Floppy disk variants - AbsoluteAstronomy.com

Floppy disk

A floppy disk is a disk storage medium composed of a disk of thin and flexible magnetic storage medium, sealed in a rectangular plastic carrier lined with fabric that removes dust particles...

was a ubiquitous data storage and transfer device from the mid-1970s well into the 2000s. Besides the 3½-inch and 5¼-inch formats used in IBM PC compatible

IBM PC compatible

IBM PC compatible computers are those generally similar to the original IBM PC, XT, and AT. Such computers used to be referred to as PC clones, or IBM clones since they almost exactly duplicated all the significant features of the PC architecture, facilitated by various manufacturers' ability to...

systems, many proprietary floppy disk formats were developed, either using a different disk design or special layout and encoding methods for the data held on the disk.

Commodore 64/128

Commodore started its tradition of special disk formats with the 5¼-inch disk drives accompanying its PET/CBM

Commodore PET

The Commodore PET was a home/personal computer produced from 1977 by Commodore International...

, VIC-20

Commodore VIC-20

The VIC-20 is an 8-bit home computer which was sold by Commodore Business Machines. The VIC-20 was announced in 1980, roughly three years after Commodore's first personal computer, the PET...

and Commodore 64

Commodore 64

The Commodore 64 is an 8-bit home computer introduced by Commodore International in January 1982.Volume production started in the spring of 1982, with machines being released on to the market in August at a price of US$595...

home computers, the same as the 1540

Commodore 1540

The Commodore 1540 was the companion floppy disk drive for the Commodore VIC-20 home computer. It used single-sided 5¼" floppy disks, on which it stored roughly 170 KB of data utilizing Commodore's GCR data encoding scheme.Because of the low price of both the VIC-20 and the 1540, this...

and 1541

Commodore 1541

The Commodore 1541 , made by Commodore International, was the best-known floppy disk drive for the Commodore 64 home computer. The 1541 was a single-sided 170 kilobyte drive for 5¼" disks...

drives used with the later two machines. The standard Commodore Group Code Recording

Group Code Recording

In computer science, group code recording refers to several distinct but related encoding methods for magnetic media. The first, used in 6250 cpi magnetic tape, is an error-correcting code combined with a run length limited encoding scheme...

(GCR) scheme used in 1541 and compatibles employed four different data rates depending upon track position (see zone bit recording
Zone bit recording
Zone Bit Recording is used by disk drives to store more sectors per track on outer tracks than on inner tracks. It is also called Zone Constant Angular Velocity ....

). Tracks 1 to 17 had 21 sectors, 18 to 24 had 19, 25 to 30 had 18, and 31 to 35 had 17, for a disk capacity of 170 kB (170.75 KB). Unique among personal computer architectures, the operating system on the computer itself was unaware of the details of the disk and filesystem; disk operations were handled by Commodore DOS

Commodore DOS

Commodore DOS, aka CBM DOS, was the disk operating system used with Commodore's 8-bit computers. Unlike most other DOS systems before or since—which are booted from disk into the main computer's own RAM at startup, and executed there—CBM DOS was executed internally in the drive: the DOS...

instead, which was implemented with an extra MOS-6502

MOS Technology 6502

The MOS Technology 6502 is an 8-bit microprocessor that was designed by Chuck Peddle and Bill Mensch for MOS Technology in 1975. When it was introduced, it was the least expensive full-featured microprocessor on the market by a considerable margin, costing less than one-sixth the price of...

processor on the disk drive. Many programs such as GEOS

GEOS (8-bit operating system)

GEOS is an operating system from Berkeley Softworks . Originally designed for the Commodore 64 and released in 1986, it provided a graphical user interface for this popular 8-bit computer.GEOS closely resembled early versions of Mac OS and included a graphical word processor and paint program...

bypassed Commodore's DOS completely, and replaced it with "fast loading" programs in the 1541 drive.

Eventually Commodore gave in to disk format standardization, and made its last 5¼-inch drives, the 1570

Commodore 1570

The Commodore 1570 was a 5¼" floppy disk drive for the Commodore 128 home/personal computer. It was a single-sided, 170KB version of the double-sided Commodore 1571, released as a stopgap measure when Commodore International was unable to provide large enough quantities of 1571s due to a shortage...

and 1571

Commodore 1571

The Commodore 1571 was Commodore's high-end 5¼" floppy disk drive. With its double-sided drive mechanism, it had the ability to utilize double-sided, double-density floppy disks natively. This was in contrast to its predecessors, the 1541 and 1570, which could fully utilize such disks only if the...

