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68-504: Natantia (Boas, 1880) is an obsolete taxon of decapod crustaceans , comprising those families that move predominantly by swimming – the shrimp (comprising Caridea and Procarididea ), prawns ( Dendrobranchiata ) and boxer shrimp . The remaining Decapoda were placed in the Reptantia , and consisted of crabs , lobsters and other large animals that move chiefly by walking along the bottom. The division between Natantia and Reptantia

136-492: A design flow that engineers use to design, verify, and analyze entire semiconductor chips. Some of the latest EDA tools use artificial intelligence (AI) to help engineers save time and improve chip performance. Integrated circuits can be broadly classified into analog , digital and mixed signal , consisting of analog and digital signaling on the same IC. Digital integrated circuits can contain billions of logic gates , flip-flops , multiplexers , and other circuits in

204-627: A fabrication facility (commonly known as a semiconductor fab ) can cost over US$ 12 billion to construct. The cost of a fabrication facility rises over time because of increased complexity of new products; this is known as Rock's law . Such a facility features: ICs can be manufactured either in-house by integrated device manufacturers (IDMs) or using the foundry model . IDMs are vertically integrated companies (like Intel and Samsung ) that design, manufacture and sell their own ICs, and may offer design and/or manufacturing (foundry) services to other companies (the latter often to fabless companies ). In

272-412: A microprocessor will have memory on the chip. (See the regular array structure at the bottom of the first image. ) Although the structures are intricate – with widths which have been shrinking for decades – the layers remain much thinner than the device widths. The layers of material are fabricated much like a photographic process, although light waves in the visible spectrum cannot be used to "expose"

340-466: A common active area, but there was no electrical isolation to separate them from each other. The monolithic integrated circuit chip was enabled by the inventions of the planar process by Jean Hoerni and p–n junction isolation by Kurt Lehovec . Hoerni's invention was built on Carl Frosch and Lincoln Derick's work on surface protection and passivation by silicon dioxide masking and predeposition, as well as Fuller, Ditzenberger's and others work on

408-561: A common substrate in a three-stage amplifier arrangement. Jacobi disclosed small and cheap hearing aids as typical industrial applications of his patent. An immediate commercial use of his patent has not been reported. Another early proponent of the concept was Geoffrey Dummer (1909–2002), a radar scientist working for the Royal Radar Establishment of the British Ministry of Defence . Dummer presented

476-491: A few square millimeters. The small size of these circuits allows high speed, low power dissipation, and reduced manufacturing cost compared with board-level integration. These digital ICs, typically microprocessors , DSPs , and microcontrollers , use boolean algebra to process "one" and "zero" signals . Among the most advanced integrated circuits are the microprocessors or " cores ", used in personal computers, cell-phones, etc. Several cores may be integrated together in

544-428: A large transistor count . The IC's mass production capability, reliability, and building-block approach to integrated circuit design have ensured the rapid adoption of standardized ICs in place of designs using discrete transistors. ICs are now used in virtually all electronic equipment and have revolutionized the world of electronics . Computers, mobile phones, and other home appliances are now essential parts of

612-408: A layer of material, as they would be too large for the features. Thus photons of higher frequencies (typically ultraviolet ) are used to create the patterns for each layer. Because each feature is so small, electron microscopes are essential tools for a process engineer who might be debugging a fabrication process. Each device is tested before packaging using automated test equipment (ATE), in

680-411: A new product or technology supersedes the old one, and it is preferred to use the new technology instead. Historical examples of new technologies superseding old ones include bronze replacing flint in hand-tools, DVDs replacing videocassettes , and the telephone replacing the telegraph . On a smaller scale, a particular product may become obsolete when a newer version replaces it. Many products in

748-428: A number of steps for the p–n junction isolation of transistors on a chip, MOSFETs required no such steps but could be easily isolated from each other. Its advantage for integrated circuits was pointed out by Dawon Kahng in 1961. The list of IEEE milestones includes the first integrated circuit by Kilby in 1958, Hoerni's planar process and Noyce's planar IC in 1959. The earliest experimental MOS IC to be fabricated

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816-420: A process known as wafer testing , or wafer probing. The wafer is then cut into rectangular blocks, each of which is called a die . Each good die (plural dice , dies , or die ) is then connected into a package using aluminium (or gold) bond wires which are thermosonically bonded to pads , usually found around the edge of the die. Thermosonic bonding was first introduced by A. Coucoulas which provided

