When you think of a computer, chances are good that you imagine the case; the computer as a whole. However, what would you identify as the most important part of the computer? Would you point to the motherboard? Perhaps you would say that the processor is the most important part of a computer.

While these are certainly vital aspects to an operating computer, the disk drive is just as important. Over the years, they have undergone numerous changes and have evolved considerably. The first hard disks were technically "external" devices, because they sat outside the case, contained within protective covers. However, to modern users these would hardly be considered hard drives, as their storage capacity barely reached 5MB.

The Earliest "External" Drives

The very earliest hard drives were external for all intents and purposes. This is because they were not mounted within the computer frame. These devices debuted in the late 1950s, could store 5MB of data and shipped with the first commercially available IBM systems. Over the next few decades, things did not change very much, as computer use was largely relegated to commercial interests and the home PC had yet to be invented.

Almost 30 years after the debut of those systems, IBM brought out the first gigabyte drive. This device was the size of a household refrigerator, and was a separate unit from the computer. It retailed for a whopping $40,000.

The Intervening Years

Between the debut of the personal computer and the release of what a modern consumer might recognize as an external hard drive, there were several innovations. However, most of these were strictly for internal drives, as the need for an external drive was not particularly great with early systems.

One of the first systems to make use of an external hard drive was Apple. Their computers often had drive bays that were difficult to access, and some had no hard drive within them at all. In an era where computer users started to demand safer storage for their precious data, this could not work. Therefore, Apple introduced the ProFile in 1983. It worked by connecting to a special port on the back of the Apple II. This hard drive offered 5MB of disk space, though a 10MB was offered later as an upgrade.

It was during this time that internal drives began to take on their standard form factors. In fact, the shape of the hard drive stopped changing early on with the development and standardization of IDE technology, with a size and shape that has barely changed since those early years. The most popular form factors have included 5.25", 3.5", 2.5" and 1" consumer form factors.

Additionally, any of these drives could be setup as an external drive, so long as power and data cables were able to be connected to the drive outside the computer case. Of course, these were not what most people would consider "removable media" in the sense of modern external hard drives, flash drives and other storage devices.

1998 and Beyond

The year was 1998, and a revolution was brewing in the computer industry. This was the time when the USB interface was introduced to computers. This ground-breaking technology enabled any type of device to connect directly with a computer from the outside, using the same type of interface. Previously, hard drives made use of a 40-pin connector and a power cable (internal types and most external types). However, with the advent of USB technology, this was to change.

This single technology allowed different external hard drive designs to proliferate. It also enabled the birth of other removable media, such as the flash drive (thumb drive). Of course, the first external USB drives were bulky things, due to the technology available in 1998. However, as the new century approached, technology became better and better.

As more efficient power sources and cooling solutions were developed, the size of external drives shrank. Once big and heavy, these drives have become light and small. Today, you can find myriad different sizes on the market. The most popular type (for consumers, at any rate) is a bit larger than a thick paperback book. However, these solutions are not intended to be portable. Manufacturers designed these for backup and storage where the drive stays in one place, and might hold several terabytes of data.

Portable external drives were soon to hit the market. These offered storage capacity in the hundreds of gigabytes, though they did not rival larger drives in terms of storage. Portable drives became extremely popular, particularly with those who used the drive at work and at home, as well as with students who needed their data available to them on numerous computers in different locations.

An interesting development that has coincided with the growth of home networking is the ability to store data on an external drive connected to the network. These drives must be connected to the home network router, but they do not have to be connected to a computer in order to function. The router acts as a gateway, enabling data transfer between the computers and other devices within a home and the hard drive. This is an excellent solution for homes where media is used heavily, and many drives have specific built-in servers for different media types, including iTunes, games and movies.

A Glimpse of the Future

In the future, the external hard drive is expected to assume more and more a central role in home computer use. As computing devices shrink and "tablets" and netbooks come to the fore as preferred technology, external drives will need to be available for immediate access to stored data and to provide immediate backup, as well. Integreation in networks will be a must for consumers, and as technology advances it will provide some innovative solutions. Some examples include integrated router/hard drive units, as well as central server/hard drive solutions for media and entertainment purposes.