, compatible with Modified Frequency Modulation

Modified Frequency Modulation

Modified Frequency Modulation, commonly MFM, is a line coding scheme used to encode the actual data-bits on most floppy disk formats, hardware examples include Amiga, most CP/M machines as well as IBM PC compatibles. Early hard disk drives also used this coding.MFM is a modification to the original...

(MFM), to enable the Commodore 128

Commodore 128

The Commodore 128 home/personal computer was the last 8-bit machine commercially released by Commodore Business Machines...

to work with CP/M

CP/M

CP/M was a mass-market operating system created for Intel 8080/85 based microcomputers by Gary Kildall of Digital Research, Inc...

disks from several vendors. Equipped with one of these drives, the C128 was able to access both C64 and CP/M disks, as it needed to, as well as MS-DOS disks (using third-party software), which was a crucial feature for some office work. At least one commercial program, Big Blue Reader by SOGWAP

SOGWAP

SOGWAP Software, its acronymic name standing for Son Of God With All Power, was a company developing and producing Commodore home computer software from 1985 to 1996...

software was available to perform the task.

Commodore also developed a 3½-inch 800 kByte disk format for its 8-bit machines with the 1581

Commodore 1581

The Commodore 1581 is a 3½ inch double sided double density floppy disk drive made by Commodore Business Machines primarily for its C64 and C128 home/personal computers. The drive stores 800 kilobytes using an MFM encoding but format different from both MS-DOS , and the Amiga formats. With...

disk drive, which used only MFM.

The GEOS operating system

GEOS (8-bit operating system)

used a disk format that was largely identical to the Commodore DOS format with a few minor extensions; while generally compatible with standard Commodore disks, certain disk maintenance operations could corrupt the filesystem without proper supervision from the GEOS Kernel.

Atari 8-bit line

The combination of DOS and hardware (810, 1050 and XF551 disk drives) for Atari 8-bit floppy usage allowed sectors numbered from 1 to 720. The DOS' 2.0 disk bitmap provides information on sector allocation, counts from 0 to 719. As a result, sector 720 could not be written to by the DOS. Some companies used a copy protection scheme where "hidden" data was put in sector 720 that could not be copied through the DOS copy option. Another more-common early copy-protected scheme simply did not record important sectors as "used" in the FAT, so the DOS Utility Package (DUP) did not duplicate them. All of these early techniques were thwarted by the first program that simply duplicated all 720 sectors.

Later DOS versions (3.0 and later 2.5) and DOS systems by third parties (i.e. OSS) accepted (and formatted) disks with up to 960 and 1020 sectors, resulting in 127KB storage capacity per disk side on drives equipped with double-density heads (i.e. not the Atari 810) vs. previous 90KB. That unusual 127K format allowed sectors 1-720 to still be read on a single-density 810 disk drive, and was introduced by Atari with the 1050 drive with the introduction of DOS 3.0 in 1983.

A true 180K double-density Atari floppy format used 128 byte sectors for sectors 1-3, then 256 byte sectors for 4-720. The first three sectors typically contain boot code as used by the onboard ROM OS; it is up to the resulting boot program (such as SpartaDOS) to recognize the density of the formatted disk structure. While this 180K format was developed by Atari for their DOS 2.0D and their (canceled) Atari 815 Floppy Drive, that double-density DOS was never widely released and the format was generally used by third-party DOS products. Under the Atari DOS scheme, sector 360 was the FAT sector map, and sectors 361-367 contained the file listing. The Atari-brand DOS versions and compatible used three bytes per sector for housekeeping and to link-list to the next sector.

Third-party DOS systems added features such as double-sided drives, subdirectories, and drive types such as and 8". Well-known 3rd party Atari DOS products included SmartDOS (distributed with the Rana disk drive), TopDos, MyDos and SpartaDOS.