884-624: A product. For example, many integrated circuits , including CPUs, memory and even some relatively simple logic chips may no longer be produced because the technology has been superseded, their original developer has gone out of business or a competitor has bought them out and effectively killed off their products to remove competition. It is rarely worth redeveloping a product to get around these issues since its overall functionality and price/performance ratio has usually been superseded by that time as well. Some products become technologically obsolete due to changes in complementary products which results in

952-421: A rate predicted by Moore's law , leading to large-scale integration (LSI) with hundreds of transistors on a single MOS chip by the late 1960s. Following the development of the self-aligned gate (silicon-gate) MOSFET by Robert Kerwin, Donald Klein and John Sarace at Bell Labs in 1967, the first silicon-gate MOS IC technology with self-aligned gates , the basis of all modern CMOS integrated circuits,

1020-407: A reliable means of forming these vital electrical connections to the outside world. After packaging, the devices go through final testing on the same or similar ATE used during wafer probing. Industrial CT scanning can also be used. Test cost can account for over 25% of the cost of fabrication on lower-cost products, but can be negligible on low-yielding, larger, or higher-cost devices. As of 2022 ,

1088-426: A semiconductor to modulate its electronic properties. Doping is the process of adding dopants to a semiconductor material. Since a CMOS device only draws current on the transition between logic states , CMOS devices consume much less current than bipolar junction transistor devices. A random-access memory is the most regular type of integrated circuit; the highest density devices are thus memories; but even

1156-569: A shrinking user base becomes unprofitable. This causes scarcity of spare parts and skilled technicians for repairs and thus escalates maintenance costs for obsolete products. This ultimately leads to prohibitive expense in keeping old technology functioning. The term "obsolescence" was first applied to the built environment in 1910 in an attempt to explain American skyscrapers' sudden loss of value. New York engineer Reginald P. Bolton attributed this phenomenon to "something new and better out-competing

1224-859: A single IC or chip. Digital memory chips and application-specific integrated circuits (ASICs) are examples of other families of integrated circuits. In the 1980s, programmable logic devices were developed. These devices contain circuits whose logical function and connectivity can be programmed by the user, rather than being fixed by the integrated circuit manufacturer. This allows a chip to be programmed to do various LSI-type functions such as logic gates , adders and registers . Programmability comes in various forms – devices that can be programmed only once , devices that can be erased and then re-programmed using UV light , devices that can be (re)programmed using flash memory , and field-programmable gate arrays (FPGAs) which can be programmed at any time, including during operation. Current FPGAs can (as of 2016) implement

1292-532: A single die. A technique has been demonstrated to include microfluidic cooling on integrated circuits, to improve cooling performance as well as peltier thermoelectric coolers on solder bumps, or thermal solder bumps used exclusively for heat dissipation, used in flip-chip . The cost of designing and developing a complex integrated circuit is quite high, normally in the multiple tens of millions of dollars. Therefore, it only makes economic sense to produce integrated circuit products with high production volume, so

1360-495: A single layer on one side of a chip of silicon in a flat two-dimensional planar process . Researchers have produced prototypes of several promising alternatives, such as: As it becomes more difficult to manufacture ever smaller transistors, companies are using multi-chip modules / chiplets , three-dimensional integrated circuits , package on package , High Bandwidth Memory and through-silicon vias with die stacking to increase performance and reduce size, without having to reduce

1428-486: A six-pin device. Radios with the Loewe 3NF were less expensive than other radios, showing one of the advantages of integration over using discrete components , that would be seen decades later with ICs. Early concepts of an integrated circuit go back to 1949, when German engineer Werner Jacobi ( Siemens AG ) filed a patent for an integrated-circuit-like semiconductor amplifying device showing five transistors on

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1496-512: A small piece of semiconductor material, usually silicon . Integrated circuits are used in a wide range of electronic devices, including computers , smartphones , and televisions , to perform various functions such as processing and storing information. They have greatly impacted the field of electronics by enabling device miniaturization and enhanced functionality. Integrated circuits are orders of magnitude smaller, faster, and less expensive than those constructed of discrete components, allowing

