Brave users of history's earliest computers programmed those massive electronic beasts through jumper wires plugged into arrays of sockets. With so few computers in existence (none of them compatible with any others), digital pioneers had little need for portable software: The programs stayed put. Soon, however, companies like IBM began selling multiple identical computers, and users sought a way to program the devices more efficiently, to move programs from computer to computer, and to reload programs later with a minimum of hassle. Thus begins the history of removable computer storage, which in many ways is the story of software distribution: The first job of removable storage was to share software without requiring any reprogramming from scratch. Over the next few pages, we'll revisit dozens of ways that engineers have solved the problem over the past 60 years.
Punched paper tape
Most of the earliest computers used spools of paper tape, which stored information via punch holes. Some early machines, like the Colossus Mark 1 (1944), operated entirely on the data fed in by the tape in real time. Later computers, like the Manchester Mark 1 (1949), read in programming from tape and stored it in a primitive type of electronic memory for later execution.
Various computers during the next three decades continued to use paper tape for both input and output, and the medium experienced a brief renaissance in the mid-1970s among personal computer hackers who were attracted to its low cost.
Punch cards trace their origins to textile looms of the 1800s, where they conveyed instructions that defined and controlled machine weaving operations. In 1890, Herman Hollerith applied the punch card idea to tabulating US Census data. He founded a company (which grew to become IBM) that used the cards in tabulating machines.
When IBM began building general-purpose computers in the 1950s, it used the cards for data storage and input, and soon many other computer manufacturers adopted punch card formats of various kinds. Many used 80-column cards, which stored one character per column. As late as 2002, IBM was still researching punch card technology, in the form of a system capable of storing 25 million pages of data on a surface the size of a postage stamp.
Data on tape
The UNIVAC I (1951) started a new trend in data storage: magnetic tape. IBM soon began using reels of magnetic tape (similar to the audio tape of the time) for computer data storage, and the rest of the industry followed suit. Computer tape, usually stored in open reels, generally consisted of thin strips of plastic coated with a magnetically sensitive substance that computers wrote to and read from by means of electronic heads embedded in a special tape drive.
Numerous production computer models (especially mainframes and minicomputers) used open-reel tape as a mass storage medium until the 1970s and 1980s, when designers switched in increasing numbers to tape cartridges.
The first removable disks
IBM introduced the first hard drive with removable disks, the IBM 1311 (shown here in the upper right image), in 1963. It used interchangeable disk packs, each composed of six 14-inch-diameter disks. Each disk pack stored about 2MB of data. Many 1970s-era hard drives, such as the DEC RK05 (a similar model appears in the image to the far left), accommodated disk packs, which minicomputer companies often used for software distribution.
In the 1960s, computer makers began placing spools of miniature magnetic tape into hard plastic cartridges. These cartridges were more durable, portable, and convenient than the larger open reels of magnetic tape, and their popularity as a backup medium for ever-growing hard disks increased in the 1970s and 1980s. Like earlier open-reel systems, the capacity of tape-cartridge systems had the advantage of flexible capacity. When storage needs increased, tape manufacturers simply created cartridges that held more tape. More tape meant more space.
Today, tape cartridges like the 800GB LTO Ultrium (lower left) remain in use for large-scale server backups, though their popularity has diminished over the last decade as hard-drive-to-hard-drive transfers have gained favour.
Printed on paper
In the 1970s, the relatively low cost of personal computers attracted home computer hobbyists to the then-new category of machines, but many forms of electronic data storage were too expensive for these users. One of the first PCs, the MITS Altair (among our choices for the most collectible PCs of all time), shipped with no storage media whatsoever; instead, users had to input programs via switches on the front panel of the computer (a program for which is shown at far upper left). Throughout the early PC days, users often wrote programs down by hand and then toggled them in. Later still, national magazines printed and distributed program listings (right) for users to type into the inexpensive home computers of the 1980s.
