3.4. COMPUTER MEMORY

FLEXIBLE MAGNETIC DISKS

Diskette- portable magnetic storage medium used for multiple recording and storage of relatively small data. This type of media was especially common in the 1970s and late 1990s. The abbreviation is sometimes used instead of the term "floppy disk" GMD- "floppy disk" (respectively, the device for working with floppy disks is called NGMD- "floppy disk drive").

Typically, a floppy disk is a flexible plastic plate covered with a ferromagnetic layer, hence the English name "floppy disk" (" floppy disk"). This plate is housed in a plastic case that protects the magnetic layer from physical damage. The shell can be flexible or rigid. Floppy disks are written and read using a special device - a floppy disk drive (floppy drive).

Floppy disks usually have a write protection feature, through which you can provide read-only access to data.

Floppy disks (8 ″; 5, 25 ″ ; 3.5 ″ respectively)

History

· 1971 - The first 200 mm (8 ″) floppy disk with a suitable floppy disk drive was introduced by IBM. Usually the invention itself is attributed to Alan Sugart, who worked at IBM in the late 1960s.

· 1973 - Alan Shugert founds his own firm, Shugart Associates.

· 1976 - Alan Schugert develops the 5.25 ″ floppy disk.

· 1981 - Sony introduces a 3.5 ″ (90 mm) floppy disk to the market. In the first version, the volume is 720 kilobytes (9 sectors). Late version has a volume of 1440 kilobytes or 1.40 megabytes (18 sectors). It is this type of floppy disk that becomes the standard (after IBM uses it in its IBM PC).

Later, the so-called ED floppy disks appeared (from the English. Extended Density- "extended density"), which had a volume of 2880 kilobytes (36 sectors), which did not become widespread.

Formats

Chronology of the emergence of floppy disk formats
Format	Year of origin	Volume in kilobytes
8 ″ double density
5.25 "double density
5.25 ″ Quad Density
5.25 "high density
3 ″ double density
3.5 ″ double density
3.5 "high density
3.5 ″ expanded density

It should be noted that the actual capacity of the floppy disks depended on how they were formatted. Since, apart from the earliest models, virtually all floppy disks did not contain hard-formed tracks, the path for experiments in the field of more efficient use of a floppy disk was open for system programmers. The result was the emergence of many incompatible floppy disk formats, even under the same operating systems. For example, for RT-11 and its versions adapted in the USSR, the number of incompatible diskette formats in circulation exceeded ten. (The most famous are MX, MY used in DCK).

Added to the confusion was the fact that Apple used floppy drives in its Macintosh computers that use a different encoding principle for magnetic recording than the IBM PC. As a result, despite using identical floppy disks, transferring information between platforms on floppy disks was not possible until Apple introduced high-density SuperDrives that worked in both modes.

The "standard" formats of IBM PC floppy disks differed in disk size, the number of sectors per track, the number of sides used (SS stands for single-sided floppy, DS stands for double-sided), and the type (recording density) of the drive. The drive type was marked as SD - single density, DD - double density, QD - quadruple density (used in clones such as Robotron-1910 - 5.25 "floppy disk 720 K, Amstrad PC, PK Neuron - 5.25" floppy disk 640 K , HD - high density (differed from QD by the increased number of sectors), ED - extended density.

Working floppy densities and floppy capacities in kilobytes
Density	Inch

8-inch drives have long been included in the BIOS and were supported by MS-DOS, but there is no exact information about whether they were supplied to consumers (perhaps they were supplied to enterprises and organizations and were not sold to individuals).

In addition to the above format variations, there were a number of improvements and deviations from the standard floppy disk format. The most famous - 320/360 KB floppy disks Iskra-1030 / Iskra-1031 - actually were SS / QD floppy disks, but their boot sector was marked as DS / DD. As a result, the standard IBM PC drive could not read them without using special drivers (800.com), and the Iskra-1030 / Iskra-1031 drive, respectively, could not read the standard DS / DD diskettes from the IBM PC.

Special drivers-extenders BIOS 800, pu_1700 and a number of others allowed formatting floppy disks with an arbitrary number of tracks and sectors. Since floppy drives usually supported from one to 4 additional tracks, and also allowed, depending on design features, format by 1-4 sectors per track more than the standard, these drivers ensured the appearance of such non-standard formats as 800 Kb (80 tracks, 10 sectors) 840 Kb (84 tracks, 10 sectors), etc. Maximum capacity, consistently achieved by this method by 3.5″ HD drives was 1700 KB.

This technique was later used in Windows 98, as well as Microsoft's DMF floppy disk format, which expanded the floppy disk capacity to 1.68 MB by formatting the 21-sector floppy disks in the IBM-like XDF format. XDF was used in OS / 2 distributions, and DMF was used in distributions of various software products from Microsoft.

Finally, a fairly common modification of the 3.5 ″ floppy format is to format them at 1.2 MB (with a reduced number of sectors). This feature can usually be enabled in the BIOS. modern computers... This use of 3.5 ″ is typical for Japan and South Africa R. As a side effect, the activation of this BIOS settings usually allows you to read floppy disks formatted using 800 type drivers.