1564-505: A year after Kilby, Robert Noyce at Fairchild Semiconductor invented the first true monolithic IC chip. More practical than Kilby's implementation, Noyce's chip was made of silicon , whereas Kilby's was made of germanium , and Noyce's was fabricated using the planar process , developed in early 1959 by his colleague Jean Hoerni and included the critical on-chip aluminum interconnecting lines. Modern IC chips are based on Noyce's monolithic IC, rather than Kilby's. NASA's Apollo Program

1632-477: Is defined as to the activities that are undertaken to mitigate the effects of obsolescence. Activities can include last-time buys, lifetime buys, and obsolescence monitoring. Integrated circuit An integrated circuit ( IC ), also known as a microchip , computer chip , or simply chip , is a small electronic device made up of multiple interconnected electronic components such as transistors , resistors , and capacitors . These components are etched onto

1700-408: Is facing issues where life cycles of products no longer fit together with life cycles of required components. This issue is known as obsolescence, the status given to a part when it is no longer available from its original manufacturer. The problem of obsolescence is most prevalent for electronics technology, wherein the procurement lifetimes for microelectronic parts are often significantly shorter than

1768-447: Is low because the chips, with all their components, are printed as a unit by photolithography rather than being constructed one transistor at a time. Furthermore, packaged ICs use much less material than discrete circuits. Performance is high because the IC's components switch quickly and consume comparatively little power because of their small size and proximity. The main disadvantage of ICs

1836-489: Is no longer desirable because style trends have moved away from the flared leg cut. Because of the "fashion cycle", stylistically obsolete products may eventually regain popularity and cease to be obsolete. An example is " acid-wash " jeans, which were popular in the 1980s, became stylistically obsolete in the mid to late 1990s, and returned to popularity in the 2000s. Obsolescence management, also referred to as "Diminishing Manufacturing Sources and Material Shortages" (DMSMS),

1904-690: Is obsolete. An early attempt at combining several components in one device (like modern ICs) was the Loewe 3NF vacuum tube first made in 1926. Unlike ICs, it was designed with the purpose of tax avoidance , as in Germany, radio receivers had a tax that was levied depending on how many tube holders a radio receiver had. It allowed radio receivers to have a single tube holder. One million were manufactured, and were "a first step in integration of radioelectronic devices". The device contained an amplifier , composed of three triodes, two capacitors and four resistors in

1972-413: Is the high initial cost of designing them and the enormous capital cost of factory construction. This high initial cost means ICs are only commercially viable when high production volumes are anticipated. An integrated circuit is defined as: A circuit in which all or some of the circuit elements are inseparably associated and electrically interconnected so that it is considered to be indivisible for

2040-476: The dual in-line package (DIP), first in ceramic and later in plastic, which is commonly cresol - formaldehyde - novolac . In the 1980s pin counts of VLSI circuits exceeded the practical limit for DIP packaging, leading to pin grid array (PGA) and leadless chip carrier (LCC) packages. Surface mount packaging appeared in the early 1980s and became popular in the late 1980s, using finer lead pitch with leads formed as either gull-wing or J-lead, as exemplified by

2108-488: The non-recurring engineering (NRE) costs are spread across typically millions of production units. Modern semiconductor chips have billions of components, and are far too complex to be designed by hand. Software tools to help the designer are essential. Electronic design automation (EDA), also referred to as electronic computer-aided design (ECAD), is a category of software tools for designing electronic systems , including integrated circuits. The tools work together in

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2176-498: The periodic table of the chemical elements were identified as the most likely materials for a solid-state vacuum tube . Starting with copper oxide , proceeding to germanium , then silicon , the materials were systematically studied in the 1940s and 1950s. Today, monocrystalline silicon is the main substrate used for ICs although some III-V compounds of the periodic table such as gallium arsenide are used for specialized applications like LEDs , lasers , solar cells and

2244-544: The small-outline integrated circuit (SOIC) package – a carrier which occupies an area about 30–50% less than an equivalent DIP and is typically 70% thinner. This package has "gull wing" leads protruding from the two long sides and a lead spacing of 0.050 inches. In the late 1990s, plastic quad flat pack (PQFP) and thin small-outline package (TSOP) packages became the most common for high pin count devices, though PGA packages are still used for high-end microprocessors . Ball grid array (BGA) packages have existed since

2312-416: The switching power consumption per transistor goes down, while the memory capacity and speed go up, through the relationships defined by Dennard scaling ( MOSFET scaling ). Because speed, capacity, and power consumption gains are apparent to the end user, there is fierce competition among the manufacturers to use finer geometries. Over the years, transistor sizes have decreased from tens of microns in

