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The Wildlife Trusts

The Wildlife Trusts, the trading name of the Royal Society of Wildlife Trusts, is an organisation made up of 46 local Wildlife Trusts in the United Kingdom, the Isle of Man and Alderney. The Wildlife Trusts, between them, look after more than 2,300 nature reserves, covering around 98500 ha. , the Trusts have a combined membership of over 870,000 members.

The Royal Society of Wildlife Trusts (RSWT) is an independent charity, with a membership formed of the 46 individual charitable Trusts. It acts as an umbrella group for the individual Wildlife Trusts, as well as operating a separate Grants Unit which administers a number of funds.

King Charles III serves as the patron of the Wildlife Trusts. David Bellamy was president of The Wildlife Trusts for ten years between 1995 and 2005, and was succeeded by Aubrey Manning. Sir David Attenborough, Simon King and Tony Juniper are all Presidents Emeritus. Stephanie Hilborne OBE was chief executive for 15 years, and left in October 2019. Craig Bennett became CEO from April 6, 2020.

Activities
Wildlife Trusts are local organisations of differing size, history and origins, and can vary greatly in their constitution, activities and membership. However, all Wildlife Trusts share a common interest in wildlife and biodiversity, rooted in a practical tradition of land management and conservation. Almost all Wildlife Trusts are significant landowners, with many nature reserves. Collectively they are the third largest voluntary sector landowners in the UK. They often have extensive educational activities, and programmes of public events and education. The Wildlife Trusts centrally and locally also lobby for better protection of the UK's natural heritage, by becoming involved in planning matters and by national campaigning through the Royal Society of Wildlife Trusts. The Trusts rely heavily upon volunteer labour for many of their activities, but nevertheless employ significant numbers of staff in countryside management and education. Thanks to their work promoting the personal and social development of young people, The Wildlife Trusts is a member of The National Council for Voluntary Youth Services (NCVYS).

The Wildlife Trusts offer a Biodiversity Benchmark scheme through which companies can be assessed and recognised for their contribution to biodiversity. The assessment covers the organisation's performance under the headings of "Commitment, Planning, Implementation, and Monitoring and Review".

The Wildlife Trusts are one of the steering group partners of Neighbourhoods Green, a partnership initiative which works with social landlords and housing associations to highlight the importance of, and raise the overall quality of design and management for, open and green space in social housing.

Kathryn Brown OBE was appointed as the charity’s first director of climate action in January 2022.

History

Today's Wildlife Trust movement began life as The Society for the Promotion of Nature Reserves (SPNR), which was formed by Charles Rothschild in 1912. It aimed initially to draw up a list of the country's best wildlife sites with a view to purchase for protection as nature reserves, and by 1915 it had drawn up a list of 284 (including the Farne Islands and the Norfolk Broads), known as Rothschild Reserves. During the early years, membership tended to be made up of specialist naturalists and its growth was comparatively slow. The first independent Trust was formed in Norfolk in 1926 as the Norfolk Naturalists Trust, followed in 1938 by the Pembrokeshire Bird Protection Society which after several subsequent changes of name is now the Wildlife Trust of South and West Wales and it was not until the 1940s and 1950s that more Naturalists' Trusts were formed in Yorkshire (1946), Lincolnshire (1948), Leicestershire (1956) and Cambridgeshire (1956). These early Trusts tended to focus on purchasing land to establish nature reserves in the geographical areas they served.

Encouraged by the growing number of Trusts, the SPNR began in 1957 to discuss the possibility of forming a national federation of Naturalists' Trusts. Kent Naturalists Trust was established in 1958 with SPNR being active in encouraging its formation. In the following year the SPNR established the County Naturalists' Committee, which organised the first national conference for Naturalists' Trusts at Skegness in 1960. By 1964, the number of Trusts had increased to 36 and the Society for the Promotion of Nature Reserves had changed its name to The Society for the Promotion of Nature Conservation. In recognition of the movement's growing importance, its name was changed to The Royal Society for Nature Conservation in 1981.