Commodore Amiga

The Commodore Amiga computers used an 880 kByte format (11×512-byte sectors per track, times 80 tracks, times two sides) on a 3½-inch floppy. Because the entire track is written at once, inter-sector gaps could be eliminated, saving space. The Amiga floppy controller was basic but much more flexible than the one on the PC: it was free of arbitrary format restrictions, encoding such as MFM

Modified Frequency Modulation

and GCR

Group Code Recording

could be done in software, and developers were able to create their own proprietary disc formats. Because of this, foreign formats such as the IBM PC-compatible could be handled with ease (by use of CrossDOS

CrossDOS

CrossDOS is file system for AmigaDOS. It was bundled with AmigaOS 2.1 and later, though it did work under Amiga OS 2.04. Its function was to allow working with floppy disks formatted for PCs...

, which was included with later versions of AmigaOS

AmigaOS

AmigaOS is the default native operating system of the Amiga personal computer. It was developed first by Commodore International, and initially introduced in 1985 with the Amiga 1000...

). With the correct filesystem driver

Device driver

In computing, a device driver or software driver is a computer program allowing higher-level computer programs to interact with a hardware device....

, an Amiga could theoretically read any arbitrary format on the 3½-inch floppy, including those recorded at a slightly different rotation rate. On the PC, however, there is no way to read an Amiga disk without special hardware, such as a CatWeasel, or a second floppy drive.

Commodore never upgraded the Amiga chip set

Original Amiga chipset

The Original Chip Set was a chipset used in the earliest Commodore Amiga computers and defined the Amiga's graphics and sound capabilities...

to support high-density floppies, but sold a custom drive (made by Chinon) that spun at half speed (150 RPM

Revolutions per minute

Revolutions per minute is a measure of the frequency of a rotation. It annotates the number of full rotations completed in one minute around a fixed axis...

) when a high-density floppy was inserted, enabling the existing floppy controller to be used. This drive was introduced with the launch of the Amiga 3000

Amiga 3000

The Commodore Amiga 3000, or A3000, was the third major release in the Amiga computer family. Released in June 1990, it features improved processing speed, improved rendering of graphics, and a new revision of the operating system...

, although the later Amiga 1200

Amiga 1200

The Amiga 1200, or A1200 , was Commodore International's third-generation Amiga computer, aimed at the home market...

was only fitted with the standard DD

Double density

Double density, often shortened DD, is a capacity designation on magnetic storage, usually floppy disks. It describes the use of an encoding of information, which can encode on average twice as many bits per time unit compared to single density...

drive. The Amiga HD disks could handle 1760 kByte, but using special software programs it could hold even more data. A company named Kolff Computer Supplies also made an external HD floppy drive (KCS Dual HD Drive) available which could handle HD format diskettes on all Amiga computer systems.

Because of storage reasons, the use of emulators and preserving data, many disks were packed into disk-images. Currently popular formats are .ADF (Amiga Disk File

Amiga Disk File

Amiga Disk File aka ADF is a file format used by Amiga computers and emulators to store images of disks. It has been around almost as long as the Amiga itself, although it was not initially called by any particular name. Before it was known as ADF, it was used in commercial game production, backup...

), .DMS (DiskMasher

Disk Masher System

The Disk Masher System was an often used method on Amiga, to create a compressed image of a disk . The disk is read block-by-block, and thus its data structure is maintained...

) and .IPF (Interchangeable Preservation Format) files. The DiskMasher format is copyright-protected and has problems storing particular sequences of bits due to bugs in the compression algorithm, but was widely used in the pirate and demo scenes. ADF

Amiga Disk File

has been around for almost as long as the Amiga itself though it was not initially called by that name. Only with the advent of the Internet and Amiga emulators has it become a popular way of distributing disk images. The proprietary IPF files were created to allow preservation of commercial games which have copy protection, which is something that ADF and DMS unfortunately cannot do.

Acorn Electron, BBC Micro, and Acorn Archimedes

The British company Acorn Computers

Acorn Computers

Acorn Computers Ltd. was a British computer company established in Cambridge, England, in 1978. The company produced a number of computers which were especially popular in the UK. These included the Acorn Electron, the BBC Micro, and the Acorn Archimedes...

used non-standard disk formats in their 8-bit BBC Micro

BBC Micro

The BBC Microcomputer System, or BBC Micro, was a series of microcomputers and associated peripherals designed and built by Acorn Computers for the BBC Computer Literacy Project, operated by the British Broadcasting Corporation...

and Acorn Electron

Acorn Electron

The Acorn Electron is a budget version of the BBC Micro educational/home computer made by Acorn Computers Ltd. It has 32 kilobytes of RAM, and its ROM includes BBC BASIC along with its operating system....