2380-503: The very large-scale integration (VLSI) of more than 10,000 transistors on a single chip. At first, MOS-based computers only made sense when high density was required, such as aerospace and pocket calculators . Computers built entirely from TTL, such as the 1970 Datapoint 2200 , were much faster and more powerful than single-chip MOS microprocessors such as the 1972 Intel 8008 until the early 1980s. Advances in IC technology, primarily smaller features and larger chips, have allowed

2448-425: The 1970s. Flip-chip Ball Grid Array packages, which allow for a much higher pin count than other package types, were developed in the 1990s. In an FCBGA package, the die is mounted upside-down (flipped) and connects to the package balls via a package substrate that is similar to a printed-circuit board rather than by wires. FCBGA packages allow an array of input-output signals (called Area-I/O) to be distributed over

2516-482: The 22 nm node (Intel) or 16/14 nm nodes. Mono-crystal silicon wafers are used in most applications (or for special applications, other semiconductors such as gallium arsenide are used). The wafer need not be entirely silicon. Photolithography is used to mark different areas of the substrate to be doped or to have polysilicon, insulators or metal (typically aluminium or copper) tracks deposited on them. Dopants are impurities intentionally introduced to

2584-479: The components of the electronic circuit are completely integrated". The first customer for the new invention was the US Air Force . Kilby won the 2000 Nobel Prize in physics for his part in the invention of the integrated circuit. However, Kilby's invention was not a true monolithic integrated circuit chip since it had external gold-wire connections, which would have made it difficult to mass-produce. Half

2652-403: The computer industry become obsolete in this manner. For example, central processing units (CPUs) frequently become obsolete in favor of newer, faster units. Singularly, rapid obsolescence of data formats along with their supporting hardware and software can lead to loss of critical information, a process known as digital obsolescence . In many cases, a new technology does not totally replace

2720-473: The desktop Datapoint 2200 were built from bipolar integrated circuits, either TTL or the even faster emitter-coupled logic (ECL). Nearly all modern IC chips are metal–oxide–semiconductor (MOS) integrated circuits, built from MOSFETs (metal–oxide–silicon field-effect transistors). The MOSFET invented at Bell Labs between 1955 and 1960, made it possible to build high-density integrated circuits . In contrast to bipolar transistors which required

2788-418: The die must pass through the material electrically connecting the die to the package, through the conductive traces (paths) in the package, through the leads connecting the package to the conductive traces on the printed circuit board . The materials and structures used in the path these electrical signals must travel have very different electrical properties, compared to those that travel to different parts of

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2856-541: The diffusion of impurities into silicon. A precursor idea to the IC was to create small ceramic substrates (so-called micromodules ), each containing a single miniaturized component. Components could then be integrated and wired into a bidimensional or tridimensional compact grid. This idea, which seemed very promising in 1957, was proposed to the US Army by Jack Kilby and led to the short-lived Micromodule Program (similar to 1951's Project Tinkertoy). However, as

2924-537: The early 1970s to 10 nanometers in 2017 with a corresponding million-fold increase in transistors per unit area. As of 2016, typical chip areas range from a few square millimeters to around 600 mm , with up to 25 million transistors per mm . The expected shrinking of feature sizes and the needed progress in related areas was forecast for many years by the International Technology Roadmap for Semiconductors (ITRS). The final ITRS

2992-541: The entire die rather than being confined to the die periphery. BGA devices have the advantage of not needing a dedicated socket but are much harder to replace in case of device failure. Intel transitioned away from PGA to land grid array (LGA) and BGA beginning in 2004, with the last PGA socket released in 2014 for mobile platforms. As of 2018 , AMD uses PGA packages on mainstream desktop processors, BGA packages on mobile processors, and high-end desktop and server microprocessors use LGA packages. Electrical signals leaving

3060-580: The equivalent of millions of gates and operate at frequencies up to 1 GHz . Analog ICs, such as sensors , power management circuits , and operational amplifiers (op-amps), process continuous signals , and perform analog functions such as amplification , active filtering , demodulation , and mixing . ICs can combine analog and digital circuits on a chip to create functions such as analog-to-digital converters and digital-to-analog converters . Such mixed-signal circuits offer smaller size and lower cost, but must account for signal interference. Prior to

