Floppy disk: Encyclopedia II - Floppy disk - History

Floppy disk - History

Floppy disk - Origins the 8-inch disk

In 1967 IBM gave their San Jose, California storage development center a new task: develop a simple and inexpensive system for loading microcode into their System/370 mainframes. The 370s were the first IBM machines to use semiconductor memory, and whenever the power was turned off the microcode had to be reloaded ('magnetic core' memory, used in the 370s' predecessors, the System/360 line, did not lose its contents when powered down). Normally this task would be left to various tape drives which almost all 370 systems included, but tapes were large and slow. IBM wanted something faster and more purpose-built that could also be used to send out updates to customers for $5.

David Noble, working under the direction of Alan Shugart, tried a number of existing solutions to see if he could develop a new-style tape for the purpose, but eventually gave up and started over. The result was a read-only, 8-inch (20 cm) floppy they called the "memory disk", holding 80 kilobytes. The original versions were simply the disk itself, but dirt became a serious problem and they enclosed it in a plastic envelope lined with fabric that would pick up the dirt. The new device became a standard part of the 370 in 1971.

A Japanese inventor, Yoshiro Nakamatsu (aka Dr. NakaMats), claims he independently came up with the floppy disk principle back in 1950, and so a sales license had to be acquired by IBM when they started manufacturing their floppy disk systems.

In 1973 IBM released a new version of the floppy, this time on the 3740 Data Entry System. The new system used a different recording format that stored up to 250¼ KB on the same disks, and was read-write. These drives became common, and soon were being used to move smaller amounts of data around, almost completely replacing magnetic tapes.

The IBM standard soft-sectored disk format was designed to hold just as much data as one box of punch cards. The disk was divided into 77 tracks of 26 sectors, each holding 128 bytes. Note that 77 * 26 = 2002 sectors, whereas a box of punch cards held 2000 cards.

When the first microcomputers were being developed in the 1970s, the 8-inch floppy found a place on them as one of the few "high speed" 'mass storage' devices that were even remotely affordable to the target market (individuals and small businesses). The first microcomputer operating system, CP/M, originally shipped on 8-inch disks. However the drives were still expensive, typically costing more than the computer they were attached to in early days, so most machines of the era used cassette tape instead.

This began to change with the acceptance of the first standard for the floppy disk, ECMA International-59, authored by Jim O'Reilly of Burroughs, Helmuth Hack of BASF and others. O'Reilly set a record for maneuvering this document through ECMA's approval process, with the standard sub-committee being formed in one meeting of ECMA and approval of a draft standard in the next meeting three months later. This standard later formed the basis for the ANSI standard, too. Standardization brought together a variety of competitors to make media to a single interchangeable standard, and allowed rapid quality and cost improvement.

By this time Alan Shugart had left IBM, moved to Memorex for a brief time, and then again in 1973 to found Shugart Associates. They started working on improvements to the existing 8-inch format, eventually creating a new 800 kB system. However profits were hard to find, and in 1974 he was forced out of his own company.

Burroughs Corporation was meanwhile developing a high-performance dual-sided 8-inch drive at their Glenrothes, Scotland, factory. With a capacity of 1 MB (MiB), this unit exceeded IBM's drive capacity by 4 times, and was able to provide enough space to run all the software and store data on the new Burrough's B80 data entry system, which incidentally had the first VLSI disk controller in the industry. The dual-sided 1MB floppy entered production in 1975, but was plagued by an industry problem, poor media quality. There were few tools available to test media for 'bit-shift' on the inner tracks, which made for high error rates, and the result was a substantial investment by Burroughs in a media tester design that they then gave to media makers as a quality control tool, leading to a vast improvement in yields.

Floppy disk - The 5¼-inch minifloppy

This format is also known as 5.25-inch.

In 1975, Burroughs' plant in Glenrothes developed a prototype 5¼-inch drive, stimulated both by the need to overcome the larger 8-inch floppy's asymmetric expansion properties with changing humidity, and, to reflect the knowledge that IBM's audio recording products division was demonstrating a dictation machine using 5¼-inch disks. In one of the industry's historic gaffes, Burroughs corporate management decided it would be "too inexpensive" to make enough money, and shelved the program.