The movement continued to develop throughout the 1970s, and, by the early 1980s, most of today's Trusts had been established. In 1980, the first urban Wildlife Trust (now the Wildlife Trust for Birmingham and the Black Country) was established in the West Midlands, rapidly followed by others in London, Bristol and Sheffield. This was a watershed for the movement that strengthened its focus on wildlife and people. It was during this period that some Trusts changed their names from Naturalist Societies to Trusts for Nature Conservation. In 2002 the group changed their name to The Royal Society of Wildlife Trusts. The badger logo was adopted by the movement to establish its common identity. Also in 2002, the newest wildlife trust was formed, in Alderney.

As the number of Trusts grew, so did their combined membership, from 3,000 in 1960 to 21,000 in 1965. Membership topped 100,000 in 1975, and in that year Wildlife Watch was launched as a children's naturalist club. By the late 1980s membership had reached 200,000, increasing to 260,000 in 1995, and over 500,000 by 2004. The combined membership for 2007 stood at 670,000 members, 108,000 belonging to the junior branch Wildlife Watch.

By 2012, membership was over 800,000, with over 150,000 Wildlife Watch members.

List of Wildlife Trusts

 * Alderney Wildlife Trust
 * Avon Wildlife Trust
 * Berkshire, Buckinghamshire and Oxfordshire Wildlife Trust
 * Cheshire Wildlife Trust
 * Cornwall Wildlife Trust
 * Cumbria Wildlife Trust
 * Derbyshire Wildlife Trust
 * Devon Wildlife Trust
 * Dorset Wildlife Trust
 * Durham Wildlife Trust
 * Essex Wildlife Trust
 * Gloucestershire Wildlife Trust
 * Gwent Wildlife Trust, Wales
 * Hampshire and Isle of Wight Wildlife Trust
 * Herefordshire Wildlife Trust
 * Herts and Middlesex Wildlife Trust
 * Isles of Scilly Wildlife Trust
 * Kent Wildlife Trust
 * Leicestershire and Rutland Wildlife Trust
 * Lincolnshire Wildlife Trust
 * London Wildlife Trust
 * Manx Wildlife Trust / Treisht Bea-Feie Vannin
 * Montgomeryshire Wildlife Trust
 * Norfolk Wildlife Trust
 * North Wales Wildlife Trust
 * Northumberland Wildlife Trust
 * Nottinghamshire Wildlife Trust
 * Radnorshire Wildlife Trust
 * Scottish Wildlife Trust
 * Sheffield & Rotherham Wildlife Trust
 * Shropshire Wildlife Trust
 * Somerset Wildlife Trust
 * Staffordshire Wildlife Trust
 * Suffolk Wildlife Trust
 * Surrey Wildlife Trust
 * Sussex Wildlife Trust
 * Tees Valley Wildlife Trust
 * Wildlife Trust for Bedfordshire, Cambridgeshire and Northamptonshire
 * Wildlife Trust for Birmingham and the Black Country
 * Wildlife Trust for Lancashire, Manchester and North Merseyside
 * Wildlife Trust of South and West Wales
 * Ulster Wildlife Trust
 * Warwickshire Wildlife Trust
 * Wiltshire Wildlife Trust
 * Worcestershire Wildlife Trust
 * Yorkshire Wildlife Trust

title: The Wildlife Trusts


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Gaur

The gaur (Bos gaurus; ) is a bovine native to South Asia and Southeast Asia, and has been listed as Vulnerable on the IUCN Red List since 1986. The global population was estimated at a maximum of 21,000 mature individuals in 2016, with the majority of those existing in India.

It is the largest species among the wild cattle and the Bovidae. The domesticated form of the gaur is called gayal (Bos frontalis) or mithun.

Etymology
The Sanskrit word गौर means 'white, yellowish, reddish'. The Sanskrit word means a kind of water buffalo.

The Hindi word गौर means 'fair-skinned, fair, white'.

Taxonomy
Bison gaurus was the scientific name proposed by Charles Hamilton Smith in 1827. Later authors subordinated the species under either Bos or Bibos.

To date, three gaur subspecies have been recognized:
 * B. g. gaurus; the nominate subspecies, ranges in India, Nepal and Bhutan.
 * B. g. readei; described by Richard Lydekker in 1903, based on a specimen from Myanmar, and is thought to range from Upper Myanmar to Tanintharyi Region.
 * B. g. hubbacki; described by Lydekker in 1907, based on a specimen from Pahang in Peninsular Malaysia. It was thought to range from Peninsular Malaysia and northward through Tenasserim. This classification, based largely on differences in coloration and size, is no longer widely recognized.