Additional (non-standard) tracks and sectors sometimes contained copy protection data of proprietary floppy disks. Standard programs, such as diskcopy did not transfer these sectors when copying.

The unformatted capacity of a 3.5 ″ floppy disk, determined by recording density and media area, is 2 MB.

The height of a 5.25 "floppy disk drive is 1 U. All CD drives, including Blu-ray, are the same width and height as a 5.25" drive (this does not apply to notebook drives).

The width of a 5.25 ″ drive is almost equal to three times its height. This was sometimes used by the manufacturers of computer cases, where three devices placed in a square "basket" could be reoriented with it from horizontal to vertical arrangement.

Disappearing

One of the main problems with floppy disks was their fragility. The most vulnerable element of the floppy disk design was a tin or plastic casing that covered the floppy disk itself: its edges could bend, which led to the floppy disk getting stuck in the floppy drive, the spring that returned the casing to its original position could be displaced, as a result, the floppy casing was separated from the case and never returned to starting position. The plastic case of the floppy disk itself did not provide sufficient protection for the floppy disk from mechanical damage (for example, when a floppy disk fell on the floor), which rendered the magnetic medium out of order. Dust may have entered the crevices between the diskette case and the casing. And the floppy disk itself could be relatively easily demagnetized from the influence of magnetized metal surfaces, natural magnets, electromagnetic fields near high-frequency devices, which made the storage of information on floppy disks extremely unreliable.

The massive displacement of floppy disks from everyday life began with the advent of rewritable CDs, and especially flash-based media, which have a much lower unit cost, orders of magnitude greater capacity, higher actual number of rewriting cycles and durability, and higher data exchange rate.

An intermediate option between them and traditional floppy disks are magneto-optical media, Iomega Zip, Iomega Jaz and others. These removable media are sometimes also called floppy disks.

However, even in 2009, a floppy disk (usually 3.5 ") and an appropriate disk drive are required (if it is impossible to do this via the Internet directly from operating system) to "flash" the BIOS flash of many motherboards such as Gigabyte. They are also used to work with small files (usually with text files), to transfer these files from one computer to another. So we can say with full confidence that floppy disks will be used for several more years, at least until the moment when the price of the cheapest flash drives will not be comparable to the prices for floppy disks (now their difference is ~ 10 times, but it is steadily decreasing) ...

"Distant 1967. Specialists of the IBM laboratory from San Jose, engaged in the development of storage media, are trying to create an inexpensive device capable of storing and transferring firmware for processors, mainframes and control modules. The delivery should not cause any difficulties, and the reliability should not be in doubt. "

Now it's 2005 - 38 years have passed since the first prototype of the floppy disk appeared, but FDD continues to live! What is the secret of such survivability of this "relic" of the past, the same as a dot matrix printer or a COM port? It seems to me, in the price / reliability / quality ratio. It is now difficult for us to understand what kind of revolution a common floppy disk caused in due time. It's a pity! In an instant, tons of punched cards and kilometers of magnetic tape were no longer needed. One plastic envelope and no problems or mistakes! What will be discussed today should reveal to the reader in full the genius of such a nondescript, at first glance, invention, like an ordinary floppy disk.

It is believed that floppy drive disks were invented in 1971 to solve a problem IBM faced with the System 370 computer. The problem was that the programs stored in its semiconductor memory were erased whenever the computer was turned off. "To reboot the machine, you had to write the control program back into memory," recalled Al Shugart, then IBM's direct storage manager. Subsequently, the founder of Shugart Associates and the manufacturer of storage devices - Seagate Technology.

Although Shugart is often called the father of the floppy disk, he himself considers David Noble to be its real creator. Noble, was a senior engineer at the San Jose laboratory and stood firm on his shoulders as Shugart's only subordinate. First of all, Noble tried out the technologies that existed then. But I soon realized that we had to look for fundamentally new ways. It was then that the first floppy disk was proposed. Within a year, Noble (whose group had already grown significantly) completed work on a device that IBM called "memory disk". It was actually a floppy disk. It was an 8-inch plastic disc coated with iron oxide for read-only access. This disk weighed about 2 ounces and had a capacity of 80 KB. The turning point in the creation of the floppy disk was the invention of the protective case. "We got our disk working, but we couldn't offer a good protective shell for it," Shugart recalled. - "Any speck of dust completely destroyed the data. The percentage of errors was very high." And so the developers came up with the idea to place the device in a case made of non-woven material, which would ensure constant wiping of the surface of the floppy disk during its rotation. Thus, the surface was always clean. "This idea ultimately decided the whole thing," says Shugart.

After extensive testing, the diskette was integrated into the System 370; this happened in 1971. It was also used to load firmware into the IBM Merlin 3330 disk package controller.