In 1976 one of Shugart Associates's employees, Jim Adkisson, was approached by An Wang of Wang Laboratories, who felt that the 8-inch format was simply too large for the desktop word processing machines he was developing at the time. After meeting in a bar in Boston, Adkisson asked Wang what size he thought the disks should be, and Wang pointed to a napkin and said "about that size". Adkisson took the napkin back to California, found it to be 5¼-inches (13 cm) wide, and developed a new drive of this size storing 110 KB .

The 5¼-inch drive was considerably less expensive than 8-inch drives from IBM, and soon started appearing on CP/M machines. At one point Shugart was producing 4,000 drives a day. By 1978 there were more than 10 manufacturers producing 5¼-inch floppy drives, in competing physical disk formats: hard-sectored (90 kB) and soft-sectored (110 kB). The 5¼-inch formats quickly displaced the 8-inch from most applications, and the 5¼-inch hard-sectored disk format eventually disappeared. These early drives read only one side of the disk, leading to the popular budget approach of cutting a second write-enable slot and index hole into the carrier envelope and flipping it over (thus, the "flippy disk") to use the other side for additional storage.

Tandon introduced a double-sided drive in 1978, doubling the capacity, and a new "double density" format increased it again, to 360 KB .

For most of the 1970s and 1980s the floppy drive was the primary storage device for microcomputers. Since these micros had no hard drive, the OS was usually from one floppy disk, which was then removed and replaced by another one containing the application. Some machines using two disk drives (or one dual drive) allowed the user to leave the OS disk in place and simply change the application disks as needed. In the early 1980s, 96 track-per-inch drives appeared, increasing the capacity from 360 to 720 KB . These did not see widespread use, as they were not supported by IBM in its PCs. (Another oddball format was used by Digital Equipment Corporation's Rainbow-100, DECmate-II and Pro-350. It held 400 KB on a single side by using 96 tracks-per-inch and cramming 10 sectors per track.) In 1984, along with the IBM PC/AT, the quad density disk appeared, which used 96 tracks per inch combined with a higher density magnetic media to provide 1200 KB (1280 KiB) of storage (normally and misleadingly referred to as 1.2 megabytes). Since the usual (very expensive) hard disk held 10-20 megabytes at the time, this was considered quite spacious.

By the end of the 1980s, the 5¼-inch disks had been superseded by the 3½-inch disks. Though 5¼-inch drives were still available, as were disks, they faded in popularity as the 1990s began. The main community of users was primarily those who still owned '80s legacy machines running MS-DOS that had no 3½-inch drive; the advent of Windows 95 (not even sold in stores in a 5¼-inch version; a coupon had to be obtained and mailed in) and subsequent phaseout of standalone MS-DOS with version 6.22 forced many of them to upgrade their hardware. On most new computers the 5¼-inch drives were optional equipment. By the mid-1990s the drives had virtually disappeared as the 3½-inch disk became the preeminent floppy disk.

Floppy disk - New formats no standard

Throughout the early 1980s the limitations of the 5¼-inch format were starting to become clear. Originally designed to be a smaller and more practical 8-inch, the 5¼-inch system was itself too large, and as the quality of the recording media grew the same amount of data could be placed on a smaller surface. Another problem was that the 5¼-inch disks were simply copies of the 8-inch physical format, which had never really been engineered for ease of use. The thin folded-plastic shell allowed the disk to be easily damaged through bending, and allowed dirt to get onto the disk surface through the opening.

A number of solutions were developed, with drives at 2-inch, 2½-inch, 3-inch and 3½-inch (50, 60, 75 and 90 mm) all being offered by various companies. They all shared a number of advantages over the older format, including a small form factor and a rigid case with a slideable write protect catch. The almost-universal use of the 5¼-inch format made it very difficult for any of these new formats to gain any significant market share.

Standard 3-inch and 3½-inch disks used the same spin speed and basic hardware interface as standard 5¼-inch drives allowing them to be used with existing controllers and formats although new formats later developed that relied on the higher quality hardware in the new drive types (the IBM PC in particular never officially shared a format between the two drive types though it was possible to misidentify the drive to the OS if desired).

Amdek released the AmDisk Micro-Floppy-disk cartridge system in 1982. Originally designed for use with the Apple II Disk II interface card, it has also been connected to other computers with success.

