title: memory allocation for 64 bit OS
body: <p>memory is divided into two parts<br/>
  1) some memory portion reserved for OS system processes<br/>
  2) remaining memory for user processes.<br/>
  32 bit  OS allocates 4GB memory for OS processes. like this how many memory space is allocated for 64 bit OS(memory space only for system processes i.e. OS processes). This question was asked me in interview</p>