What is an External Storage Device?
Since the advent of computers, there has been a need to transfer data between devices and/or store them permanently. You may want to look at a file that you have created or an image that you have taken today one year later. For this, it has to be stored somewhere securely.
External storage devices of computer comprise devices that store information outside a computer. Such devices may be permanently attached to the computer, maybe removable, or may use removable media. More commonly referred to as an external drive, external storage is storage that’s not part of the internal parts of a computer.
There are many types of storage devices available in the market depending on their storage capacity, accessing time, or compatibility with an application. In this article ‘History of Computer Storage Devices – Revisiting 14 Devices’ we will take a look at different types of storage devices.
Storing data has now become an integral part of life. Experts estimate that more than 2,700,000,000,000,000,000 KB (2.7 zettabytes of data exist in the digital universe today) = 1 Billion Blu-rays.
Incredible Journey of Computer Storage Devices – Revisiting 14 Devices
Punch Cards (1890)
Punch cards (or “punched cards”) are the oldest storage devices of computer. They are also known as Hollerith cards or IBM cards, which are paper cards where holes may be punched by hand or machine to represent computer data and instructions. The punch card dates back to the 19th century when it was used to program mechanical devices such as looms and player pianos. The cards were fed into a card reader connected to a computer, which converted the sequence of holes to digital information. A typical punch card can store 0.08 KB data.
The standard punched card, originally invented by Herman Hollerith, was first used for vital statistics tabulation by the New York City Board of Health and several states. After this trial use, punched cards were adopted for use in the 1890 census.
An early computer programmer would write a program by hand, then convert the program to a series of punched cards using a punch card machine. The programmer would then take the stack of cards to a computer, and feed the cards into a card reader to input the program.
The magnetic drums were storage devices of computer as the main working memory, similar to how modern computers use random access memory (RAM) cards. In some cases, magnetic drum memory was also used for secondary storage.
It is basically a metal cylinder that is coated with a magnetic iron-oxide material where the changing magnetic polarities are used to store data on its surface, similar to how modern disk drives use magnetism to store and retrieve data. Usually, a magnetic drum has a capacity of 48 KB.
The magnetic drum was invented by Gustav Tauschek in Austria in 1932, but it was only in the 1950s to 60s that it gained widespread use as the main memory for computers, and to an extent, secondary storage. The main storage area of the magnetic drum is the metal cylinder coated with a ferromagnetic layer.
Read-write heads were positioned micrometers above the drum’s surface, along a predefined track, in order to produce an electromagnetic pulse that can be stored by changing the orientation of the magnetic particles which the read-write head is hovering over.
So as the drum rotates and the read-write heads produce electric pulses, a series of binary digits are generated. Reading was done simply by detecting which magnetic particles were polarized and which were not.
More appropriately referred to as the Williams-Kilburn tube, the Williams tubes are storage devices of computer that used CRT(cathode ray tubes) that were used with early computers. An application for a patent was originally filed by Freddie Williams on December 11, 1946, and it was finished by Freddie Williams and Tom Kilburn. The tube stored only 128, 40-bit words as an electrical charge that created a spot of light on the face of the “TV tube.”
It is considered the first type of electronic memory. A single used to store 0.128 KB of data. You’d need at least 72 of them to store a single JPG image file.
The device was 16 ½ inches long, 6 inches wide, and stored data by displaying a grid of dots on cathode ray tubes and sending a static charge through the tubes. While the technology was revolutionary, its use was not long-lived, as superior technology was developed shortly after. It remains practically unknown today.
Magnetic Tape Drive(1951)
Magnetic tapes were the first magnetic storage devices of computer. A magnetic tape drive is a storage device that makes use of magnetic tape as a medium for storage.
It uses a long strip of narrow plastic film with tapes of a thin magnetizable coating. It is essentially a device that records or perhaps plays back video and audio using magnetic tape, examples of which are tape recorders and videotape recorders.
Invented in Germany in 1928, magnetic tape was first used to store data in 1951 on the Eckert-Mauchly UNIVAC I. Tape drives used motors to wind the magnetic tape from reel to reel, while passing a tape head to read, write, or erase data.
More compact versions of this technology were common through the 1980s, like the VHS and cassette tape. Magnetic tape is used less and less for daily backups, but because of its inexpensive nature, it is still used for archiving data today.
The tapes are usually stored on cartridges or cassettes, but for drives that are used as data storage tape backups, the tape is often wound on reels. Magnetic tape is not the densest data storage medium, but as of 2010 the record for the largest data capacity in the magnetic tape was 29.5GB per square inch and the Linear Tape-Open (LTO) supported continuous data transfer rates up to 140 MB/s which was comparable to most hard disks drives.
A tape drive is only able to move the tape in a single direction and hence can only provide sequential access storage, unlike a disk drive which may provide random access as well as sequential access.
The magnetic core became the new standard in storage devices of computer. The first core memory used in a computer stored a little more than 2 KB, roughly the size of a small PNG image file or 2,000 characters of text.
Invented in 1951, magnetic core memory was first used in the MIT Whirlwind computer. Core memory works by storing one bit of data on tiny magnetic rings, or cores. The more magnetic cores you pack into core memory, the more data you can store on it.
Core memory was the standard in computing from 1955 to 1975. As recently as 2004, a magnetic core memory system was found still in service in a telephony control system. It continues to capture the interest of modern enthusiasts today.
Hard Disk Drive(1956)
The hard disks are the most common storage devices of computer even today. The HDD, first introduced by IBM in 1956, weighed over a ton and was the size of a refrigerator. The HDD stores data on one or more rapidly rotating magnetic metal platters, or disks. The HDD is still ubiquitous today, with portable models becoming smaller, with higher storage capacity, every year. It is undoubtedly the highest-capacity hard drive on the market today.
With 3.75 MB of storage, the first HDDs had enough storage space to hold a whole mp3 file, 45 seconds of low-resolution video, or 5 million characters of text.
A hard disk contains a stack of platters, circular metal disks that are mounted inside the hard disk drive and coated with magnetic material, sealed in a metal case or unit. Fixed in a horizontal or vertical position, the hard disk has electromagnetic read or write heads above and below the platters.
The surface of the disk consists of a number of concentric rings called tracks; each of these tracks has smaller partitions called disk blocks. The size of each disk block is 512 bytes (0.5 KB). The track numbering starts with zero. When the platter rotates, the heads record data in tracks. A 3.5-inch hard disk can contain about a thousand tracks.
The spindle holds the platters in a fixed position such that it is feasible for the read/write arms to get the data on the disks. These platters rotate at a constant speed while the drive head, positioned close to the center of the disk, reads the data slowly from the surface of the disk compared to the outer edges of the disk.
To maintain the integrity of data, the head is reading at a particular period of time from any drive head position. The tracks at the outer edges of the disk have less densely populated sectors compared to the tracks close to the center of the disk.
The disk fills the space based on a standard plan. One side of the first platter contains space, reserved for hardware track-positioning information that is not available to the operating system. The disk controller uses the track-positioning information to place the drive heads in the correct sector position.
The hard disk records the data using the zoned bit recording technique, also known as multiple zone recording. This method combines the areas on the hard disk together as zones, depending on the distance from the center of the disk. A zone contains a certain number of sectors per track.
Floppy disks were very common storage devices of computer till the 1990s. A floppy disk or floppy diskette (sometimes casually referred to as a floppy or diskette) is a type of disk storage composed of a thin and flexible disk of a magnetic storage medium in a square or nearly square plastic enclosure lined with a fabric that removes dust particles from the spinning disk. Floppy disks are read from and written to by a floppy disk drive (FDD).
The floppy disk was developed at IBM’s San Jose laboratory in 1967. Originally, floppy disks were uncovered magnetic disks, hence the “flop.” Later, plastic envelopes were added to protect from dirt and scratches and varying sizes of the disk emerged.
The first floppy disks, invented and made by IBM, had a disk diameter of 8 inches (203 mm). Subsequently, 5 ¼ – inch (133 mm) and then 3 ½ – inch (90 mm) became a ubiquitous form of data storage and transfer into the first years of the 21st century. By 2006, however, computers were rarely manufactured with installed floppy disk drives; 3 ½ – inch floppy disks can still be used with an external USB floppy disk drive.
IBM started using the 720 KB double-density 3 ½ – inch micro floppy disk on its Convertible laptop computer in 1986 and the 1.44 MB high-density version with the PS/2 line in 1987.
The first highly portable optical storage devices of computer. CDs had a capacity of 650 – 700 MB. That could hold 70,000 formatted .doc files, 140 minutes of low-resolution video, or, more.
The Compact Disc was developed in 1982 by both Sony and Phillips. Although the CD was only 12 centimeters in diameter, when first introduced, the CD could hold more data than a personal computer’s hard drive. CD drives read the data stored on discs by shining a focused laser beam at the surface of the disc.
CDs revolutionalized the music industry in the 1980s, eventually replacing the vinyl record and cassette tape. The sale of CDs has been eclipsed by digital music in recent years, but still, sell by the tens of millions every year.
Data is stored on the disc as a series of microscopic indentations. A laser is shone onto the reflective surface of the disc to read the pattern of pits and lands (“pits”, with the gaps between them, referred to as “lands”).
Because the depth of the pits is approximately one-quarter to one-sixth of the wavelength of the laser light used to read the disc, the reflected beam’s phase is shifted in relation to the incoming beam, causing destructive interference and reducing the reflected beam’s intensity. This is converted into binary data.
The Zip drive is a removable floppy disk storage system that was introduced by lomega in late 1994. Considered medium-to-high capacity at the time of its release, Zip disks were originally launched with capacities of 100 MB, then 250 MB, and finally 750 MB.
The format became the most popular of the super-floppy products which filled a niche in the late 1990s portable storage market. However, it was never popular enough to replace the 3 ½ – inch floppy disk. Zip drives fell out of favor for mass portable storage during the early 2000s. The Zip brand later covered internal and external CD writers known as Zip-650 or Zip-CD, which have no relation to the Zip drive.
Digital Video Disk(1995)
DVD began the era of digital storage devices of computer. DVD (abbreviation for Digital Video Disc or Digital Versatile Disc) is a digital optical disc data storage format invented and developed in 1995 and released in late 1996. The medium can store any kind of digital data and be widely used for software and other computer files as well as video programs watched using DVD players. DVDs offer higher storage capacity than compact discs while having the same dimensions.
The first DVD had 1.46 GB of storage, big enough to hold a short movie or 2 CDs. Some manufacturers make dual-sided, single-layer discs that can hold 9.4 GB of data.
Prerecorded DVDs are mass-produced using molding machines that physically stamp data onto the DVD. Such discs are a form of DVD-ROM because data can only be read and not written or erased. Blank recordable DVD disks (DVD-R and DVD+T) can be recorded once using a DVD recorder and then function as a DVD-ROM. Rewritable DVDs (DVD-RW, DVD+RW, and DVD-RAM) can be recorded and erased many times.
DVDs are used in DVD-Video consumer digital video format and in DVD-Audio consumer digital audio format as well as for authoring DVD discs written in a special AVCHD format to hold high definition material (often in conjunction with AVCHD format camcorders). DVDs containing other types of information may be referred to as DVD data discs.
Secure Digital, officially abbreviated as SD, is a proprietary non-volatile memory card format developed by the SD Association (SDA) for use in portable devices.
The standard was introduced in August 1999 by joint efforts between SanDisk, Panasonic (Matsushita), and Toshiba as an improvement over MultiMedia Cards (MMCs), and has become the industry standard. The three companies formed SD-3C, LLC, a company that licenses and enforces intellectual property rights associated with SD memory cards and SD host and ancillary products.
The companies also formed the SD Association (SDA), a non-profit organization, in January 2000 to promote and create SD Card standards. SDA today has about 1,000 member companies. The SDA uses several trademarked logos owned and licensed by SD-3C to enforce compliance with its specifications and assure users of compatibility.
Size matters not. Unless you’re getting smaller, more portable data storage, that is. The first SD cards held around 64MB, enough to hold 50 photos or 13 minutes of low-resolution video which is around 1/11 of a CD. The highest capacity of an SD card today is 1 terabyte.
USB Flash Drive(1999)
M-Systems, an Israeli company, developed the USB Flash Drive in 1999. The drive of many names. The first flash drive developed held 8 MB. It is colloquially known as a thumb drive, pen drive, jump drive, disk key, disk on key, flash drive, or a memory stick.
Similar to SD cards, USB flash drives use flash memory. USB flash drives became popular as portable storage devices due to the convenience of plugging them into a computer’s USB port for data transfer.
A USB flash drive is a data storage device that includes flash memory with an integrated USB interface. It is typically removable, rewritable, and much smaller than an optical disc. Most weigh less than 30 g (1 oz). Since first appearing on the market in late 2000, as with virtually all other computer memory devices, storage capacities have risen while prices have dropped.
As of March 2016, flash drives with anywhere from 8 to 256 GB were frequently sold, while 512 GB and 1 terabyte units were less frequent. As of 2018, 2 TB flash drives were the largest available in terms of storage capacity. Some allow up to 100,000 write/erase cycles, depending on the exact type of memory chip used, and are thought to last between 10 and 100 years under normal circumstances (shelf storage time).
Blu-Ray Optical Disc(2003)
This high definition disc supported and stored 25 GB of high definition video at 1080p, which is around 36 CDs. Sony has cranked up optical disc storage to 3.3 terabytes today.
Intended to be the successor to the DVD, the Blu-ray optical disc was developed by a technology industry consortium. While older DVDs were only capable of 480p resolution, the Blu-ray swooped in with more than double the capacity. The name was derived from the relatively short wavelength blue laser capable of reading a higher density of data on the disc as opposed to the red laser used for reading DVDs.
Cloud Data Storage(2006)
Your data is in the ether. Cloud Data Storage changed the concept of storage devices of computer. Now, your storage capacity depends only on the plan you can pay for. The options are endless.
The first all web-based data storage system was PersonaLink Services, launched by AT&T in 1994. Amazon Web Services launched AWS S3 in 2006, in part starting the trend toward massive cloud data storage. With cloud storage, remote databases are used to store information, made accessible at any time via internet access. As cloud technologies improve, cloud storage will become less and less expensive.
Cloud storage is a model of computer data storage in which the digital data is stored in logical pools, said to be on “the cloud”. The physical storage spans multiple servers (sometimes in multiple locations), and the physical environment is typically owned and managed by a hosting company.
These cloud storage providers are responsible for keeping the data available and accessible, and the physical environment protected and running. People and organizations buy or lease storage capacity from the providers to store user, organization, or application data.
Cloud storage services may be accessed through a co-located cloud computing service, a web service application programming interface (API), or by applications that utilize the API, such as cloud desktop storage, a cloud storage gateway, or Web-based content management systems.