The drive itself was originally designed by Hitachi, Matsushita and Maxell. Only Teac outside this "network" is known to have produced drives. Similarly, only three manufacturers of media (Maxell, Matsushita and Tatung) are known (sometimes also branded Yamaha, Amsoft, Panasonic, Tandy, Godexco, and Dixons), but "no-name" disks with questionable quality have been seen in the wild.

Amstrad incorporated a 3" single-sided drive into their CPC and PCW lines, and this format and the drive mechanism was later "inherited" by the ZX Spectrum +3 computer after Amstrad bought Sinclair. Later models of the PCW featured double-sided, double density drives.

While all 3" media were double-sided in nature, single-sided drive owners were able to flip the disk over to use the other side. The sides were termed "A" and "B" and were completely independent, but single-sided drive units could only access the upper side at one time.

The disk format itself had no more capacity than the more popular (and cheap) 5¼" floppies. Each side held 180 KiB for a total of 360 KiB per disk, and later 720 KiB for the PCW range. Unlike 5¼" or 3½" disks, the 3" disks were designed to be reversible and sported two independent write-protect switches. It was also more reliable thanks to its hard casing (some reviews at the time reported driving over them with no problems).

3" drives were also used on a number of exotic and obscure CP/M systems such as the Tatung Einstein and occasionally on MSX systems in some regions. Other computers to have used this format are the more unknown Gavilan Mobile Computer and Matsushita's National Mybrain 3000. The Yamaha MDR-1 also used 3" drives.

Not a bad format in its own right, but the main problems were the high prices, due to the quite elaborate and complex case mechanisms, and low nominal capacities. However, the tip on the weight was when Sony in 1984 convinced Apple Computer to use the 3½" drives in the Macintosh 128K model, effectively making it a de-facto standard.

It is still possible to source new and used 3" drives from suppliers on the Internet.

Another 3" format was Mitsumi's Quick Disk format. The Quick Disk format is referred to in various size references-- 2.8", 3"x3", and 3"x4". Confusing when trying to categorize the disk but perhaps not when understood that Mitsumi offered this as OEM equipment[1], expecting their VAR customers to customize the packaging for their own particular use. Nintendo packaged the 2.8" magnetic media in a 3"x4" housing, while others packaged the same media in a 3"x3" housing. This explains the different numbering labels, while here we generically call the Mitsumi Quick Disk a 3-inch format.

The Quick Disk's most sucessful use was in Nintendo's Famicom Disk System. The FDS package of Mitumi's Quick Disk used a 3"x4" plastic housing called the "Disk System Card." Most FDS disks did not have cover protection to prevent media contamination, but a later special series of five games did include a protective shutter. [2]

Mitsumi's "3-inch" Quick Disk media was also used in a 3"x3" housing for many Smith Corona word processors[3]. The Smith Corona disks are confusingly labeled "DataDisk 2.8 inch" presumably referring to the size of the media inside the hard plastic case.

The Quick Disk was also used as well in several MIDI keyboards and MIDI samplers of the mid 1980's. A non-inclusive list includes: the Roland S-10[4]MIDI keyboard, Korg SQD8 MIDI sampler[5], Akai's 1985 model MD280 drive for the S-612 MIDI Sampler[6][7][8], Akai's X7000[9] and X3700[10], the Roland S-220[11][12], and a Yamaha MDF1 for their DX7/21/100/TX7, the RX11/21/21L Drum Machine, the QX1, QX21 and QX5 digital musical devices.[13]

As the cost in the 1980's to add 5.25" drives was still quite high, the Mitsumi Quick Disk was competing as a lower cost alernative packaged in several now obscure 8-bit computer systems. Another non-inclusive list of Quick Disk versions: QDM-01[14], in the Casio QD-7 drive[15], in a peripheral for the Sharp MZ-700 & MZ-800 system[16], in the DPQ-280 Quickdisk for the Daewoo/Dynadata MSX1 DPC-200[17][18], in a Dragon machine[19], in the Crescent Quick Disk 128, 128i and 256 peripherals for the ZX Spectrum and ZX Spectrum[20], and in the Triton Quick Disk peripherial also for the ZX Spectrum and ZX Spectrum[21][22].)

The World of Spectrum FAQ reveals that the drives did come in different sizes: 128 to 256K in Cresent's incarnation, and in the Triton system, with a density of 4410 BPI, data transmission rate of 101.6Kb/s, a 2.8" double sided disk type and a capacity of up to 20 sectors per side at 2.5K per sector, up to 100K per disk. Elsewhere it has been reported that a Quick Disk holds 64K of data per side, requiring a manual turn-over to access the second side.