3128-412: The foundry model, fabless companies (like Nvidia ) only design and sell ICs and outsource all manufacturing to pure play foundries such as TSMC . These foundries may offer IC design services. The earliest integrated circuits were packaged in ceramic flat packs , which continued to be used by the military for their reliability and small size for many years. Commercial circuit packaging quickly moved to

3196-709: The function of the first product being made unnecessary. For example, buggy whips became obsolete when people started to travel in cars rather than in horse-drawn buggies. Items become functionally obsolete when they can no longer adequately perform the function for which they were created. For example, while one could theoretically adapt an Avro Lancaster to deploy modern JDAM bombs, the situations in which it could actually succeed at doing so against modern air defenses would be so few that it would be essentially useless. Manufacturers and repair companies will typically cease support for products once they become obsolete as keeping production lines in place and parts in storage for

3264-568: The highest-speed integrated circuits. It took decades to perfect methods of creating crystals with minimal defects in semiconducting materials' crystal structure . Semiconductor ICs are fabricated in a planar process which includes three key process steps – photolithography , deposition (such as chemical vapor deposition ), and etching . The main process steps are supplemented by doping and cleaning. More recent or high-performance ICs may instead use multi-gate FinFET or GAAFET transistors instead of planar ones, starting at

3332-602: The idea to the public at the Symposium on Progress in Quality Electronic Components in Washington, D.C. , on 7 May 1952. He gave many symposia publicly to propagate his ideas and unsuccessfully attempted to build such a circuit in 1956. Between 1953 and 1957, Sidney Darlington and Yasuo Tarui ( Electrotechnical Laboratory ) proposed similar chip designs where several transistors could share

3400-421: The late 1990s, radios could not be fabricated in the same low-cost CMOS processes as microprocessors. But since 1998, radio chips have been developed using RF CMOS processes. Examples include Intel's DECT cordless phone, or 802.11 ( Wi-Fi ) chips created by Atheros and other companies. Modern electronic component distributors often further sub-categorize integrated circuits: The semiconductors of

3468-517: The manufacturing and support life cycles for the products that use the parts. However, obsolescence extends beyond electronic components to other items, such as materials, textiles, and mechanical parts. In addition, obsolescence has been shown to appear for software, specifications, standards, processes, and soft resources, such as human skills. It is highly important to implement and operate an active management of obsolescence to mitigate and avoid extreme costs. Technical obsolescence usually occurs when

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3536-433: The number of MOS transistors in an integrated circuit to double every two years, a trend known as Moore's law. Moore originally stated it would double every year, but he went on to change the claim to every two years in 1975. This increased capacity has been used to decrease cost and increase functionality. In general, as the feature size shrinks, almost every aspect of an IC's operation improves. The cost per transistor and

3604-562: The old technology because the old technology is still useful in certain applications. For example, transistors replaced vacuum tubes in TV and radio receivers in the 1960s, but vacuum tubes were still used for powerful transmitters because transistors for these power levels were not available. Even today, one has to use multiple transistors for a purpose that used to require just one tube. Products may also become obsolete when supporting technologies are no longer available to produce or even repair

3672-448: The old" and calculated the average architectural lifespan of varying building types in order to formulate a rough estimate for their impending obsolescence. For example, he suggested that hotels' obsolescence will occur faster than banks due to their ever-changing functions and tastes. Sometimes marketers deliberately introduce obsolescence into their product strategy , with the objective of generating long-term sales volume by reducing

3740-426: The original. Obsolete also refers to something that is already disused or discarded, or antiquated. Typically, obsolescence is preceded by a gradual decline in popularity. Driven by rapid technological changes , new components are developed and launched on the market with increasing speed. The result is a dramatic change in production methods of all components and their market availability. A growing industry sector

3808-497: The project was gaining momentum, Kilby came up with a new, revolutionary design: the IC. Newly employed by Texas Instruments , Kilby recorded his initial ideas concerning the integrated circuit in July 1958, successfully demonstrating the first working example of an integrated circuit on 12 September 1958. In his patent application of 6 February 1959, Kilby described his new device as "a body of semiconductor material … wherein all

