Hard Drives

By Noah Moroze

On your computer at home, you probably have gigabytes upon gigabytes of documents and other files stored. Everything from school papers to games need to be kept, and you need a way to get them back even after you’ve turned off the computer completely. This is the job of a single component called the hard drive. When you boot up your computer, you may hear a whirring noise. This is the spinning of the hard drive’s platter, as it gathers all the information needed to start up your computer’s software.

Standard hard drives have several components. First of all is the platter, the actual spinning disk mentioned before. The platter is made out of a special material that can hold a magnetic field and store them in many different locations throughout the disk. Depending on the polarity of the field (remember how magnets have north and south poles?), the data is either read as a 0 or a 1, called a bit (more on this later).

Next is the arm that stores the data. It is able to swivel back and forth over the disk, and has a small coil that can both read the magnetic polarity of the disk, and induce (“store”) a band of magnetism. To load or store a file, your hard drive spins the platter rapidly (most at about 7,200 rpm), while the arm moves back and forth over the disk to read or write bits. Besides the platter and arm, the only other parts of a hard drive are the electronics that control the device, as well as the case which is specially sealed to prevent dust from entering.

This image of the inside of a hard drive shows the platter (the large reflective disk), as well as the arm that stores the data. Photo credit to howstuffworks.com

The storage capacity of most hard drives today are measured with gigabytes. One gigabyte is equal to about a billion bytes, and a byte is equal to eight bits, or eight 1s or 0s.  8 billion might seem like a lot of bits, but considering each bit can only represent two values, many are needed to create a significant file. Our team name is actually a play on computer storage – 2 bits and a byte is equal to 10 bits,  due to our original team size of 10 members. There are also other denominations of storage, such as the mega or kilobyte. These are just based on the prefix of the unit, so a megabyte is about a million bytes while a kilobyte is about a thousand bytes.

A new hard drive technology you may have heard about is the solid state drive. Solid state drives actually don’t use spinning disks or any moving pieces at all – they store data with special circuits that retain information without any power! The lack of moving pieces make them read and write data extremely fast, so devices using solid state drives boot up in seconds and save files nearly instantly. Also, they are less likely to be damaged by a drop and are much quieter. However, the key problem with solid state drives is the cost. They are significantly more expensive than regular hard drives, but as time moves on they are dropping in price. Pretty soon, the majority of new computers may be equipped with SSDs!


Posted in How Things Work