, and their successor the 32-bit Acorn Archimedes

Acorn Archimedes

The Acorn Archimedes was Acorn Computers Ltd's first general purpose home computer to be based on their own ARM architecture.Using a RISC design with a 32-bit CPU, at its launch in June 1987, the Archimedes was stated as running at 4 MIPS, with a claim of 18 MIPS during tests.The name is commonly...

. Acorn however, used standard disk controllers: initially FM, though they quickly transitioned to MFM. The original disk implementation for the BBC Micro stored 100 KB (40 track) or 200 KB (80 track) per side on 5¼-inch disks in a custom format using the Disc Filing System

Disc Filing System

The Disc Filing System is a computer file system developed by Acorn Computers Ltd, and introduced in 1982 for the Acorn BBC Microcomputer. It was shipped as a ROM to be inserted onto the BBC Micro's motherboard. It has an extremely limited design, and uses a flat directory structure...

(DFS).

Due to the incompatibility between 40 and 80 track drives, much software was distributed on combined 40/80 track discs. These worked by writing the same data in pairs of consecutive tracks in 80 track format, and including a small loader program on track 1 (which is in the same physical position in either format). The loader program detected which type of drive was in use, and loaded the main software program straight from disc bypassing the DFS, double-stepping for 80 track drives and single-stepping for 40 track. This effectively achieved downgraded capacity to 100 KB from either disk format, but enabled distributed software to be effectively compatible with either drive.

For their Electron floppy disk add-on added, Acorn picked 3½-inch disks and developed the Advanced Disc Filing System

Advanced Disc Filing System

The Advanced Disc Filing System is a computing file system particular to the Acorn computer range and RISC OS based successors. Initially based on the rare Acorn Winchester Filing System, it was renamed to the Advanced Disc Filing System when support for floppy discs was added and on later 32 bit...

(ADFS). It used double-density recording and added the ability to treat both sides of the disk as a single drive. This offered three formats:

S (small): 160 KB, 40-track single-sided;
M (medium): 320 KB, 80-track single-sided;
L (large): 640 KB, 80-track double-sided.

ADFS provided hierarchical directory structure, rather than the flat model of DFS. ADFS also stored some metadata about each file, notably a load address, an execution address, owner and public privileges, and a "lock" bit. Even on the eight-bit machines, load addresses were stored in 32-bit format, since those machines supported 16 and 32-bit coprocessor

Coprocessor

A coprocessor is a computer processor used to supplement the functions of the primary processor . Operations performed by the coprocessor may be floating point arithmetic, graphics, signal processing, string processing, or encryption. By offloading processor-intensive tasks from the main processor,...

s.

The ADFS format was later adopted into the BBC line upon release of the BBC Master

BBC Master

The BBC Master was a home computer released by Acorn Computers in early 1986. It was designed and built for the British Broadcasting Corporation and was the successor to the BBC Micro Model B. The Master 128 remained in production until 1993....

. The BBC Master Compact marked the move to 3½-inch disks, using the same ADFS formats.

The Acorn Archimedes added D format, which increased the number of objects per directory from 44 to 77 and increased the storage space to 800 KB. The extra space was obtained by using 1024 byte sectors instead of the usual 512 bytes, thus reducing the space needed for inter-sector gaps. As a further enhancement, successive tracks were offset by a sector, giving time for the head to advance to the next track without missing the first sector, thus increasing bulk throughput. The Archimedes used special values in the ADFS load/execute address metadata to store a 12-bit filetype field and a 40-bit timestamp.

RISC OS

RISC OS

RISC OS is a computer operating system originally developed by Acorn Computers Ltd in Cambridge, England for their range of desktop computers, based on their own ARM architecture. First released in 1987, under the name Arthur, the subsequent iteration was renamed as in 1988...

2 introduced E format, which retained the same physical layout as D format, but supported file fragmentation and auto-compaction. Post-1991 machines including the A5000 and Risc PC

Risc PC

The RiscPC was Acorn Computers's next generation RISC OS/Acorn RISC Machine computer, launched on 15 April 1994, which superseded the Acorn Archimedes. The Acorn PC card and software allows PC compatible software to be run....

added support for high-density disks with F format, storing 1600 KB. However, the PC combo IO

Super I/O

Super I/O is a class of I/O controller integrated circuits that began to be used on personal computer motherboards in the late 1980s, originally as add-in cards, later embedded on the motherboards. A super I/O chip combines interfaces for a variety of low-bandwidth devices...

chips used were unable to format disks with sector skew, losing some performance. ADFS and the PC controllers also support extended-density disks as G format, storing 3200 KB, but ED drives were never fitted to production machines.

