title: Storing and retrieving process control block
body: <p>When a process is in execution, the contents of the <em>PCB</em> (which is in kernel memory space?) are loaded onto the CPU registers, and <em>status registers</em>, <em>kernel stack pointers</em>, <em>user stack pointers</em>, etc. </p>
  
  <p>When there is a context switch to another process, the current "context" is stored back in the PCB and a switch is made to the new PCB.</p>
  
  <p>Now when the kernel wants to bring back this PCB back into "context", how does it find this PCB, which is in the memory now? What information helps the kernel in finding the PCB which is in memory?</p>