <strong>write-back</strong>, which is as follows according to wikipedia:</p>
  
  <blockquote>
    <p>initially, writing is done only to the cache. The write to the backing store is postponed until the cache blocks containing the data are about to be modified/replaced by new content. </p>
  </blockquote>
  
  <p>So the only time that the memory of a cache block can be replaced is during a read, correct? And a write would simply change the data in a particular location of memory (and this would be within a cache block if it is a hit), but it would leave the actual memory locations within the block the same, correct?</p>
  
  <p>This is my understanding of it and I just want to make sure it's correct.</p>
  
  <p>Edit: wait, I guess during a cache miss it will also be replacing/updating the cache blocks....</p>