With RISC OS 3, the Archimedes could also read and write disk formats from other machines, for example the Atari ST and the IBM PC. With third party software it could even read the BBC Micro's original single density 5¼-inch DFS disks. The Amiga's disks could not be read as they used unusual sector gap markers.

The Acorn filesystem design was interesting because all ADFS-based storage devices connected to a module called FileCore which provided almost all the features required to implement an ADFS-compatible filesystem. Because of this modular design, it was easy in RISC OS 3 to add support for so-called image filing systems. These were used to implement completely transparent support for IBM PC format floppy disks, including the slightly different Atari ST

Atari ST

The Atari ST is a home/personal computer that was released by Atari Corporation in 1985 and commercially available from that summer into the early 1990s. The "ST" officially stands for "Sixteen/Thirty-two", which referred to the Motorola 68000's 16-bit external bus and 32-bit internals...

format. Computer Concepts

Xara

Xara is a UK-based software company founded in 1981. It has developed software for a variety of computer platforms, in chronological order: The Acorn Atom, BBC Micro, Z88, Atari ST, Acorn Archimedes, Microsoft Windows and Linux. It was originally called Computer Concepts, Ltd.; the company name...

released a package that implemented an image filing system to allow access to high density Macintosh

Macintosh

The Macintosh , or Mac, is a series of several lines of personal computers designed, developed, and marketed by Apple Inc. The first Macintosh was introduced by Apple's then-chairman Steve Jobs on January 24, 1984; it was the first commercially successful personal computer to feature a mouse and a...

format disks.

Amstrad CPC

The 3-inch disk, widely used on Amstrad CPC

Amstrad CPC

The Amstrad CPC is a series of 8-bit home computers produced by Amstrad between 1984 and 1990. It was designed to compete in the mid-1980s home computer market dominated by the Commodore 64 and the Sinclair ZX Spectrum, where it successfully established itself primarily in the United Kingdom,...

machines, bears much similarity to the 3½-inch type, with some unique and somewhat curious features. One example is the rectangular-shaped plastic casing, almost taller than a 3½-inch disk, but narrower, and more than twice as thick, almost the size of a standard compact audio cassette. This made the disk look more like a greatly oversized present day memory card

Memory card

A memory card or flash card is an electronic flash memory data storage device used for storing digital information. They are commonly used in many electronic devices, including digital cameras, mobile phones, laptop computers, MP3 players, and video game consoles...

or a standard PC card

PC card

In computing, PC Card is the form factor of a peripheral interface designed for laptop computers. The PC Card standard was defined and developed by the Personal Computer Memory Card International Association which itself was created by a number of computer industry companies in the United States...

notebook expansion card rather than a floppy disk. Despite the size, the actual 3-inch magnetic-coated disk occupied less than 50% of the space inside the casing, the rest being used by the complex protection and sealing mechanisms implemented on the disks. Such mechanisms were largely responsible for the thickness, length and high costs of the 3-inch disks. On the Amstrad machines the disks were typically flipped over to use both sides, as opposed to being truly double-sided. Double-sided mechanisms were available but rare.

IBM DemiDiskettes

In the early 80s, IBM Rochester developed a 4-inch floppy diskette, the DemiDiskette. This program was driven by aggressive cost goals, but missed the pulse of the industry. The prospective users, both inside and outside IBM, preferred standardization to what by release time were small cost reductions, and were unwilling to retool packaging, interface chips and applications for a proprietary design. The product never appeared in the light of day, and IBM wrote off several hundred million dollars of development and manufacturing facility. IBM obtained patent number on the media and the drive for the DemiDiskette. At trade shows, the drive and media were labeled "Brown" and "Tabor".

Auto-loaders

IBM developed, and several companies copied, an autoloader mechanism that could load a stack of floppies one at a time into a drive unit. These were very bulky systems, and suffered from media hangups and chew-ups more than standard drives, but they were a partial answer to replication and large removable storage needs. The smaller 5¼- and 3½-inch floppy made this a much easier technology to perfect.