3876-592: The purposes of construction and commerce. In strict usage, integrated circuit refers to the single-piece circuit construction originally known as a monolithic integrated circuit , which comprises a single piece of silicon. In general usage, circuits not meeting this strict definition are sometimes referred to as ICs, which are constructed using many different technologies, e.g. 3D IC , 2.5D IC , MCM , thin-film transistors , thick-film technologies , or hybrid integrated circuits . The choice of terminology frequently appears in discussions related to whether Moore's Law

3944-472: The risks of products becoming obsolete and have a detrimental effect on the organisation's cash flow . Companies may address this problem alongside a periodic stock count by assessing which of their stock items are slow-moving or not selling at all. When a product is no longer desirable because it has gone out of the popular fashion, its style is obsolete. One example is flared leg jeans ; although this article of clothing may still be perfectly functional, it

4012-449: The same size – a modern chip may have many billions of transistors in an area the size of a human fingernail. These advances, roughly following Moore's law , make the computer chips of today possess millions of times the capacity and thousands of times the speed of the computer chips of the early 1970s. ICs have three main advantages over circuits constructed out of discrete components: size, cost and performance. The size and cost

4080-474: The size of the transistors. Such techniques are collectively known as advanced packaging . Advanced packaging is mainly divided into 2.5D and 3D packaging. 2.5D describes approaches such as multi-chip modules while 3D describes approaches where dies are stacked in one way or another, such as package on package and high bandwidth memory. All approaches involve 2 or more dies in a single package. Alternatively, approaches such as 3D NAND stack multiple layers on

4148-445: The structure of modern societies, made possible by the small size and low cost of ICs such as modern computer processors and microcontrollers . Very-large-scale integration was made practical by technological advancements in semiconductor device fabrication . Since their origins in the 1960s, the size, speed, and capacity of chips have progressed enormously, driven by technical advances that fit more and more transistors on chips of

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4216-440: The time between repeat purchases. One example might be producing an appliance which is deliberately designed to wear out within five years of its purchase, pushing consumers to replace it within five years. Inventory obsolescence occurs when retailers and other vendors hold stocks for anticipated future sales which turn out to be too slow to materialise. Holding excessive levels of stock or over-predicting potential demand increase

4284-401: Was a 16-transistor chip built by Fred Heiman and Steven Hofstein at RCA in 1962. General Microelectronics later introduced the first commercial MOS integrated circuit in 1964, a 120-transistor shift register developed by Robert Norman. By 1964, MOS chips had reached higher transistor density and lower manufacturing costs than bipolar chips. MOS chips further increased in complexity at

4352-441: Was developed at Fairchild Semiconductor by Federico Faggin in 1968. The application of MOS LSI chips to computing was the basis for the first microprocessors , as engineers began recognizing that a complete computer processor could be contained on a single MOS LSI chip. This led to the inventions of the microprocessor and the microcontroller by the early 1970s. During the early 1970s, MOS integrated circuit technology enabled

4420-514: Was issued in 2016, and it is being replaced by the International Roadmap for Devices and Systems . Initially, ICs were strictly electronic devices. The success of ICs has led to the integration of other technologies, in an attempt to obtain the same advantages of small size and low cost. These technologies include mechanical devices, optics, and sensors. As of 2018 , the vast majority of all transistors are MOSFETs fabricated in

4488-461: Was replaced in 1963, when Martin Burkenroad erected the suborder Pleocyemata for those animals that brood their eggs on the pleopods , leaving Dendrobranchiata for the prawns. Under this system, Natantia is a paraphyletic group . Burkenroad's primary division of Decapoda into Dendrobranchiata and Pleocyemata has since been corroborated by molecular analyses . The name Natantia Owen, 1851

4556-480: Was the largest single consumer of integrated circuits between 1961 and 1965. Transistor–transistor logic (TTL) was developed by James L. Buie in the early 1960s at TRW Inc. TTL became the dominant integrated circuit technology during the 1970s to early 1980s. Dozens of TTL integrated circuits were a standard method of construction for the processors of minicomputers and mainframe computers . Computers such as IBM 360 mainframes, PDP-11 minicomputers and

4624-442: Was utilized in a phylogenetic context by Madzia and Cau (2017) as the most exclusive mosasaurid clade including Mosasaurus and Tylosaurus but not Halisaurus . This Decapoda article is a stub . You can help Misplaced Pages by expanding it . Obsolete Obsolescence frequently occurs because a replacement has become available that has, in sum, more advantages compared to the disadvantages incurred by maintaining or repairing

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