The floppy diskette
IBM introduced the first commercial floppy drive in 1971. It worked with 8-inch flexible disks coated with a magnetic material and permanently encased in a plastic sheath.Users quickly recognized that, for loading data into computers, floppy disks were faster, cheaper, and more space-efficient than stacks of punch cards. In 1976, the floppy's co-inventor, Alan Shugart, created a new 5.25-inch floppy drive for personal computers. That disk size remained an industry-wide standard until the latter half of 1980s, when Sony's 3.5-inch floppy format (invented in 1981) achieved marketplace dominance.
By 2002, though, people had begun to ask, "What has your floppy drive done for you lately?"
The compact cassette
Philips developed the Compact Cassette, two small reels of magnetic tape in a plastic shell, as a format for audio recordings in the 1960s. HP briefly used that format in its HP 9830 (1972), but the compact cassette didn't gain widespread popularity for digital data until a few years later, when personal computer hackers, hungry for cheap storage, commandeered the format. The medium remained popular in bargain computers of the late 1970s and early 1980s because both to the media and the drive were so inexpensive (many computers could load and save data from a standard audiocassette player).
The ROM cartridge
A ROM cartridge is a circuit board containing a read-only memory (ROM) chip and a connector encased in a rigid shell. These cartridges could be used for games or programs.
Fairchild invented the ROM software cartridge for use with its Fairchild Channel F video game system in 1976. Soon, home computers like the Atari 800 (1979) and the TI-99/4 (1979) had adopted the ROM cartridge, using it for simple software loading and distribution. Lotus even made a cartridge-based version of Lotus 1-2-3 for the IBM PCjr (1984). ROM cartridges were fast and easy to use, but they were also relatively expensive--a drawback that sealed their doom.
The great floppy experiments
Many companies tried their hand at alternative floppy formats in the 1980s. One such "floppy" (top centre) wasn't a floppy at all: The ZX Microdrive cartridge (sometimes called a "stringy floppy") contained an endless loop of magnetic tape, similar to an eight-track cassette. Other experiments include Apple's FileWare (right), included with the first Apple Lisa; the 3-inch Compact Floppy (bottom left); and the rare 2-inch LT-1 floppy (top left), used only in 1989's Zenith Minisport laptop. Other efforts appeared in niche products, but none dominated like the 5.25-inch and 3.5-inch floppy formats.
The optical disc
The compact disc, which originated as a digital audio storage medium, emerged from a joint Sony/Philips project and first reached the market in 1982. The format stores digital data in the form of pits moulded into the top of a plastic disc that has a reflective backing. A laser reads the pits. Because CDs are digital, they are perfect for storing computer data, and it wasn't long before Sony/Philips adapted the format to create computer CD-ROMs, producing the first commercial CD-ROM drive in 1985. The 12cm optical disc has undergone further development during the past 25 years, resulting in higher-capacity discs such as DVD, HD-DVD, and Blu-ray. More significant was the introduction in 1988 of the CD-Recordable (CD-R), which let users write their own data to the disc. In the late 1990s, this form of storage supplanted floppies in handling most day-to-day data transfers.
Like CDs, magneto-optical (MO) discs are designed to be read optically with a laser. But unlike CDs, which users can't write to at all, and CD-Rs, which users can write to only once, most MO discs permit the user to write and erase data on a disc multiple times. They accomplish this by means of a special magnetic process that works in conjunction with a laser to store data. The first widely known magneto-optical drive shipped with the NeXT Computer (1988, lower right) and used 256MB rewritable media. The best known MO format is the Sony MiniDisc (top middle, 1992), an audio medium that also has a less popular computer capable cousin known as MD-DATA (upper left). Various MO drives and discs remain in production, but their relatively low capacity and relatively high cost make them niche products.