Floppy mass storage

A number of companies, including IBM and Burroughs, experimented with using large numbers of unenclosed disks to create massive amounts of storage. The Burroughs system used a stack of 256 12-inch disks, spinning at a high speed. The disk to be accessed was selected by using air jets to part the stack, and then a pair of heads flew over the surface as in any standard hard disk drive. This approach in some ways anticipated the Bernoulli disk technology implemented in the Iomega

Iomega

Iomega is an American producer of consumer external, portable and networking storage hardware. Established in the 1980s, Iomega has sold more than 410 million digital storage drives and disks. On April 8, 2008, EMC Corporation announced its plans to acquire Iomega for a consideration of US $213M...

Bernoulli Box

The Bernoulli Box was a high-capacity removable disk storage system that was Iomega's first widely-known product...

, but head crash

Head crash

A head crash is a hard-disk failure that occurs when a read–write head of a hard disk drive comes in contact with its rotating platter, resulting in permanent and usually irreparable damage to the magnetic media on the platter surface....

es or air failures were spectacularly messy. The program did not reach production.

2-inch floppy disks

At least two mutually-incompatible floppy disks measuring two inches appeared in the 1980s.

One of these, officially referred to as a Video Floppy (or VF for short) was used to store video information for still video camera

Still video camera

A still video camera is a type of electronic camera that takes still images and stores them as single frames of video. They peaked in popularity in the late 1980s and can be seen as the predecessor to the digital camera...

s such as the original Sony

Sony

, commonly referred to as Sony, is a Japanese multinational conglomerate corporation headquartered in Minato, Tokyo, Japan and the world's fifth largest media conglomerate measured by revenues....

Mavica (not to be confused with later Digital Mavica models) and the Ion and Xapshot cameras from Canon. VF was not a digital data format; each track on the disk stored one video field in the analog interlaced composite video

Composite video

Composite video is the format of an analog television signal before it is combined with a sound signal and modulated onto an RF carrier. In contrast to component video it contains all required video information, including colors in a single line-level signal...

format in either the North American NTSC

NTSC

NTSC, named for the National Television System Committee, is the analog television system that is used in most of North America, most of South America , Burma, South Korea, Taiwan, Japan, the Philippines, and some Pacific island nations and territories .Most countries using the NTSC standard, as...

or European PAL

PAL

PAL, short for Phase Alternating Line, is an analogue television colour encoding system used in broadcast television systems in many countries. Other common analogue television systems are NTSC and SECAM. This page primarily discusses the PAL colour encoding system...

standard. This yielded a capacity of 25 images per disk in frame mode and 50 in field mode.
Another one, the LT-1, was digitally formatted - 720 kB, 245TPI, 80 tracks/side, double-sided, double-density. They were used exclusively in the Zenith Minisport

Zenith Minisport

The Zenith MiniSport, introduced in 1989 by Zenith Electronics Corporation, was a small laptop based on a 80C88 CMOS CPU running at 4.77 MHz or 8 MHz, software selectable....

laptop computer circa 1989. Although the media exhibited nearly identical performance to the 3½-inch disks of the time, they were not successful. This was due in part to the scarcity of other devices using this drive making it impractical for software transfer, and high media cost which was much more than 3½-inch and 5¼-inch disks of the time.

Standard floppy replacements

Through the early 1990s a number of attempts were made by various companies to introduce newer floppy-like formats based on the now-universal 3½-inch physical format. Most of these systems provided the ability to read and write standard DD and HD disks, while at the same time introducing a much higher-capacity format as well. None of these ever reached the point where it could be assumed that every current PC would have one, and they have now largely been replaced by CD

CD-R

A CD-R is a variation of the Compact Disc invented by Philips and Sony. CD-R is a Write Once Read Many optical medium, though the whole disk does not have to be entirely written in the same session....

and DVD

DVD

A DVD is an optical disc storage media format, invented and developed by Philips, Sony, Toshiba, and Panasonic in 1995. DVDs offer higher storage capacity than Compact Discs while having the same dimensions....

burners and USB flash drive

USB flash drive

A flash drive is a data storage device that consists of flash memory with an integrated Universal Serial Bus interface. flash drives are typically removable and rewritable, and physically much smaller than a floppy disk. Most weigh less than 30 g...

s. Nevertheless, the 5¼ and 3½-inch sizes remain to this day as the standard for drive bay

Drive bay

A drive bay is a standard-sized area for adding hardware to a computer. Most drive bays are fixed to the inside of a case, but some can be removed....

s in computer case

Computer case

A computer case is the enclosure that contains most of the components of a computer...

s, the former used for CD and DVD (including Blu-ray

Blu-ray Disc

Blu-ray Disc is an optical disc storage medium designed to supersede the DVD format. The plastic disc is 120 mm in diameter and 1.2 mm thick, the same size as DVDs and CDs. Blu-ray Discs contain 25 GB per layer, with dual layer discs being the norm for feature-length video discs...