Yet the design of the floppy, introduced in 1971, has not become the industry standard, said Jim Porter, now president of Disk / Trend think tank. At the time in question, Porter worked for MEMOREX, an independent floppy disk company. In 1973 IBM introduced new version floppy disks, this time for the 3704 Data Entry System. "The recording format was completely different, and the disk was spinning in the opposite direction," Porter explained. It provided read / write capabilities and could store up to 256 KB of data. Users now have the ability to enter data from floppy disks, and not from punched cards. The fundamental difference between the invention and all the previous ones was in the floppy disk drive (floppy disk, or just a floppy disk), where there were two motors: one provided a stable rotation speed of the floppy disk inserted into the drive, and the second moved the read-write head. The rotation speed of the first engine depended on the type of floppy disk and ranged from 300 to 360 rpm. The motor for moving the heads in these drives has always been a stepper motor. With its help, the heads were moved along the radius from the edge of the disk to its center in discrete intervals. Unlike the drive of the hard drive, the heads in this device did not "hover" above the surface, but touched it.

IBM officials said the new device could hold the same amount of information as 3,000 punched cards. The release of the new floppy disk has become a kind of a starting gun for the manufacturers of these devices. Even now, some companies use 8-inch floppy disks !!! Mainly when working with computerized machines. But in 1976, about the same time as the first personal computers, a 5.25-inch floppy disk was developed.

In the words of Porter (Wang Laboratories) - who worked on a desktop computer that could act as a word processor: "The eight-inch floppy disk was obviously too big for him." The company, in collaboration with Shugart Associates, has begun work on a smaller device. "" We had a very heated discussion about the size of the floppy - we sat all night in one of the bars in Boston. The answer was prompted by chance - someone noticed a napkin placed under a glass with a cocktail, its size was just 5.25 inches, - Porter recalled. “We kidnapped her, brought her to Boston and told our engineers:" Since such a trifle is in demand, let our floppy disk be the same size. " The improvement of floppy disks did not stop at the size of the napkin; as a consequence, the now so popular three-inch floppy disk, developed by Sony Corporation more than 30 years ago, appeared. This drive has lived a rich life and still lives today, although it should be noted that most companies have already abandoned their own production of 3-inch floppy disks. One of the first firms to close their floppy disk factories was in 1996 KAO, followed by IBM, 3M / Imation. Most of these companies have transferred production to third companies or switched to the newfangled practice of outsourcing today. Already in the mid-90s, all experts started talking about the fact that the speed, and most importantly, the capacity of floppy disks, no longer meets the needs of today. Consumption of standard floppy disks stabilized, and by the end of 2000, worldwide sales began to decline.

Sales of 3.5 "floppy disks in Europe (million units)

YEAR 1998 1999 2000 2001 2002

Sales 565 560 572 505 450

The situation in Russia turned out to be somewhat different. Here, the growth of the floppy disk market in quantitative terms continued until 2002. Now it is worth turning to the technical side of the issue. It is known that for each of the standard sizes of floppy disks (5.25 or 3.5 inches), special drives of the corresponding form factor were developed. Floppy disks of every standard size (5.25 and 3.5 inches) became double-sided (Double Sided, DS), and single-sided ones gradually ceased to be produced.

The recording density could be different:

• single (Single Density, SD);
• double (Double Density, DD);
• high (High Density, HD).

Since few people remember about single density, I will skip this classification, and will only talk about double-sided double-density floppies (DS / DD, capacity 360 or 720 KB) and double-sided high-density floppies (DS / HD, capacity 1,2, 1, 44 or 2.88 MB). The recording density of a floppy disk is determined by the size of the gap between the disc and the magnetic head, and the quality of the recording (reading) itself depends on the stability of the gap. To increase the density, it was vital to reduce the gap. However, at the same time, the requirements for the quality of the working surface of the floppy disk increased significantly. Aluminum alloy D16MP (MP - magnetic memory) began to be used as a material for the manufacture of magnetic disks.

The floppy disk itself was a layer of soft magnetic material deposited on a special substrate made of a non-magnetic polymer plastic substance, the degree of hardness of which could be different depending on the implementation. The carrier itself was placed in a paper, plastic or other casing-case. In the casing, the floppy disk was freely rotated by the floppy drive through the central grip window. This provided the passage of the track area under the read / write device - the read / write head. There were holes on the casing of the floppy disk:

• · Central grip;
• · Head positioning hole;
• · Physical write protection hole;
• · Guide holes and grooves;
• · Holes for automatic detection of the type of magnetic coating;
• · Hole for determining the complete revolution of the carrier;
• · The hole for positioning the magnetic read / write heads for 3.14 inch media is closed with a metal latch.
• · A hole for central grip and rotation on the spindle of the disk rotation drive (unlike media with a diameter of 5.25 inches, it is located only on the underside of the diskette).

Another fundamental innovation for its time was such an operation as formatting. Initially, floppy disks were formatted using special software, which is rather unusual for today's layman. Typically, floppy disk manufacturers specified a parameter called the number of dots per inch of the media - TRACK PER INCH (TPI). This parameter said what the maximum density of the arrangement of regions of independent magnetization can have a carrier.

