External Storage

COMP1260 > Hardware

Introduction There are many different forms and functions for external storage devices. They vary in both storage space as well as in their physical properties including things like size, weight and design. With time and ever more efficient technology, external storage has also grown in speed and efficiency. This section will get you familiar with the basics of external storage, provide you with a small time-line and give some examples of common uses of external storage.

...by students As mentioned in the article, external hard drives are very effective for holding computer backup files. Not too long ago my old computer's video card fried and I was unable to see anything on my monitor. There was no way I could fix this by just getting a new monitor because that was not what was causing the problems. In any case I needed to get a new computer. But there were other complications as it was nearing the end of an academic term. A time when as you know, there are several assignments due, and one of them was on my old computer. Fortunately, I kept my old computer backed-up on an external hard drive and had been keeping it up to date. Thanks to the convenience of external storage devices, all I had to do on my new computer was plug in that external hard drive and recover all of my data. Now everything that was on my old computer was now on my new computer. Sure it's a poor quality story that is certain not to gather any pity at all from the audience, but I was glad to get my work back...don't look at me like that...

External Storage Basics

What is External Storage?

External storage can be described as any device not built into a computer system that holds user data. They come in many shapes and sizes ranging from the small plastic memory cards we use in digital cameras and cell phones, to huge brick hard-drives that can take up the same amount of space as the computer itself. Most of the time the physical size of the device represents the amount of storage capacity it has. In other words the bigger a storage device is, the more room there is to store things (and the more it costs). That makes sense. But recently storage devices have been getting smaller and yet maintain pretty large storage capacities considering their size. Take, for example, digital camera cards in comparison to old floppy discs. It is not uncommon today to see a digital camera card that can hold two Gigabytes of data in a chip no bigger than a loonie. Now compare that to a floppy disk which holds around 1.5 Megabytes of data. That's around 1350 times the storage space in a device less than half of its size, which is pretty impressive!

As far as the data itself, external devices can hold any file that can be stored in your computer's hard drive. This includes things like: mp3s, video files, text documents, powerpoint shows and much more. It's as simple as cutting and pasting from your computer to your external device. What's more, external devices provide a method of carrying these files from computer to computer. This of course is one of the main purposes of external storage. For example you can write a paper in Microsoft Word at home, and save it on a USB stick to bring it to school and work on it there. Just remember to back up your work!

Types of External Storage

There are many types of devices that store your data, but it would be best at this time to only briefly discuss three of the main methods.

First is good old fashioned magnetic film. This style of data storage was seen in old cassette tapes as well as the inside of old floppy discs. Without getting too technical, the data was stored on a plastic film coated with a magnetic substance. Your data, which the computer understands as sequences of 1's and 0's, is stored on this magnetic film and was read by a device called a "reading head". The head would scan across the magnetic film until it found the data you were looking for. Unfortunately this medium of storage is very limiting on storage capacity and was also very susceptible to data corruption.

A standard 1.44MB floppy disc.

The second method is on a hard disk. This format is very similar to magnetic film in that the data is stored magnetically on a surface that a reading head must scan across. The difference in this case is that the magnetic surface is on a rotating metal plate rather than a plastic film. This form of data storage is the most common in use today for internal devices but there are many external storage devices that use this method. For example some models of the iPod use magnetic hard disc storage. The benefits of this method are that it provides quicker access to data because both the disc and the reading head can move, and because unlike the magnetic film, these discs could be stacked on top of each other to provide multiple levels of storage space in a compact device.

The third and most recent method of storage is on flash drives. This is the most common form of storage in USB sticks as well as in many mp3 players including the smaller iPod models. Many gaming systems also make use of flash memory in the way of memory cards or removable hard-drives. In the most basic sense, flash memory works by storing the 1's and 0's that make up your data in a table of cells. Each cell holds a single 1 or 0. Your data is accessed by reading the 1's and 0's from a specific row of the table. This method, as the name "flash" implies, is a very efficient way to store and transport data. This medium has quickly replaced magnetic film devices as the most common method of storing personal data. It used to be that every computer had a floppy drive in it, but it is more reasonable on the modern computer to see several USB ports for flash discs and no floppy drive at all!

A Small History of Computing and External Storage

1752-1834 Joseph Marie Jacquard's loom - One of the mathematical computing systems that used punch cards to execute programs.
1941-1942 Howard Aiken, a Ph.D. student at Harvard University working at IBM made the Mark 1, a computing system that ran on a strip of tape with holes in it.
1951-1958 First generation of digital computing, first time using punch cards to store data externally to the computer.
1959-1963 Second generation of digital computing, first machines tho use magnetic tape (cassettes) and discs (large floppys) to store data externally.
1964-1979 Third generation, punch cards are completely phased out for magnetic tapes and discs. First computers that use magnetic hard disks internally to store data.
1979-present Fourth generation, magnetic tapes and discs being phased out for hard disks. Modern external storage technology is developed and begins to evolve.

Common Uses For External Storage

Some of the most common uses for external storage devices are as follows:

• Saving commonly used files
• Portable music and video players
• Media servers for small home networks
• Backup locations for storing important files
• Holding system restore points for computer data recovery
• Quick transportation of small files
• Memory cards for cameras and cell phones
• Saving games for video game consoles

References/Further Readings

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