Now that you understand the basics of how the computer starts up and uses instructions in the CPU to do the things you want to do with the computer it's time to talk about what some of the different devices work. When computers first were built the problem they encountered was how to save their data. They needed a way to save the one's a zero's (capacitors with charges or no charges) after the power is turned off. After considerable thought and experimentation they found that a magnet was the perfect way to store the one's and zeros since it had two states that could be manipulated. Either it could be magnetized (have a magnetic field - one) or not be magnetized (have no magnetic field - zero). That is called magnetic storage and we use that type of storage in hard drives, floppy disc drives, and magnetic tape drives. In each of the devices there's a head that is placed very close to the medium (magnetic materiel) as the medium passes by the head if the head passes over a magnetic field a charge is sent down the wire into a capacitor in RAM where it is trapped and represents a one. If there's no magnetic field, then no charge is sent down the wire to RAM, the capacitor does not receive a charge so it remains empty representing a zero. The opposite happens when we save a file we are working on in RAM. A charge stored in a capacitor in ram representing a one is send down the wire to the head. The head then magnetizes the sector which stores a one.
Magnetic was fine for awhile but it had some problems. One, floppy disks didn't hold enough data. Second, it was difficult to use it to transfer data from one person to another. Another medium was developed to solve these problems and it was called Optical Storage. We know this type of storage as CDs and DVDs. Simply put, they are pieces of plastic with a special coating to protect the surface. On the surface are pits that represent ones. When it's being read, laser light is shined at the surface of the disc. If the light hits a pit, it is reflected to a head that send electricity down a wire to a capacitor in RAM. If the light reflects off an area without a pit (a zero) then the head doesn't get hit with the laser, no electricity goes down the wire, and nothing is store in the capacitor in RAM (a zero). The only difference between a cd, DVD, and BlueRay DVD is the number or density of the pits. The more pits we can place on the plastic the more data that can be stored.
Optical was fine but we really needed a medium that was as portable as a floppy disk with the permanence of an optical disc. That brings us to the third type of medium we can use for storage and that is solid state storage (USB, thumb, stick, etc drives). This type of storage is completely different from the first two. It uses a special type of capacitor that does not lose it's charge when power is removed. Since capacitors are so small you can fit alot in a small area. That's why our stick drives are so tiny yet can hold a lot of data. Many times more data than our hard drives from just 10 years ago. Gee, you are wondering, why not use that type of storage for RAM, Registers, and CMOS. Well, right now, it's a matter of cost and speed. In the future though we'll see these types of capacitors in our computer as combination of RAM and hard drive. No moving parts, no loss after the power turns off means that we won't turn off our computer, just the monitor because the rest of it won't use electric when we aren't doing any with the computer. Pretty cool. No more "booting' the computer and when you turn on your monitor your computer is exactly where you left it.....sweet!