The first floppy drives were huge! They were not located inside system unit, but were outside. The disk drive was universal device read / write. Each type of media, as a rule, required its own device - for reading 8 ", 5" and 3 "floppy disks. Such a drive consisted of a motor, a media rotation control system, a motor, a read / write head positioning control system, signal generation and conversion circuits and other electronic devices.

It remains from the above to conclude that the development of a conventional floppy disk has become one of the most important components of the success of personal computers.

(MO), which were a hard polymer disk, reading from which was performed by a laser, and writing - using the combined action of a laser (to heat a surface area) and a stationary magnet (to reverse the magnetization of the information layer). They are not completely magnetic, although they use cartridges shaped like floppy disks.

History

Floppy disk device 3½ ″

Iomega Zip

By the mid-90s, a floppy disk capacity of even 2.88 MB was no longer enough. Several formats pretended to replace the 3.5 ″ floppy, among which the most popular were the Iomega Zip floppy disks. Just like the 3.5 ″ floppy disk, the Iomega Zip media was a soft polymer disk covered with a ferromagnetic layer and enclosed in a hard case with a protective shutter. Unlike the 3.5 ″ diskette, the hole for the magnetic heads was located at the end of the case, and not on the side surface. There were Zip floppy disks for 100, 250, and by the end of the format's existence - and 750 MB. In addition to the larger volume, Zip drives provided more secure storage data and more high speed read and write than 3.5 ″. However, they were never able to supplant three-inch floppy disks due to the high price of both floppy drives and floppy disks, as well as due to unpleasant feature drives, when a floppy disk with mechanical damage to the disk disabled the disk drive, which, in turn, could spoil the floppy disk inserted into it after that.

Formats

Chronology of the emergence of floppy disk formats

Format	Year of origin	Volume in kilobytes
eight"		80
eight"		256
eight"		800
8 ″ double density		1000
5¼ ″		110
5¼ ″ double density		360
5¼ ″ Quadruple Density		720
5¼ "high density		1200
3 ″		360
3 ″ double density		720
3½ ″ double density		720
2 ″		720
3½ ″ high density		1440
3½ ″ expanded density		2880

It should be noted that the actual capacity of the floppy disks depends on how they are formatted. Since, except for the earliest models, virtually all floppy disks do not contain rigidly formed tracks, the path for experiments in the field of more efficient use of the floppy disk was open for system programmers. The result was the emergence of many incompatible floppy disk formats, even under the same operating systems.

Diskette formats in IBM hardware

The "standard" formats of IBM PC floppy disks differed in the size of the disk, the number of sectors per track, the number of sides used (SS stands for single-sided floppy, DS stands for double-sided), and the type (recording density) of the drive - the type of drive was marked:

• SD (English Single Density, single density, first appeared in the IBM System 3740),
• DD (English Double Density, double density, first appeared in IBM System 34),
• QD (English Quadruple Density, quadruple density, was used in domestic clones of Robotron-1910 - 5¼ "floppy disk 720 K, Amstrad PC, Neuron I9.66 - 5¼" floppy disk 640 K),
• HD (English High Density, high density, differed from QD by an increased number of sectors),
• ED (Extra High Density).

Additional (non-standard) tracks and sectors sometimes contained copy protection data of proprietary floppy disks. Standard programs such as diskcopy did not transfer these sectors when copying.

Working floppy densities and floppy capacities in kilobytes

Magnetic coating parameter	5¼ ″			3½ ″
	Double Density (DD)	Quadruple Density (QD)	High density (HD)	Double Density (DD)	High density (HD)	Extra high density (ED)
Base of the magnetic layer		Fe		Co	Co
Coercive force,	300	300	600	600	720	750
Magnetic layer thickness, microinch	100	100	50	70	40	100
Track width, mm	0,300		0,155	0,115	0,115	0,115
Track density per inch	48	96	96	135	135	135
Linear density	5876	5876	9646	8717	17434	34868
Capacity (after formatting)	360	720	1200 (1213952)	720	1440 (1457664)	2880

Pivot table floppy disk formats used in IBM PCs and compatible PCs

Disc diameter, ″	5¼ ″					3½ ″
Disk capacity, KB	1200	360	320	180	160	2 880	1 440	720
MS-DOS Media Description Byte	F9 16	FD 16	FF 16	FC 16	FE 16	F0 16	F0 16	F9 16
Number of sides (heads)	2	2	2	1	1	2	2	2
Number of tracks on each side	80	40	40	40	40	80	80	80
Number of sectors per track	15	9	8	9	8	36	18	9
Sector size, bytes	512
Number of sectors in a cluster	1	2	2	1	1	2	1	2
FAT length (in sectors)	7	2	1	2	1	9	9	3
FAT quantity	2	2	2	2	2	2	2	2
Root directory length in sectors	14	7	7	4	4	15	14	7
Maximum number of items in the root directory	224	112	112	64	64	240	224	112
The total number of sectors on the disk	2400	720	640	360	320	5 760	2 880	1 440
Number of sectors available	2371	708	630	351	313	5 726	2 847	1 426
Number of available clusters	2371	354	315	351	313	2 863	2 847	713

The first (more precisely, the 0th) is the lower head. In single-sided drives, only the bottom head is actually used, and the top head is replaced with a felt pad. At the same time, it was possible to use double-sided floppy disks on single-sided drives, formatting each side separately and turning it over if necessary, but in order to take advantage of this opportunity, a second index window had to be cut in a plastic envelope of an 8-inch floppy disk, symmetrically to the first.

All floppy drives have a spindle speed of 300 rpm, with the exception of a 5¼ "high density floppy disk drive that spins at 360 min −1.

Floppy disk formats in other foreign equipment

Additional confusion was caused by the fact that Apple used floppy drives in its Macintosh computers that use a different principle of encoding for magnetic recording than on the IBM PC - as a result, despite the use of identical floppies, the transfer of information between platforms on floppy disks was not possible until that moment. when Apple introduced high-density SuperDrives that worked in both modes.

A fairly common modification of the 3½ ″ floppy format is to format them at 1.2 MB (with a reduced number of sectors). This feature can usually be enabled in the BIOS of modern computers. This use of 3½ ″ is typical for Japan and South Africa. As a side effect, activating this BIOS setting will usually read floppies formatted with drivers like 800.com.

Features of using floppy disks in domestic technology

In addition to the above format variations, there were a number of improvements and deviations from the standard floppy disk format:

• for example, for RT-11 and its versions adapted in the USSR, the number of incompatible diskette formats in circulation exceeded a dozen. The most famous ones are those used in the DCK MX, MY;
• Also known are 320/360-kilobyte Iskra-1030 / Iskra-1031 floppy disks - in fact, they were SS / QD floppies, but their boot sector was marked as DS / DD. As a result, a standard IBM PC drive could not read them without using special drivers (such as 800.com), and the Iskra-1030 / Iskra-1031 drive, respectively, could not read standard DS / DD floppy disks from IBM PC;
• in computers of the ZX-Spectrum platform, 5.25 ″ and 3.5 ″ floppy disks were used, but their own unique TR-DOS format was used - 16 sectors per track, each sector of 256 bytes (instead of 512 bytes standard for the IBM PC). Both double-sided and single-sided floppy disks and floppy drives were supported. As a result, the data volume was 640 and 320 KB, respectively. The format only supports the root directory, which occupies only the first 8 sectors of the 0th track, in the 9th sector is system information about a floppy disk - type (TR-DOS or not), one or two-sided disk, the total number of files and the number of free sectors (not bytes, but sectors). Sectors 10 to 16 on track 0 are not used. All files are located only sequentially - the TR-DOS format has no idea about fragmentation, and the maximum file size is 64 KB. After deleting a file inside the occupied space, free sectors appear, which can no longer be occupied until the ″ Move ″ disk compacting command is executed. On IBM PC compatible computers, such floppy disks can only be read and written using special programs, for example ZX Spectrum Navigator v.1.14 or ZXDStudio.

In addition to the TR-DOS format, arbitrary disk formats were often used in ZX-Spectrum compatible computers. Some ezines and floppy disk games used their own format, which was not compatible with anything at all. They could use sectors of 512 bytes, and even 1024 bytes, and often combined different sizes of sectors on one track, for example, 256 and 1024 bytes, and just used for different tracks different formats... For example, this was done in the electronic magazine ZX-Format. Moreover, from issue number to issue, this magazine constantly changed the format of floppy disk tracks. This was done for two purposes: Firstly, to increase the amount of data on a floppy disk, and secondly, to protect floppy disks from pirated copying. Such floppy disks on ZX-Spectrum compatible computers of users could only be read, run a magazine or a game from them, but nothing could be copied. To copy such floppy disks, for each a separate room a ZX-Format magazine or a game, you had to write your own individual formatter and copier in assembler, having previously hacked the rest of the protection steps. Of course, such floppy disks cannot be read and copied on IBM PC compatible computers. Once I came across a generally unique format - except for the non-standard size of sectors on the track (5 sectors of 1024 bytes each), the numbers of all 5 sectors were the same. To run the software from such a floppy disk, a special bootloader was used, located on the first track after the directory with the standard TR-DOS format for the ZX-Spectrum. In ZX-Spectrum compatible computers, both 5.25 ″ and 3.5 ″ floppy disks were used in the same way, the format does not depend on the size of the floppy disk, nor on the density supported by it. But to use 3.5 ″ high density HD floppy disks, it was necessary to seal the side density window with electrical tape. 5.25 ″ HD floppy disks can be used in the ZX-Spectrum only if you use a drive that also supports HD density, but the drive must be jumpered to SD format (720 Kb).

The pu_1700 driver also allowed for shifting and sector interleaving, which accelerated sequential read-write operations, since the head would be in front of the first sector when moving to the next cylinder. When using normal formatting, when the first sector is always behind the index hole (5¼ ″) or behind the passage zone above the reed switch or Hall sensor of the magnet attached to the motor (3½ ″), during the head step, the beginning of the first sector has time to slip through, so the drive has to make extra turnover.

Special BIOS extender drivers (800, pu_1700, vformat and others) allowed formatting floppy disks with an arbitrary number of tracks and sectors. Since floppy drives usually supported from one to four additional tracks, and also allowed, depending on design features, to format 1-4 sectors per track more than the standard, these drivers provided the appearance of such non-standard formats as 800 KB (80 tracks , 10 sectors), 840 KB (84 tracks, 10 sectors), etc. The maximum capacity consistently achieved with this method on 3½ ″ HD drives was 1700 KB. This technique was subsequently used in the DMF floppy formats.

A little more than forty years ago, the first computer floppy disks appeared, and thirty years ago the well-known 3.5-inch floppy disks came out. And they are still being produced! Nowadays, to transfer information, they use flash drives and external hard drives, and all previous developments are already almost consigned to oblivion. IT. TUT.BY studied what removable media were left noticeable footprint in computer history, and which could become the standard for many years to come.

Here we will consider only floppy disks and cartridges with magneto-optical disks that were inserted into readers, and regular discs and we will not disassemble streamers with magnetic tape.

Floppy Disk 8 "(Floppy Disc)

Developer: IBM

Year of issue: 1971

Dimensions: 200x200x1 mm

Size: from 80 Kb at the beginning of the release to 1.2 Mb

Distribution: ubiquitous

In 1967, IBM under the leadership of Alan Shugart organized a group to develop new floppy disks. In 1971, the first eight-inch floppy disk was launched on the market: a round flat floppy disk in a plastic envelope measuring 20x20 cm. Due to its flexibility, the novelty was named Floppy Disc - "floppy disk". At first, the capacity was only 80 kilobytes, but over time, the recording density was increased, and after five years the floppy disks could already contain more than a megabyte of information.

5.25 "Diskette (Mini Floppy Disk)

Developer: Shugart Associates

Year of issue: 1976

Dimensions: 133x133x1 mm

Size: from 110 Kb at the beginning of the release to 1.2 Mb

Data exchange rate: up to 63 Kb / s

Distribution: ubiquitous

Two years after the release of the first eight-inch floppy disks, Alan Shugart founds his own company Shugart Associates, which three years later introduced new development- a five-inch floppy disk and a floppy drive. The company also noted the development of the SASI standard, which was later renamed SCSI. Floppy disks were single-sided and double-sided, and many computer designers used their own formatting and writing algorithms, which made discs written in one drive unreadable in another. Schoolchildren of the period of the decline of the USSR and the first years of independence of the union republics loaded computers from such floppy disks and played the simplest games. By the mid-eighties, the capacity of floppy disks had been increased tenfold. And Shugart Associates, by the way, later changed its name to the well-known Seagate.

Floppy disk 3,5 "(Micro Floppy Disk)

Developer: Sony

Year of issue: 1981

Dimensions: 93x89x3 mm

Size: from 720 KB at the beginning of the release to 1.44 MB (standard), up to 2.88 MB (Extended Density)

Data exchange rate: up to 63 Kb / s

Distribution: ubiquitous

In 1981, Sony offers a completely the new kind floppy disks: three-inch. They weren't really flexible anymore, but the name remained. Now the magnetic circle was enclosed in plastic three millimeters thick, and the hole for the heads was covered with a curtain on a spring. These shutters, especially metal ones, loosened and bent during operation, and often came off inside the drive and remained there. Floppy disks became very popular, and various computer manufacturers equipped their machines with them. Sony has produced several models of digital cameras, which were recorded on floppy disks. By 1987, the standard capacity of floppy disks had grown to 1.44 MB, and a little later, thanks to an even higher recording density, it was possible to "squeeze out" up to 2.88 MB. Savvy students in dormitories (including Belarusian ones) for money "overclocked" floppies up to 1.7-1.8 MB, while they could be read in conventional drives... In spite of everything, three-inch floppy disks are still produced. Floppy disks are almost obsolete, but many programs still use the "Save" icon in the form of a floppy disk.

Amstrad Disc 3 "(Compact Floppy Disc, CF2)

Developer: Hitachi, Maxell, Matsushita

Year of issue: 1982

Dimensions: 100x80x5 mm

Size: from 125 Kb at the beginning of the release to 720 Kb

Distribution: quite wide - mainly computers Amstrad CPC and Amstrad PCW, also Tatung Einstein, ZX Spectrum +3, Sega SF-7000, Gavilan SC

Amstrad, a renowned computer manufacturer, decided to go its own way and promoted a different 3-inch floppy disk from Hitachi. Even more surprising is the fact that the company was founded by the same Alan Shugart, who developed the first floppy disks. The magnetic disk itself inside the case took up less than half of the free space - the rest fell on the media protection mechanisms, which is why the cost of these disks was quite high. Although these floppy disks were more expensive than standard 3.5-inch floppy disks with less memory, the company has been promoting them for quite some time and succeeded: more than 3 million Amstrad CPC computers have been produced alone.

