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Tera, Giga, Mega, What? Understanding PC Storage

written by: M.S. Smith•edited by: Simon Hill•updated: 1/11/2010

PC storage is incredibly useful. However, the technical nature of it can be confusing. Storage is usually expressed in terms like gigabytes, but the jargon is rarely explained. This article will explain those terms and more.

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    Where You Live

    Computer storage has become a very important part of modern living. Computers have become responsible for storing the content of our lives. Family photos, vacation videos, address back-ups, recipe lists, music collections and so many other bits of information important to every day life can be stored on a computer.

    That, of course, forces one to think about what it means to store things on a computer. How does a computer store all of this information, and how much can they store?

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    How PC Storage Works

    Long-term computer memory is provided by a component called a hard drive. For the last decade and a half the prominent type of hard drive in personal computers was the hard disk. The hard disk drive includes one or more storage platters which spin while data is magnetically read or written by a delicate read/write head. This functionality isn't all that different from a DVD or even a record player, although obviously it is more advanced.

    However, some computers are now using a different type of hard drive called a solid state drive. These drives have no moving components. These hard drives function by changing and monitoring the charge of electrons in a flash memory chip. They then translate the charge into a reading of either 0 or 1, the basic binary code used by computers, thus allowing the storage of memory.

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    PC Storage Sizes

    Solid State Hard Drives are the latest PC Storage Technology One of the most confusing aspects of PC storage is file size. It is very easy to determine if some home movies will fit in a cabinet. They are simply placed in the cabinet until the cabinet is full, a state which is easily observable. Anyone can determine that a truck full of files won't fit into a cabinet the size of a cat.

    PC storage is a bit more technical. It isn't as easy as simply picking up a file and trying to stuff it in a crack of open space. File size and available capacity are indicated by numbers combined with some technical terms such as megabyte and terabyte which describe units of PC storage. A kilobyte is the most basic unit. One thousand kilobytes is called a megabyte. One thousand megabytes is called a gigabyte. And one thousand gigabytes is called a terabyte. The scale goes further, but currently the largest PC hard drives are measured in terabytes.

    Still confused? Take this example. A high-quality photo might have a size of five megabytes (shortened to 5MB). Because one gigabyte equals one thousand megabytes, we can divide one thousand by five and find that two hundred of those 5MB photos would fit into one gigabyte of PC storage.

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    Storage Complications

    Figuring out the basic units of PC storage doesn't take too much time, particularly for those with decent math skills. It is a system which uses a nice, round number - 1000 - as its base.

    Unfortunately, this easy system isn't always so easy. In some cases 1000 actually means 1024. This is because PCs use binary code and the number 1024 is a binary multiplier. This doesn't affect hard disk drives, as these drives use magnetic storage and have no inherit binary size. However, it does affect solid state drives. What this means is that a 64GB solid state drive has an actual theoretical maximum storage capacity of 65536 megabytes rather than 64000 megabytes.

    The amount of available PC storage on a hard drive, be it either a hard disk or a solid state drive, is further complicated by the file system. The file system is information on the hard drive used to tell the hard drive how to properly store information. This means that all hard drives have a slightly lower amount of actual space available on them than what is stated on the package. For example, a 500 gigabyte hard drive will probably have 460 to 480 gigabytes of real storage space.

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    Clearing the Smoke

    Fortunately this confusion can be put aside for most users by simply paying attention to the amount of space which is stated in the operating system of a PC. It is important to remember the complications of PC storage when purchasing a new hard drive as it can prevent potential disappointment. However, once the hard drive is installed the operating system will take care of the number crunching. Windows reports space using the base of 1000 no matter what type of hard drive is used. If Windows reports that 40 gigabytes of space is available it means that 40000 megabytes of space is available.