It is significant to note that the Quick Disk utilizes "a continuous linear tracking of the head and thus creates a single spiral track along the disk similar to a record groove."[23] This has led some to compare it more to a "tape-stream" unit than typically what is thought of as a random-access disk drive.[24]

Floppy disk - The 3½-inch microfloppy diskette

Sony also introduced their own small-format 90.0 × 94.0 mm disk, similar to the others but somewhat simpler in construction than the AmDisk. The first computer to use this format was the HP-150 of 1983, and Sony also used them fairly widely on their line of MSX computers. Other than this the format suffered from a similar fate as the other new formats; the 5¼-inch format simply had too much market share.

Things changed dramatically in 1984 when Apple Computer selected the format for their new Macintosh computers, thereby forcing it to become the standard in the United States. (This is yet another example of a "silent" change from metric to imperial units; this product was advertised and became popularly known as the 3½-inch disk, emphasizing the fact that it was smaller than the existing 5¼-inch.) By 1989 the 3½-inch was outselling the 5¼-inch.

The 3½-inch disks had, by way of their rigid case's slide-in-place metal cover, the significant advantage of being much better protected against unintended physical contact with the disk surface when the disk was handled outside the disk drive. When the disk was inserted, a part inside the drive moved the metal cover aside, giving the drive's read/write heads the necessary access to the magnetic recording surfaces. Adding the slide mechanism resulted in a slight departure from the previous square outline. The irregular, rectangular shape had the additional merit that it made it impossible to insert the disk sideways by mistake, as had indeed been possible with earlier formats.

The shutter mechanism was not without its problems however. On old or roughly treated disks it could bend away from the disk. This made it vulnerable to being ripped off completely (which doesn't damage the disk itself but does leave it much more vulnerable to dust) or worse catching inside a drive and possiblly damaging it. If you see a disk with the cover bending away the best option is to rip the cover off (to make sure it doesn't catch in the drive) then immediately copy the data off it. Most modern floppies have a springy plastic cover that does not tend to bend away from the disk.

Like the 5¼-inch, the 3½-inch disk underwent an evolution of its own. They were originally offered in a 360 KB single-sided and 720 KB double-sided double-density format (the same as then-current 5¼-inch disks). A newer "high-density" format, displayed as "HD" on the disks themselves and storing 1440 KB of data, was introduced in the mid-80s (note: these capacities are using the relatively conservative standard PC formats). IBM used it on their PS/2 series introduced in 1987. Apple started using "HD" in 1988, on the Macintosh IIx. It soon became nearly-universal on all PC's. Another advance in the oxide coatings allowed for a new "extended-density" ("ED") format at 2880 KB introduced on the second generation NeXT Computers in 1991, and on IBM PS/2 model 57 also in 1991, but by the time it was available it was already too small to be a useful advance over the HD format and never became widely used. The 3½-inch drives sold more than a decade later still used the same format that was standardized in 1989, in ISO 9529-1,2.

• The formatted capacity of 3½-inch high-density floppies was originally 1440 kibibytes, or 1,474,560 bytes. This is equivalent to 1.41 MiB (1.47 MB decimal). However, their capacity is usually reported as 1.44 MB by diskette manufacturers. The typical data transfer rate can be as much as 24 KB/s, depending on the drive unit. Likewise the ED format is typically referred to as 2.88 MB.

• In some places, especially South Africa, 3½-inch floppy disks have commonly been called stiffies or stiffy disks, because of their "stiff" (rigid) cases, which are contrasted with the flexible "floppy" cases of 5¼-inch floppies. In Finnish, the term is korppu (rusk, crumpet, biscuit) due to its rigidity compared to 5¼-inch lerppu (floppy).

• Even if such a format was hardly officially supported on any system, it is possible to "force" a 3½-inch floppy disk drive to be recognized by the system as a 5¼-inch 360 KB or 1200 KB one (on PCs and compatibles, this can be done by simply changing the CMOS BIOS settings) and thus format and read non-standard disk formats, such as a double sided 360 KB 3½-inch disk. Possible applications include data exchange with obsolete CP/M systems, for example with an Amstrad CPC.

Adapted from the Wikipedia article "History", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki