Digital Data Storage
Digital Data Storage is a computer data storage technology, based upon the digital audio tape format, developed during the 1980s. DDS is intended for use as off-line storage for generating backup copies of working data. A DDS cartridge uses tape with a width of 3.81mm, with the exception of the latest formats, DAT-160 and DAT-320, both which use 8mm wide tape. The tape was 60 meters or 90 meters in length. Advancements in materials technology have allowed the length to be increased in successive versions. A DDS tape drive uses the same process used by a video cassette recorder. Backward compatibility between newer drives and older cartridges is not assured. Drives can read and write tapes in the prior generation format, with most able to read and write tapes from two generations prior. Notice in HP's article that newer tape standards do not consist of longer tapes. At one time, DDS competed against the Linear Tape-Open, Advanced Intelligent Tape, VXA, Travan formats. However, AIT, Travan and VXA are no longer mainstream, the capacity of LTO has far exceeded that of the most recent DDS standard, DDS-320.
Stores up to 1.3 GB uncompressed on 2 GB uncompressed on a 90 m cartridge. The DDS-1 cartridge does not have the -1 designation, as it was the only format, though cartridges produced since the introduction of DDS-2 may carry a -1 designation to distinguish the format from newer formats. A media recognition system was introduced with DDS-2 drives and cartridges to detect the medium type and prevent the loading of an improper medium. From 1993, DDS-1 tapes included the media recognition system marks on the leader tape—a feature indicated by the presence of four vertical bars after the DDS logo. Stores up to 4 GB uncompressed on a 120 m cartridge. Stores up to 12 GB uncompressed on a 125 m cartridge. DDS-3 uses PRML to minimize electronic noise for a cleaner data recording. DDS-4 stores up to 20 GB uncompressed on a 150 m cartridge; this format is called DAT 40. DAT 72 stores up to 36 GB uncompressed on a 170 m cartridge; the DAT 72 standard was developed by Certance. It has the same form-factor as DDS-3 and -4 and is sometimes referred to as DDS-5.
DAT 160 was launched in June 2007 by HP, stores up to 80 GB uncompressed. A major change from the previous generations is the width of the tape. DAT 160 uses 8 mm wide tape in a thicker cartridge while all prior versions use 3.81 mm wide tape. Despite the difference in tape widths, DAT 160 drives can load DAT-40 cartridges. Native capacity is 80 GB and native transfer rate was raised to 6.9 MB/s due to prolonging head/tape contact to 180°. Launch interfaces were Parallel USB, with SAS interface released later. In November 2009 HP announced the DAT-320 standard, which stores up to 160 GB uncompressed per cartridge; the next format, Gen 8, was canceled. ECMA-139 ISO/IEC 10777:1991, Specification of DDS. ECMA-146 ISO/IEC 11321:1992, Specification of DATA/DAT. ECMA-150 ISO/IEC 11557:1992, Specification of DDS-DC. ECMA-151 ISO/IEC 11558:1992, Specification of DCLZ. ECMA-170 ISO/IEC 12447:1993, Specification of DDS. ECMA-171 ISO/IEC 12448:1993, Specification of DATA/DAT-DC. ECMA-198 ISO/IEC 13923, Specification of DDS-2.
ECMA-236 ISO/IEC 15521, Specification of DDS-3. ECMA-288 ISO/IEC 17462, Specification of DDS-4. Digital Audio Tape Magnetic storage Magnetic tape DAT Manufacturers Group
A tape transport is the collection of parts of a magnetic tape player or recorder that the actual tape passes through. Transport parts include the head, pinch roller, tape pins, tape guide; the tape transport as a whole is called the transport mechanism. The capstan is a rotating spindle used to move recording tape through the mechanism of a tape recorder; the tape is threaded between the capstan and one or more rubber-covered wheels, called pinch rollers, which press against the capstan, thus providing friction necessary for the capstan to pull the tape. The capstan is always placed downstream from the tape heads. To maintain the required tension against the tape heads and other part of the tape transport, a small amount of drag is placed on the supply reel. Tape recorder capstans have a function similar to nautical capstans, which however have no pinch rollers, the line being wound around them; the use of a capstan allows the tape to run at a constant speed. Capstans are precision-machined spindles, polished smooth: any out-of-roundness or imperfections can cause uneven motion and an audible effect called flutter.
The alternative to capstan drive driving the tape takeup reel, causes problems both with the speed difference between a full and empty reel and with speed variations as described. Dual capstans, where one is on each side of the heads, are claimed to provide smoother tape travel across the heads and result in less variance in the recorded/playback signal; the pinch roller is a rubberized, free-spinning wheel used to press magnetic tape against a capstan shaft in order to create friction necessary to drive the tape along the magnetic heads. Most magnetic tape recorders use one capstan motor and one pinch roller located after the magnetic heads in the direction of the moving tape; however multiple pinch rollers may be employed in association with one or more capstans. An example of the application of multiple pinch rollers is the Technics-RS1520 tape recorder, which utilizes two pinch rollers located on opposite sides of a single capstan shaft, providing a more stable transport across two sets of magnetic heads.
Dual pinch rollers are used in auto-reverse cassette decks to drive the tape in both directions as needed. In this case, only one pinch roller is pressed against its corresponding capstan at a time. A tension arm is a device used in magnetic tape recorders/reproducers to control the tension of the magnetic tape during machine operation; the recorders equipped with a tension arm can utilize more than one of them to control tape tension in different direction of winding or during different modes of tape operation. Tension arms can be found on digital data recorders and other types of recorders/reproducers using continuous tape media such as magnetic digital tape, perforated paper tape, analog magnetic tape. One of many US Patents pertaining to Tension arm Workbench Guide to Tape Recorder Servicing. G. Howard Poteet, 1977
Fibre Channel is a high-speed data transfer protocol providing in-order, lossless delivery of raw block data used to connect computer data storage to servers. Fibre Channel is used in storage area networks in commercial data centers. Fibre Channel networks form a switched fabric. Fibre Channel runs on optical fiber cables within and between data centers, but can run on copper cabling. Most block storage supports many upper level protocols. Fibre Channel Protocol is a transport protocol that predominantly transports SCSI commands over Fibre Channel networks. Mainframe computers run the FICON command set over Fibre Channel because of its high reliability and throughput. Fibre Channel can be used to transport data from storage systems that use solid-state flash memory storage medium by transporting NVMe protocol commands; when the technology was devised, it ran over optical fiber cables only and, as such, was called "Fiber Channel". The ability to run over copper cabling was added to the specification.
In order to avoid confusion and to create a unique name, the industry decided to change the spelling and use the British English fibre for the name of the standard. Fibre Channel is standardized in the T11 Technical Committee of the International Committee for Information Technology Standards, an American National Standards Institute -accredited standards committee. Fibre Channel started in 1988, with ANSI standard approval in 1994, to merge the benefits of multiple physical layer implementations including SCSI, HIPPI and ESCON. Fibre Channel was designed as a serial interface to overcome limitations of the SCSI and HIPPI interfaces. FC was developed with leading edge multi-mode optical fiber technologies that overcame the speed limitations of the ESCON protocol. By appealing to the large base of SCSI disk drives and leveraging mainframe technologies, Fibre Channel developed economies of scale for advanced technologies and deployments became economical and widespread. Commercial products were released.
By the time the standard was ratified lower speed versions were growing out of use. Fibre Channel was the first serial storage transport to achieve gigabit speeds where it saw wide adoption, its success grew with each successive speed. Fibre Channel has doubled in speed every few years since 1996. Fibre Channel has seen active development since its inception, with numerous speed improvements on a variety of underlying transport media; the following table shows the progression of native Fibre Channel speeds: In addition to a modern physical layer, Fibre Channel added support for any number of "upper layer" protocols, including ATM, IP and FICON, with SCSI being the predominant usage. Two major characteristics of Fibre Channel networks is that they provide in-order and lossless delivery of raw block data. Lossless delivery of raw data block is achieved based on a credit mechanism. There are three major Fibre Channel topologies, describing how a number of ports are connected together. A port in Fibre Channel terminology is any entity that communicates over the network, not a hardware port.
This port is implemented in a device such as disk storage, a Host Bus Adapter network connection on a server or a Fibre Channel switch. Point-to-point. Two devices are connected directly to each other; this is the simplest topology, with limited connectivity. Arbitrated loop. In this design, all devices are in a ring, similar to token ring networking. Adding or removing a device from the loop causes all activity on the loop to be interrupted; the failure of one device causes a break in the ring. Fibre Channel hubs may bypass failed ports. A loop may be made by cabling each port to the next in a ring. A minimal loop containing only two ports, while appearing to be similar to point-to-point, differs in terms of the protocol. Only one pair of ports can communicate concurrently on a loop. Maximum speed of 8GFC. Arbitrated Loop has been used after 2010. Switched Fabric. In this design, all devices are connected to Fibre Channel switches, similar conceptually to modern Ethernet implementations. Advantages of this topology over point-to-point or Arbitrated Loop include: The Fabric can scale to tens of thousands of ports.
The switches manage the state of the Fabric, providing optimized paths via Fabric Shortest Path First data routing protocol. The traffic between two ports flows through the switches and not through any other ports like in Arbitrated Loop. Failure of a port should not affect operation of other ports. Multiple pairs of ports may communicate in a Fabric. Fibre Channel does not follow the OSI model layering, is split into five layers: FC-4 – Protocol-mapping layer, in which upper level protocols such as NVMe, SCSI, IP or FICON, are encapsulated into Information Units for delivery to FC-2. Current FC-4s include FCP-4, FC-SB-5, FC-NVMe. FC-3 – Common services layer, a thin layer that could implement functions like encryption or RAID redundancy algorithms. Layers FC-0 are defined in Fibre Channel Physical Interfaces, the
9 track tape
The IBM System/360, released in 1964, introduced what is now known as 9 track tape. The ½ inch wide magnetic tape media and reels are the same size as the earlier IBM 7 track format it replaced, but the new format has eight data tracks and one parity track for a total of nine parallel tracks. Data is stored as 8-bit characters. Various recording methods were employed during its lifetime as tape speed and data density increased, including PE, GCR and NRZI. Tapes came in various sizes up to 3,600 feet in length; the standard size of a byte was set at eight bits with the S/360 and nine-track tape. For over 30 years the format dominated offline storage and data transfer, but by the end of the 20th century it was obsolete, the last manufacturer of tapes ceased production in early 2002, with drive production ending the next year. A typical 9-track unit consisted of a tape transport—essentially all the mechanics that moved tape from reel to reel past the read/write and erase heads—and supporting control and data read/write electronics.
The transport consisted of supply motor, take-up motor, hubs for locking the tape reels in place, a capstan motor, tape head assembly, miscellaneous rollers which kept the tape in a precise path during operation, vacuum columns which prevented tape'snatch'. Data could become corrupted by stretched tape or variations in tape speed, so the transport had to guide the tape through without damaging its edges, move it with minimal wow and flutter, give it a tension, low but sufficient to keep the tape in constant contact with the read/write head. To load a tape, an operator would remove the protective ring from the outside of the tape reel and install the tape on the supply hub thread the tape leader through the various roller assemblies and onto the take-up reel, installing three or four winds of tape to provide enough friction for the take-up motor to be able to pull the tape; the operator initiated an automatic sequence by a single press of a button, that would start the vacuum system move the tape forward until the beginning-of-tape foil strip was detected by an optical sensor in the tape path.
The control electronics would indicate to the controlling computer that the unit was ready for operation. Like its audio counterpart, moving tape past the read/write heads on nine-track digital required precise control, accomplished by a capstan motor; the capstan motor was designed for smooth operation. Feedback to the control electronics was accomplished by a tachometer an optical "tone wheel", to control tape velocity. Starting and stopping the capstan was controlled by ramp generators to ensure a properly sized inter-record gap, the gap between blocks of information; the vacuum system provided a physical buffer between the precision movements of the capstan and the large movements of the reels by storing a short length of tape in the vacuum column under low tension. The vacuum columns were chambers open at one end, the openings being in line with the tape path before and after the capstan and roller assemblies; the amount of tape in the column was controlled by four optical or vacuum sensors on the sides of the columns.
The control electronics kept the curve of the tape loop between the two inner sensors, cueing the supply reel to feed more or the take-up reel to take more as necessary. The outer two sensors, at the top and bottom of the columns, served to sense malfunctions in the feed mechanism during operation, prompting the control electronics to shut off all operation of the tape transport and vacuum system to prevent damaging the tape; because of the tension provided by the vacuum columns and the design of the tape path, tape was kept in sufficient contact with the high-friction coating on the capstan that a pinch roller was not used. Tape motion on many systems was bidirectional, i.e. tape could be read either forward or backward at the request of the controlling computer. Because the supply vacuum column kept a small, constant tension in the reverse direction, the capstan could feed backwards without the tape bunching up or jumping out of path. Unlike most audio tape systems, the capstan and head assemblies were always in contact with the tape during fast forward and reverse operations, only moving the head assembly away from the tape path during high-speed rewind.
On some units, manufacturers installed a "fast search" capability which could move the tape a certain number of blocks bring the tape to a halt and go back to read the requested data at normal speed. Tapes included an end-of-tape foil strip; when EOT was encountered while writing, the computer program would be notified of the condition. This gave the program a chance to write end-of-tape information on the tape while there was still enough tape to do so; the sensing of BOT and EOT was achieved by shining a small lamp at the tape's surface at an oblique angle. When the foil strip moved past the lamp a photo-receptor would see the reflected flash of light and trigger the system to halt tape motion; this is the main reason that photographic flash cameras were not allowed in data centers since they could trick the tape drives into falsely sensing BOT and EOT. The above describes a typical transport system. For example, some designs used a horizontal transport deck where the operator set the tape reel in
Serial ATA is a computer bus interface that connects host bus adapters to mass storage devices such as hard disk drives, optical drives, solid-state drives. Serial ATA succeeded the earlier Parallel ATA standard to become the predominant interface for storage devices. Serial ATA industry compatibility specifications originate from the Serial ATA International Organization which are promulgated by the INCITS T13 subcommittee ATA Attachment SATA was announced in 2000 in order to provide several advantages over the earlier PATA interface such as reduced cable size and cost, native hot swapping, faster data transfer through higher signaling rates, more efficient transfer through an I/O queuing protocol. Serial ATA industry compatibility specifications originate from the Serial ATA International Organization; the SATA-IO group collaboratively creates, reviews and publishes the interoperability specifications, the test cases and plugfests. As with many other industry compatibility standards, the SATA content ownership is transferred to other industry bodies: the INCITS T13 subcommittee AT Attachment, the INCITS T10 subcommittee, a subgroup of T10 responsible for Serial Attached SCSI.
The remainder of this article strives to use specifications. Before SATA's introduction in 2000, PATA was known as ATA; the "AT Attachment" name originated after the 1984 release of the IBM Personal Computer AT, more known as the IBM AT. The IBM AT’s controller interface became a de facto industry interface for the inclusion of hard disks. "AT" was IBM's abbreviation for "Advanced Technology". However, the ATA specifications use the name "AT Attachment", to avoid possible trademark issues with IBM. SATA host adapters and devices communicate via a high-speed serial cable over two pairs of conductors. In contrast, parallel ATA uses a 16-bit wide data bus with many additional support and control signals, all operating at a much lower frequency. To ensure backward compatibility with legacy ATA software and applications, SATA uses the same basic ATA and ATAPI command sets as legacy ATA devices. SATA has replaced parallel ATA in consumer laptop computers. PATA has been replaced by SATA for any use. A 2008 standard, CFast to replace CompactFlash is based on SATA.
The Serial ATA Spec requires SATA device hot plugging. After insertion, the device initializes and operates normally. Depending upon the operating system the host may initialize resulting in a hot swap; the powered host or device are not in a quiescent state. Unlike PATA, both SATA and eSATA support hotplugging by design. However, this feature requires proper support at the host and operating-system levels. In general, all SATA devices support hotplugging most SATA host adapters support this function. For eSATA function, Hot Plug function is supported in AHCI mode only. IDE mode does not support Hot Plug function. Advanced Host Controller Interface is an open host controller interface published and used by Intel, which has become a de facto standard, it allows the use of advanced features of SATA such as native command queuing. If AHCI is not enabled by the motherboard and chipset, SATA controllers operate in "IDE emulation" mode, which does not allow access to device features not supported by the ATA standard.
Windows device drivers that are labeled as SATA are running in IDE emulation mode unless they explicitly state that they are AHCI mode, in RAID mode, or a mode provided by a proprietary driver and command set that allowed access to SATA's advanced features before AHCI became popular. Modern versions of Microsoft Windows, Mac OS X, FreeBSD, Linux with version 2.6.19 onward, as well as Solaris and OpenSolaris, include support for AHCI, but earlier operating systems such as Windows XP do not. In those instances, a proprietary driver may have been created for a specific chipset, such as Intel's. SATA revisions are designated with a dash followed by roman numerals, e.g. "SATA-III", to avoid confusion with the speed, always displayed in Arabic numerals, e.g. "SATA 6 Gbit/s". Revision 1.0a was released on January 7, 2003. First-generation SATA interfaces, now known as SATA 1.5 Gbit/s, communicate at a rate of 1.5 Gbit/s, do not support Native Command Queuing. Taking 8b/10b encoding overhead into account, they have an actual uncoded transfer rate of 1.2 Gbit/s.
The theoretical burst throughput of SATA 1.5 Gbit/s is similar to that of PATA/133, but newer SATA devices offer enhancements such as NCQ, which improve performance in a multitasking environment. During the initial period after SATA 1.5 Gbit/s finalization and drive manufacturers used a "bridge chip" to convert existing PATA designs for use with the SATA interface. Bridged drives have a SATA connector, may include either or both kinds of power connectors, and, in general, perform identically to their native-SATA equivalents. However, most bridged drives lack support for some SATA-specific features such as NCQ
A floppy disk known as a floppy, diskette, or disk, is a type of disk storage composed of a disk of thin and flexible magnetic storage medium, sealed in a rectangular plastic enclosure lined with fabric that removes dust particles. Floppy disks are written by a floppy disk drive. Floppy disks as 8-inch media and in 5 1⁄4-inch and 3 1⁄2 inch sizes, were a ubiquitous form of data storage and exchange from the mid-1970s into the first years of the 21st century. By 2006 computers were manufactured with installed floppy disk drives; these formats are handled by older equipment. The prevalence of floppy disks in late-twentieth century culture was such that many electronic and software programs still use the floppy disks as save icons. While floppy disk drives still have some limited uses with legacy industrial computer equipment, they have been superseded by data storage methods with much greater capacity, such as USB flash drives, flash storage cards, portable external hard disk drives, optical discs, cloud storage and storage available through computer networks.
The first commercial floppy disks, developed in the late 1960s, were 8 inches in diameter. These disks and associated drives were produced and improved upon by IBM and other companies such as Memorex, Shugart Associates, Burroughs Corporation; the term "floppy disk" appeared in print as early as 1970, although IBM announced its first media as the "Type 1 Diskette" in 1973, the industry continued to use the terms "floppy disk" or "floppy". In 1976, Shugart Associates introduced the 5 1⁄4-inch FDD. By 1978 there were more than 10 manufacturers producing such FDDs. There were competing floppy disk formats, with hard- and soft-sector versions and encoding schemes such as FM, MFM, M2FM and GCR; the 5 1⁄4-inch format displaced the 8-inch one for most applications, the hard-sectored disk format disappeared. The most common capacity of the 5 1⁄4-inch format in DOS-based PCs was 360 KB, for the DSDD format using MFM encoding. In 1984 IBM introduced with its PC-AT model the 1.2 MB dual-sided 5 1⁄4-inch floppy disk, but it never became popular.
IBM started using the 720 KB double-density 3 1⁄2-inch microfloppy disk on its Convertible laptop computer in 1986 and the 1.44 MB high-density version with the PS/2 line in 1987. These disk drives could be added to older PC models. In 1988 IBM introduced a drive for 2.88 MB "DSED" diskettes in its top-of-the-line PS/2 models, but this was a commercial failure. Throughout the early 1980s, limitations of the 5 1⁄4-inch format became clear. Designed to be more practical than the 8-inch format, it was itself too large. A number of solutions were developed, with drives at 2-, 2 1⁄2-, 3-, 3 1⁄4-, 3 1⁄2- and 4-inches offered by various companies, they all shared a number of advantages over the old format, including a rigid case with a sliding metal shutter over the head slot, which helped protect the delicate magnetic medium from dust and damage, a sliding write protection tab, far more convenient than the adhesive tabs used with earlier disks. The large market share of the well-established 5 1⁄4-inch format made it difficult for these diverse mutually-incompatible new formats to gain significant market share.
A variant on the Sony design, introduced in 1982 by a large number of manufacturers, was rapidly adopted. The term floppy disk persisted though style floppy disks have a rigid case around an internal floppy disk. By the end of the 1980s, 5 1⁄4-inch disks had been superseded by 3 1⁄2-inch disks. During this time, PCs came equipped with drives of both sizes. By the mid-1990s, 5 1⁄4-inch drives had disappeared, as the 3 1⁄2-inch disk became the predominant floppy disk; the advantages of the 3 1⁄2-inch disk were its higher capacity, its smaller size, its rigid case which provided better protection from dirt and other environmental risks. If a person touches the exposed disk surface of a 5 1⁄4-inch disk through the drive hole, fingerprints may foul the disk—and the disk drive head if the disk is subsequently loaded into a drive—and it is easily possible to damage a disk of this type by folding or creasing it rendering it at least unreadable; however due to its simpler construction the 5 1⁄4-inch disk unit price was lower throughout its history in the range of a third to a half that of a 3 1⁄2-inch disk.
Floppy disks became commonplace during the 1980s and 1990s in their use with personal computers to distribute software, transfer data, create backups. Before hard disks became affordable to the general population, floppy disks were used to store a computer's operating system. Most home computers from that period have an elementary OS and BASIC stored in ROM, with the option of loading a more advanced operating system from a floppy disk. By the early 1990s, the increasing software size meant large packages like Windows or Adobe Photoshop required a dozen disks or more. In 1996, there were an estimated five billion standard floppy disks in use. Distribution of larger packages was replaced by CD-ROMs, DVDs and online distribution. An
Phosphor bronze is an alloy of copper with 0.5–11% of tin and 0.01–0.35% phosphorus. The tin increases the corrosion strength of the alloy; the phosphorus increases stiffness of the alloy. These alloys are notable for their toughness, low coefficient of friction, fine grain; the phosphorus reduces the viscosity of the molten alloy, which makes it easier and cleaner to cast and reduces grain boundaries between crystallites. Phosphor bronze is used for springs and various other items used in situations where resistance to fatigue and chemical corrosion are required; the alloy is used in some dental bridges. Grades A, C, E – C51000, C52100, C50700 are used nonferrous spring alloys; the combination of good physical properties, fair electrical conductivity, moderate cost make phosphor bronze round, square and special-shaped wire desirable for many springs, electrical contacts, a wide variety of wire forms where the desired properties do not require the use of more expensive beryllium copper. Phosphor bronze is used in cryogenics.
In this application, its combination of fair electrical conductivity and low thermal conductivity allows the making of electrical connections to devices at ultra low temperatures without adding excessive heat. Oxygen-free copper can be alloyed with phosphorus to better withstand oxidizing conditions; this alloy has application as thick corrosion-resistant overpack for spent nuclear fuel disposal in deep crystalline rocks. Magnetic tape was first used to record computer data in 1951 on the Eckert-Mauchly UNIVAC I; the UNISERVO drive recording medium was a thin metal strip of 0.5-inch wide nickel-plated phosphor bronze. Recording density was 128 characters per inch on eight tracks at a linear speed of 100 in/s, yielding a data rate of 12,800 characters per second. Of the eight tracks, six were data, one was a parity track, one was a clock, or timing track. Making allowance for the empty space between tape blocks, the actual transfer rate was around 7,200 characters per second. A small reel of mylar tape provided separation from the read/write head.
Phosphor bronze is preferred over brass for cymbals because of its greater resilience, leading to broader tonal spectrum and greater sustain. Phosphor bronze is one of several high copper content alloys used as a substitute for the more common "yellow" or "cartridge" types of brass to construct the bodies and bells of metal wind instruments. Examples of instruments constructed using high copper alloys occur among members of the brass instrument family and one member of the reed instrument family, saxophones. In addition to the distinctive appearance provided by the reddish-orange hue of high copper alloys, they are purported by some instrument designers and players to provide a broader harmonic response spectrum for a given instrument design; the Yanagisawa 902/992 model saxophones have bodies of phosphor bronze, in contrast to the brass 901/991 models. Some instrument strings for acoustic guitars and violins are wrapped with phosphor bronze; some harmonica reeds are made of phosphor bronze, such as those by Buckeye Music and the Suzuki Musical Instrument Corporation.
Some snare drums are constructed with phosphor bronze. Further increasing the phosphorus content leads to formation of a hard compound Cu3P, resulting in a brittle form of phosphor bronze, which has a narrow range of applications. Around 2001, the Olin Corporation developed another alloy for use in electrical and electronic connectors which they referred to as "phosphor bronze", its composition was as follows: Zinc – 9.9% Tin – 2.2% Iron – 1.9% Phosphorus – 0.03% Copper – 85.97%When assessed in metallurgical terms it is not a phosphor bronze, but a form of iron-modified tin brass. Copper and copper alloy microstructures: Phosphor bronze Phosphor Bronze: Teaching an Old Dog New Tricks National Pollutant Inventory - Copper and compounds fact sheet