Bernoulli box

Developer: Iomega

Year of issue: 1983

Dimensions: Bernoulli Box: 27.5x21 cm, Bernoulli Box II: 14x13.6x0.9 cm

Size: from 5 MB at the beginning of the release to 230 MB

Data transfer rate: up to 1.95 Mb / s

Distribution: small

Iomega, later one of the main "whales" of the removable media market, developed the original Bernoulli Box in 1983. In it, the floppy disk rotates at a high speed (3000 rpm), as a result of which the surface of the disk directly under the read head bends and does not come into contact with it: read / write operations are performed through an air cushion. The equations for describing these air currents were proposed by the prominent Swiss scientist Daniel Bernoulli in the 18th century. Thanks to this development, the company gained fame, although the first products did not differ in either capacity or portability: the first cartridges were 27.5x21 cm in size and contained only 5 megabytes of information. The second generation decreased in size by about four times, and the amount of memory by 1994 had grown to 230 megabytes. But by that time, magneto-optical disks began to be actively promoted.

Magneto-optical drive (MO)

Developer: Sony

Year of issue: 1985

Dimensions: 133x133x6 mm, 93x89x6 mm, 72x68x5 mm for MiniDisc

Volume: 650 MB to 9.2 GB for 5-inch, 128 MB to 2.3 GB for 3.5-inch, 980 MB for mini-disks

Data exchange rate: up to 10 Mb / s

Distribution: significant

Magneto-optical discs look like standard and reduced-size CDs in a box. But at the same time they have an important difference: the recording is carried out in a magnetic way, that is, first, the laser heats the surface to a high temperature, and then the magnetization of the sections changes with an electromagnetic pulse. The system possesses great reliability and resistance to mechanical damage and magnetic radiation, but it provided a low recording speed and had a high power consumption. Both disks and drives were expensive, so magneto-optics did not receive very wide distribution like compact disks. Distribution was also hindered by the fact that for a very long time such discs allowed recording data only once. But in some industries (for example, medicine), where the preservation of a large amount of information is required for a long time (and MO-disks "live" up to 50 years), the technology has gained acceptance. Sony still produces magneto-optical discs in both small and large sizes. MiniDisc music discs presented by the same Sony company in 1992 - special case magneto-optical disks. If at first they allowed recording only music, then modifications MD Data (1993) and Hi-MD (2004) provide recording of any data with a volume of 650 MB and 980 MB, respectively. "Minidisks" are still in production too.

Wheels SyQuest

Developer: SyQuest

Year of issue: around 1990

Dimensions: 5.25 "(approx. 13x13 cm) and 3.5" (approx. 9x9 cm)

Sizes: 5.25 ": 44, 88 and 200 MB; 3.5": 105 and 270 MB

Distribution: Medium (predominantly with MacIntosh computers)

Founded in 1982 by former Seagate employee Syed Iftikar, QyQuest entered the market with removable hard drives for the IBM XT. The firm later developed several different cartridge disk systems. The most popular are the 5.25-inch SQ400 / SQ800 / SQ2000 cartridges (44, 88 and 200 MB), as well as the 3.5-inch SQ310 / SQ327 (105 and 270 MB). Their main disadvantage, apart from size, was that later systems were not fully compatible with earlier ones. Thus, drives for 200MB discs could only read 88MB discs, but could not write to them. The younger systems could neither read nor write to the older ones. In the year of release, 44MB drives cost about $ 100. A variety of incompatible standards and the absence of a normal trade name for a particular technology did not allow the discs to gain wide popularity. Magneto-optical disks provided more capacity, and Iomega's Zip disks soon followed.

Floptical

Developer: Insite Peripherals

Year of issue: 1991 (Insite Floptical), 1998 (Caleb UHD144, Sony HiFD)

Dimensions: 93x89x3 mm

Size: 21 MB (Insite Floptical), 144 MB (Caleb UHD144), 150-200 MB (Sony HiFD)

Data exchange rate: up to 125 Kb / s

Distribution: very small

Another magneto-optical technology, but of a different kind. The information is read by the magnetic heads, and the optical subsystem (infrared LEDs) ensures the accuracy of the head positioning. Thus, instead of the usual 135 tracks per inch, like floppy disks, they achieved a recording density of 1250 tracks per inch. Floptical drives were compatible with regular 3.5-inch floppies, and Floptical drives were initially marketed as the successor to floppy disks, but this did not happen. Seven years later, Caleb Technology developed a similar system, the Caleb UHD144, and Sony released Sony HiFD discs. Both of these systems were also compatible with regular floppy disks and both were also named as floppy disks, but they faced a loud failure in the market, because by that time the market for removable media of 100-250 MB was taken over by Iomega Zip disks.