Iomega and the zip drive
Iomega entered the removable storage business in the 1980s with the Bernoulli Box, which could store 10MB or 20MB of data on large magnetic-disk cartridges. Later revisions of this technology yielded the Zip drive (1994), which could store 100MB of data on an inexpensive 3.5-inch disk. People liked the format because it was inexpensive and capacious, and Zip drives enjoyed strong sales throughout the remaining years of the 1990s. But CD-Rs could store even more data (650MB) and when the price of CD-R discs dropped to cents apiece, Zip drive sales plummeted. Iomega tried to keep up with improved drives of 250MB and then 750MB capacity, but the CD-R had already won. Zip faded into history.
The floptical disk
Insight Peripherals introduced the first "floptical" drive in 1992. It stored 21MB of data on a special 3.5-inch magnetic floppy disk (upper left). Unlike some alternative forms of storage, this promising format was backward-compatible with traditional 3.5-inch floppies. The key to the floptical drive's high capacity was its hybrid "floppy-optical" system, which combined traditional magnetic media with laser-based head tracking for more-precise writes, resulting in more tracks (and more storage) per disk. In the late 1990s, two new backward-compatible floptical formats: the Imation LS-120 SuperDisk (120MB, lower right) and the Sony HiFD (150MB, upper right), debuted and were primed to compete with the Iomega Zip drive. In the end, though, all of them lost out to CD-R.
A removable mess
Following the stunning success of the Zip Drive in the mid- to late 1990s, a raft of competitors and follow-ups emerged, hoping to steal a piece of Zip's pie. Iomega's most prominent competitor was SyQuest, which balkanized and diluted its own market with numerous drives like the SyJet, the SparQ, the EZFlyer, and the EZ135. Another promising (but obscure) competitor was the Castlewood Orb, which stored 2.2GB on a Zip-like disk.
Finally, Iomega itself tried to supplement the Zip with other categories of removable media, from high-capacity removable hard disks (the 1GB and 2GB Jaz Drive) to the miniature 40MB Clik drive. None caught on the way the Zip did.
Not just a flash in the pan
Toshiba invented NAND flash memory in the early 1980s, but the technology didn't gain prominence and plummet in price until the digital camera and PDA boom of the late 1990s. Subsequently it has become available in myriad forms, from large proprietary cards (designed for use in early handheld PCs) to PC Card sizes to CompactFlash, SmartMedia, Secure Digital, Memory Stick, xD Picture Card, and more.
Flash storage is popular because it is completely solid-state with no moving parts. Flash cards require little power to operate, they are rugged, and their storage space has increased exponentially over the years while the media itself remains relatively inexpensive. The first CF cards held 2MB of data; today they can hold 128GB.
Removable storage for your rodent?
This IBM/Hitachi press photo shows not a capybara-size hamster but a tiny Compact Flash-size hard-disk drive called the Microdrive. Introduced in 2003, this miracle of miniaturisation briefly provided high storage capacity and performance for low cost, before ever-more-capacious flash media eclipsed those advantages.
The Apple iPod (2001) and other media players used similar spinning-disk devices, but device makers (and household pets) became frustrated with the Microdrive's inherent fragility, high power requirements, and limited storage capacity. The format is already flirting with obsolescence.
The USB connection
Since 1998 or so, PC users have been living in the USB era. The convenience of USB plug-and-play operation makes every computer user's life easier, and that advantage extends to removable storage as well. Small, portable USB-powered hard drives (lower left) are common today; they hold lots of data and get cheaper every year. Even more popular is today's reigning removable-media champ: the USB thumb drive (introduced in 2000). In coupling flash media's rapidly growing data-storage capability with conveniently small size, the USB key is the format to beat, and it might prove to be the last removable media we'll need.
The hive mind
For the past 15 years, local area networks and the Internet have been replacing removable media for the average computer user. With nearly every computer today now connected to a global network, users rarely need to copy data to external media and move it physically to another computer. Instead, a network of wires and electronic signals takes care of the transfer; A quick email message can carry a file around the world. More significantly, wireless standards such as Bluetooth and Wi-Fi are replacing the need for any physical link at all. Removable media has already become obsolete for many day-to-day computer activities, replaced by bits wandering restlessly through the ether.
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