), and the latter for hard disk drives.

The main technological change for the higher-capacity formats was the addition of tracking information on the disk surface to allow the read/write heads to be positioned more accurately. Normal disks have no such information, so the drives use the tracks themselves with a feedback loop in order to center themselves. The newer systems generally used marks burned onto the surface of the disk to find the tracks, allowing the track width to be greatly reduced.

Flextra

As early as 1988, Brier Technology introduced the Flextra BR 3020, which boasted 21.4 MB (a value used for marketing: its true size was 21,040 KB, 2 sides × 526 cyl × 40 tracks × 512 bytes or 25 MB unformatted). Later the same year it introduced the BR3225, which doubled the capacity. This model could also read standard 3½-inch disks.

It used 3½-inch standard disks which had servo information embedded on them for use with the Twin Tier Tracking technology.

Original Floptical

In 1991, Insite Peripherals introduced the "Floptical

Floptical

Floptical refers to a type of disk drive that combines magnetic and optical technologies to store large amounts of data on media similar to 3½-inch floppy disks. The name is a portmanteau of the words 'floppy' and 'optical'...

", which used an infra-red LED

LEd

LEd is a TeX/LaTeX editing software working under Microsoft Windows. It is a freeware product....

to position the heads over marks in the disk surface. The original drive stored 21 MB, while also reading and writing standard DD and HD floppies. In order to improve data transfer speeds and make the high-capacity drive usefully quick as well, the drives were attached to the system using a SCSI

SCSI

Small Computer System Interface is a set of standards for physically connecting and transferring data between computers and peripheral devices. The SCSI standards define commands, protocols, and electrical and optical interfaces. SCSI is most commonly used for hard disks and tape drives, but it...

connector instead of the normal floppy controller. This made them appear to the operating system

Operating system

An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...

as a hard drive instead of a floppy, meaning that most PCs were unable to boot from them. This again adversely affected pickup rates.

Insite licensed their technology to a number of companies, who introduced compatible devices as well as even larger-capacity formats. The most popular of these, by far, was the LS-120, mentioned below.

Zip drive

In 1994, Iomega

Iomega

introduced the Zip drive

Zip drive

The Zip drive is a medium-capacity removable disk storage system that was introduced by Iomega in late 1994. Originally, Zip disks launched with capacities of 100 MB, but later versions increased this to first 250 MB and then 750 MB....

. Although it did not conform to the 3½-inch form factor and hence was not compatible with standard 1.44 MB drives, it still became the most popular of the "super floppies". It boasted 100 MB, later 250 MB, and then 750 MB of storage. Though Zip drives gained in popularity for several years they never reached the same market penetration as standard floppy drives, since only some new computers were sold with the drives. Eventually the falling prices of CD-R

CD-R

and CD-RW

CD-RW

A CD-RW is a rewritable optical disc. It was introduced in 1997, and was known as "CD-Writable" during development. It was preceded by the CD-MO, which was never commercially released....

media and USB flash drive

USB flash drive

s, along with notorious hardware failures (the so-called "click of death

Click of death

Click of death is a term that became common in the late 1990s referring to the clicking sound in disk storage systems that signals the disk drive has failed, often catastrophically.- Origin of the term :...

"), reduced the popularity of the Zip drive.

A major reason for the failure of the Zip Drives is also attributed to the higher pricing they carried (partly because of royalties

Royalties

Royalties are usage-based payments made by one party to another for the right to ongoing use of an asset, sometimes an intellectual property...

that 3rd-party manufacturers of drives and disks had to pay). Zip drive media was primarily popular for the excellent storage density and drive speed they carried, but were always overshadowed by the price.

LS-120

Announced in 1995, the "SuperDisk

SuperDisk

The SuperDisk, sometimes marketed as LS-120 and a later variant LS-240, is a high-speed, high-capacity alternative to the 90 mm , 1.44 MB floppy disk. The Superdisk hardware was introduced by 3M's storage products group circa 1997...