Zip Drive (Iomega Zip)

Developer: Iomega

Year of issue: 1994

Dimensions: 98x98x6 mm

Volume: from 100 MB at the beginning of the release to 750 MB

Data exchange rate: about 1 Mb / s

Spread: very wide

Compact disks were still expensive and did not allow erasing records (CD-RWs appeared only in 1997), magneto-optical disks were expensive and gluttonous, and the capacity of ordinary floppy disks was no longer enough. Iomega has refined the magnetic recording technology and introduced Zip disks: slightly larger than floppy disks, and with a capacity of as much as 100 megabytes. The head was brought to the disk not from the top, but from the side, and the data exchange rate was about 15 times faster than that of conventional floppy disks. Disk drives were produced in several formats - both external and internal, graceful in shape and blue, which could be placed on a table flat or vertically. The technology quickly gained popularity. Despite the "clicks of death" which were a sign of disk failure, the zips sold successfully. In the year of release, floppy drives cost $ 100 and discs $ 20 each; later, 250-megabyte disks (rounded, but of the same dimensions) and 750-megabytes (of the usual shape) appeared. Since the beginning of the 2000s, the popularity of Zip-drives has declined, but Iomega still sells 100-megabyte drives at $ 9 apiece, and "seven hundred and fifty" - at $ 12.5. Many ancient technology enthusiasts still use epoch-making devices.

<Продолжение следует>

The other uses (used) special external media (floppy disks and disks). Naturally, technologies do not stand still and more and more new devices are being invented, or old ones are being improved in terms of data transfer speed and memory capacity.

In this article we will look at how and when the first disks, floppy disks appeared, as well as their main characteristics and features.

Floppy disk 8 "(inches)- In 1971, an 8-inch floppy disk and a floppy disk drive were introduced for the first time. This diskette was released by IBM. The disc itself consists of a magnetically coated polymer material in a plastic wrap. Depending on the number of sectors, such floppy disks had different sizes and were subdivided into 80 kb, 256 kb and 800 kb.

5.25 "Floppy Disk - In 1976, Shugart Associates designed and manufactured the 5.25" floppy disk drive and floppy disks. 5-inch floppy disks quickly gained popularity and supplanted their predecessors. This floppy disk was not much different from the 8-inch parents, except that it was smaller in size, the plastic cover was stiffer, and the edges of the drive hole were reinforced with a plastic ring. Such disks (depending on the format) contained 110, 360, 720 or 1200 kilobytes of data.

3.5 ”Floppy Disk - In 1981, Sony introduced the 3.5” floppy disk for the first time. This diskette was already specifically different from the previous ones. The floppy disk was covered with a hard case, in the center of the floppy disk there was a metal sleeve, which allowed it to be correctly positioned in the disk drive. Floppy disks were mostly 1.44 MB, but there were 720 kb, as well as 2.88 MB. This type of floppy disk has survived the most on the market and is even still used in many structures and institutions.

Iomega ZIP - In the mid-90s, 3.5-inch floppy disks were replaced by ZIP disks. Outwardly, they resembled 3.5 ”floppy disks, but were slightly thicker. They were supposed to replace the previous generation, as 1.44 MB was no longer enough to store data. ZIP disks were released in sizes of 100 MB and 250 MB (At sunset, even 750 MB were met). But the disks did not gain popularity, since the drives and the disks themselves were very expensive, so people remained loyal to their 3.5 ”comrades.

COMPACT DISCS (CD-ROM / CD-RW / DVD-ROM / DVD + R / DWD-R / DVDRWBlueRay)

The CD was first developed by Sony as early as 1979, and mass production of these discs began in 1982. Initially, they wanted to use CDs only for audio recordings, but later they began to store all digital data on them. Vice President Sony insisted that Beethoven's ninth symphony, which took 74 minutes (under the direction of Wilhelm Furtwängler), could fully fit on the disk, then any classical work would fit on such a disk. If we take the amount of data, then such a floppy disk contained 650 MB. Starting somewhere in 2000, 700 MB (80 minutes) disks began to be produced.

The disc itself consists of polycarbonate coated with a thin layer of metal (aluminum, silver), which in turn is covered with a thin layer of varnish.

In 1988, the format appears CD-R(Recordable - Recordable). This is the same CD, but empty, in other words "Blank". Any information could be recorded on it, but then it was impossible to delete it from the disk.

In 1997, the format appears CD-RW(ReWritable - Rewritable). This is also the same CD-R, only now the data from it could be erased and others written.

DVD(Digital Video Disk) - the disc had the same dimensions as a regular CD and externally was no different, but had a more dense structure. The first discs appeared in Japan in 1996, and their volume was 1.46 GB (DVD-1), which was twice as much as regular CDs. The most popular are the 4.7 GB DVD (DVD-5). The maximum capacity for a DVD is 17.08 GB (DVD-18).

DVD-R- The first DVD-R was released in 1997 at a price of $ 50 and a volume of 3.95 GB. Many people ask the question: what is the difference between DVD-R and DVD + R? Everything is very simple. You cannot erase information from both of them, but you can write on "+" before, and you cannot write on "-".

DVD-RAM- Rewritable discs, but unlike DVD-RW, they can be rewritten at least 100,000 times (the usual ones are designed for 1,000). Also, information is read much faster and writing to it is like a removable HDD, i.e. without additional software. Of course, such a disc is more expensive, and even not all players can read it.

BD (BlueRay Disc)- a disc with a higher density than DVD. Mainly designed to record high definition movies there. The disc was first introduced to the general public in 2006. Its volume is 25 GB (single layer) and 50 GB (dual layer). Mini BD 7.8 GB are also available.