In 2003, the International Commission on Zoological Nomenclature fixed the valid specific name of the wild gaur as the first available name based on the wild population, despite being antedated by the name for the domestic form. Most authors have adopted the binomial Bos gaurus for the wild species as valid for the taxon.

In recognition of phenotypic differences between zoological specimens of Indian and Southeast Asian gaur, the trinomials Bos gaurus gaurus and Bos gaurus laosiensis are provisionally accepted, pending further morphometric and genetic study.

Within the genus Bos, the gaur is most closely related to the banteng (Bos javanicus) and the probably now extinct kouprey (Bos sauveli), which are also native to Southeast Asia. Relationships of members of the genus Bos based on nuclear genomes after Sinding, et al. 2021.

Characteristics
The gaur is the largest extant bovid. It is a strong and massively built bovine with a high convex ridge on the forehead between the horns, which protrudes anteriorly, causing a deep hollow in the profile of the upper part of the head. There is a prominent ridge on the back. The ears are very large. In the old bulls, the hair becomes very thin on the back. The adult male is dark brown, approaching black in very old individuals. The upper part of the head, from above the eyes to the nape of the neck, is ashy grey, or occasionally dirty white. The muzzle is pale coloured, and the lower part of the legs are pure white or tan. The cows and young bulls are paler, and in some instances have a rufous tinge, which is most marked in groups inhabiting dry and open areas. The tail is shorter than in the typical oxen, reaching only to the hocks. They have a distinct ridge running from the shoulders to the middle of the back; the shoulders may be as much as 12 cm higher than the rump. This ridge is caused by the great length of the spinous processes of the vertebrae of the fore-part of the trunk as compared with those of the loins. The hair is short, fine and glossy; the hooves are narrow and pointed.

The gaur has a distinct dewlap on the throat and chest. Both sexes have horns, which grow from the sides of the head, curving upwards. Between the horns is a high convex ridge on the forehead. At their bases they present an elliptical cross-section, a characteristic that is more strongly marked in bulls than in cows. The horns are decidedly flattened at the base and regularly curved throughout their length, and are bent inward and slightly backward at their tips. The colour of the horns is some shade of pale green or yellow throughout the greater part of their length, but the tips are black. The horns, of medium size by large bovid standards, grow to a length of 60 to 115 cm. The cow is considerably lighter in colour than the bull. Her horns are more slender and upright, with more inward curvature, and the frontal ridge is scarcely perceptible. In young animals, the horns are smooth and polished. In old bulls they are rugged and dented at the base.

The gaur has a head-and-body length of 250 to 330 cm with a 70 to 105 cm long tail, and is 142 to 220 cm high at the shoulder, averaging about 168 cm in females and 188 cm in males. At the top of its muscular hump just behind its shoulder, an average adult male is just under 200 cm tall and the male's girth at its midsection (behind its shoulders) averages about 277 cm. Males are about one-fourth larger and heavier than females. Body mass ranges widely from 440 to 1000 kg in adult females and 588 to 1500 kg in adult males. In general, measurements are derived from gaurs surveyed in India. In a sample of 13 individuals in India, gaur males averaged about 1500 kg and females weighed a median of approximately 700 kg. In China, the shoulder height of gaurs ranges from 165 to 220 cm, and bulls weigh up to 1500 kg.

Distribution and habitat
The gaur historically occurred throughout mainland South and Southeast Asia, including Nepal, India, Bhutan, Bangladesh, Myanmar, Thailand, Laos, Cambodia, Vietnam and China. Today, its range is seriously fragmented, and it is regionally extinct in Peninsular Malaysia and Sri Lanka. It is largely confined to evergreen forests or semi-evergreen and moist deciduous forests, but also inhabits deciduous forest areas at the periphery. Gaur habitat is characterized by large, relatively undisturbed forest tracts, hilly terrain below an elevation of 1500 to 1800 m, availability of water, and an abundance of forage in the form of grasses, bamboo, shrubs, and trees. Its apparent preference for hilly terrain may be partly due to the earlier conversion of most of the plains and other low-lying areas to croplands and pastures. It occurs from sea level to an elevation of at least 2800 m. Low-lying areas seem to comprise optimal habitat.