" marketed as the LS-120 drive, often seen with the brand names Matsushita (Panasonic) and Imation

Imation

Imation is a US based multi-national technology corporation that designs, manufactures and sells recordable data storage media, consumer electronics products and accessories.The company is a 1996 spin off of 3M and is headquartered in Oakdale, Minnesota...

, had an initial capacity of 120 MB (120.375 MB

Megabyte

The megabyte is a multiple of the unit byte for digital information storage or transmission with two different values depending on context: bytes generally for computer memory; and one million bytes generally for computer storage. The IEEE Standards Board has decided that "Mega will mean 1 000...

) using even higher density "LS-120" disks.

It was upgraded (as the "LS-240") to 240 MB (240.75 MB). Not only could the drive read and write 1440 kB disks, but the last versions of the drives could write 32 MB onto a normal 1440 kB disk (see note below). Unfortunately, popular opinion held the Super Disk disks to be quite unreliable, though no more so than the Zip drive

Zip drive

s and SyQuest Technology

SyQuest Technology

SyQuest Technology, Inc., now known as SYQT, Inc., was an early entrant into the removable hard disk market for personal computers. The company was started in 1982 by Syed Iftikar; it was named partially after himself because of a company meeting wherein it was decided that "SyQuest" ought to be a...

offerings of the same period and there were also many reported problems moving standard floppies between LS-120 drives and normal floppy drives. This belief, true or otherwise, crippled adoption. The BIOS

BIOS

In IBM PC compatible computers, the basic input/output system , also known as the System BIOS or ROM BIOS , is a de facto standard defining a firmware interface....

of many motherboards even to this day supports LS-120 drives as boot options.

LS-120 compatible drives were available as options on many computers, including desktop and notebook computers from Compaq Computer Corporation

Compaq

Compaq Computer Corporation is a personal computer company founded in 1982. Once the largest supplier of personal computing systems in the world, Compaq existed as an independent corporation until 2002, when it was acquired for US$25 billion by Hewlett-Packard....

. In the case of the Compaq notebooks, the LS-120 drive replaced the standard floppy drive in a multibay configuration.

Sony HiFD

Sony introduced its own floptical-like system in 1997 as the "150 MB Sony HiFD

Sony HiFD

The Sony HiFD was an attempt by Sony to replace their own aging 3.5 inch floppy disk, which had proven successful in the late-1980s war to replace the 5.25 inch floppy disk....

" which could hold 150 megabytes (157.3 actual megabytes) of data. Although by this time the LS-120 had already garnered some market penetration, industry observers nevertheless confidently predicted the HiFD would be the real standard-floppy-killer and finally replace standard floppies in all machines.

After only a short time on the market the product was pulled, as it was discovered there were a number of performance and reliability problems that made the system essentially unusable. Sony then re-engineered the device for a quick re-release, but then extended the delay well into 1998 instead, and increased the capacity to "200 MB" (approximately 210 megabytes) while they were at it. By this point the market was already saturated by the Zip disk, so it never gained much market share.

Caleb Technology’s UHD144

The UHD144

Caleb UHD144

The Caleb Technology UHD144 was a floptical-based 144 MB floppy disk system introduced in early 1998, marketed as the it drive. Like other floptical-like systems, the UHD144 could read and write standard 720KB and 1.44MB 3½-inch disks as well...

drive surfaced early in 1998 as the it drive, and provided 144 MB of storage while also being compatible with the standard 1.44 MB floppies. The drive was slower than its competitors but the media were cheaper, running about 8 US$ at introduction and 5 US$ soon after.

External links

Programming Floppy Disk Controllers
HowStuffWorks: How Floppy Disk Drives Work
Computer Hope: Information about computer floppy drives
NCITS (mention of ANSI X3.162 and X3.171 floppy standards)
Floppy Drive Tech Info
Floppy disk drives and media technical information
War of the Microdisks Popular Science, Dec. 1983

The source of this article is wikipedia, the free encyclopedia. The text of this article is licensed under the GFDL.

Commodore 64/128

Atari 8-bit line

Commodore Amiga

Acorn Electron, BBC Micro, and Acorn Archimedes

Amstrad CPC

IBM DemiDiskettes

Auto-loaders

Floppy mass storage

2-inch floppy disks

Standard floppy replacements

Flextra

Original Floptical

Zip drive

LS-120

Sony HiFD

Caleb Technology’s UHD144

See also

External links