I'm currently reading about how the computer works, specifically how the CPU, RAM, hard disk drive work together simultaneously.
According to what I have read, the CPU uses what is called a control unit to get the data from RAM. And then processes the data.
But before the CPU can get data from RAM, the data must be loaded from the Hard Drive to RAM since access to RAM is faster than access to the Hard Drive.
My question is: Can the CPU get data directly from the Hard drive?
How does the Hard disk drive transfer data or load the data to RAM? Just as the CPU to RAM using control unit?
I have read a little about I/O disk. Has I/O disk something to do with this?