In Nepal, the gaur population was estimated to be 250–350 in the mid-1990s, with the majority in Chitwan National Park and the adjacent Parsa National Park. These two parks are connected by a chain of forested hills. Population trends appeared to be relatively stable. The Chitwan population has increased from 188 to 368 animals in the years 1997 to 2016. Census conducted in Parsa National Park confirmed the presence of 112 gaur in the same period.

In India, the population was estimated to be 12,000–22,000 in the mid-1990s. The Western Ghats and their outflanking hills in southern India constitute one of the most extensive extant strongholds of gaur, in particular in the Wayanad – Nagarhole – Mudumalai – Bandipur complex. The populations in India, Bhutan and Bangladesh are estimated to comprise 23,000–34,000 individuals. Major populations of about 2,000 individuals have been reported in both Nagarahole and Bandipur National Parks, over 1,000 individuals in Tadoba Andhari Tiger Project, 500–1000 individuals in both Periyar Tiger Reserve and Silent Valley and adjoining forest complexes, and over 800 individuals in Bhadra Wildlife Sanctuary. Trishna Wildlife Sanctuary in southern Tripura is home to a significant number of individuals.

In Bhutan, they apparently persist all over the southern foothill zone, notably in Royal Manas National Park, Phibsoo Wildlife Sanctuary and Khaling Wildlife Sanctuary.

In Bangladesh, a few gaur occur in the Chittagong Hill Tracts, mostly in Banderban district. During a camera trap project, few gaur were recorded indicating that the population is fragmented and probably declining. Gaurs are hunted by local tribal people in Sangu Matamuhari reserve forest although hunting is prohibited in Bangladesh.

In Thailand, gaur were once found throughout the country, but fewer than 1,000 individuals were estimated to have remained in the 1990s. In the mostly semi-evergreen Dong Phayayen – Khao Yai Forest Complex, they were recorded at low density at the turn of the century, with an estimated total of about 150 individuals.

In Vietnam, several areas in Đắk Lắk Province were known to contain gaur in 1997. Several herds persist in Cát Tiên National Park and in adjacent state forest enterprises. The current status of the gaur population is poorly known; they may be in serious decline.

In Cambodia, gaur declined considerably in the period from the late 1960s to the early 1990s. The most substantial population of the country remained in Mondulkiri Province, where up to 1000 individuals may have survived up to 2010 in a forested landscape of over 15000 km2. Results of camera trapping carried out in 2009 suggested a globally significant population of gaur in Sre Pok Wildlife Sanctuary and the contiguous Phnom Prich Wildlife Sanctuary, and line transect distance sampling from Keo Seima Wildlife Sanctuary showed around 500 individuals in 2010. Since then, there has been rapid decline of these populations, and likely all populations across Cambodia. Updated figures for Keo Seima Wildlife Sanctuary show a decline to only 33 individuals in 2020, and 2020 encounter rates in Sre Pok Wildlife Sanctuary and Phnom Prich Wildlife Sanctuary were too low to analyze with distance sampling.

In Laos, up to 200 individuals were estimated to inhabit protected area boundaries in the mid-1990s. They were reported discontinuously distributed in low numbers. Overhunting had reduced the population, and survivors occurred mainly in remote sites. Fewer than six National Biodiversity Conservation Areas held more than 50 individuals. Areas with populations likely to be nationally important included the Nam Theun catchment and the adjoining plateau. Subsequent surveys carried out a decade later using fairly intensive camera trapping did not record any gaur any more, indicating a massive decline of the population.

In China, the gaur was present up to the 34th parallel north during the late Neolithic period about 5,200 years BP. Now it occurs only in heavily fragmented populations in Yunnan and southeastern Tibet. By the 1980s, it was extirpated in Lancang County, and the remaining animals were split into two populations in Xishuangbanna–Simao District and Cangyuan. In the mid-1990s, a population of 600–800 individuals may have lived in Yunnan Province, with the majority occurring in Xishuangbanna National Nature Reserve.

