title: Why ALU result writes address into memory for R-Type instructions?
body: <p>I'm trying to understand single-cycle datapath for MIPS instructions. Currently I can trace R-type, I-type and J-type instructions and I'm aware of control signals on different instructions but there are still unclear points in my mind. 
  In this example I assumed there is a R-type instruction let's say <code>add</code> instruction. </p>
  
  <p><a href="https://i.stack.imgur.com/46zcK.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/46zcK.png" alt="single-cycle datapath"></a></p>
  
  <p>I think <code>add</code> instruction has nothing to do with memory. Certainly it doesn't write result value to memory but it points to "Address" input in data memory. This is where I'm confused.</p>