In 2016, it was estimated that the population has declined by more than 70% in Indochina and Malaysia during the last three generations (generation length estimated at 8–10 years), and is extirpated from Sri Lanka. Populations in well-protected areas appeared to be stable.

Ecology and behaviour
Where gaur have not been disturbed, they are basically diurnal. In other areas, they have become largely nocturnal due to human impact on the forest. In central India, they are most active at night, and are rarely seen in the open after 8 o'clock in the morning. During the dry season, herds congregate and remain in small areas, dispersing into the hills with the arrival of the monsoon. While gaur depend on water for drinking, they do not seem to bathe or wallow.

In January and February, gaur live in small herds of eight to 11 individuals, one of which is a bull. In April or May, more bulls may join the herd for mating, and individual bulls may move from herd to herd, each mating with many cows. In May or June, they leave the herd and may form herds of bulls only or live alone. Herds wander 2 - 5 km each day. Each herd has a nonexclusive home range, and sometimes herds may join in groups of 50 or more.

Gaur herds are led by an old adult female, the matriarch. Adult males may be solitary. During the peak of the breeding season, unattached males wander widely in search of receptive females. No serious fighting between males has been recorded, with size being the major factor in determining dominance. Males make a mating call of clear, resonant tones which may carry for more than 1.6 km. Gaur have also been known to make a whistling snort as an alarm call, and a low, cow-like moo.

In some regions in India where human disturbance is minor, the gaur is very timid and shy despite their great size and power. When alarmed, gaur crash into the jungle at a surprising speed. However, in Southeast Asia and South India, where they are used to the presence of humans, gaur are said by locals to be very bold and aggressive. They are frequently known to go into fields and graze alongside domestic cattle, sometimes killing them in fights. Gaur bulls may charge without provocation, especially during summer, when the intense heat and parasitic insects make them more short-tempered than usual. To warn other members of its herd of approaching danger, the gaur lets out a high whistle for help.

Feeding ecology
The gaur grazes and browses mostly the upper portions of plants, such as leaf blades, stems, seeds and flowers of grass species, including kadam Adina cordifolia. During a survey in the Bhagwan Mahaveer Sanctuary and Mollem National Park, gaurs were observed to feed on 32 species of plants. They consume herbs, young shoots, flowers, fruits of elephant apple (Dillenia) with a high preference for leaves. Food preference varies by season. In winter and monsoon, they feed on preferably fine and fresh true grasses and herb species of the legume family, such as tick clover (Desmodium triflorum), but also browse on leaves of shrub species such as karvy (Strobilanthes callosus), Indian boxwood (Gardenia latifolia), mallow-leaved crossberry (Grewia abutifolia), East-Indian screw tree (Helicteres) and the chaste tree (Vitex negundo). In summer, they also feed on bark of teak (Tectona grandis), on fruit of golden shower tree (Cassia fistula), and on the bark and fruit of cashew (Anacardium occidentale). Gaur spent most of their daily time feeding. Peak feeding activity was observed between 6:30 and 8:30 in the mornings and between 17:30 and 18:45 in the evenings. During the hottest hours of the day, they rest in the shade of big trees.

They may debark trees due to shortages of preferred food, and of minerals and trace elements needed for their nutrition, or for maintaining an optimum fiber/protein ratio for proper digestion of food and better assimilation of nutrients. They may turn to available browse species and fibrous teak bark in summer as green grass and herbaceous resources dry up. High concentrations of calcium (22400 ppm) and phosphorus (400 ppm) have been reported in teak bark, so consumption of teak bark may help animals to satisfy both mineral and other food needs. Long-term survival and conservation of these herbivores depend on the availability of preferred plant species for food. Hence, protection of the historically preferred habitats used by gaur is a significant factor in conservation biology.

Reproduction
Sexual maturity occurs in the gaur's second or third year. Breeding takes place year-round, but typically peaks between December and June. Females have one calf, rarely two, after a gestation period of about 275 days, a few days less than domestic cattle. Calves are typically weaned after seven to 12 months. The lifespan of a gaur in captivity is up to 30 years.

Natural predators
Due to their size and power, gaur have few natural predators besides humans. Leopards, dhole packs and large mugger crocodiles occasionally attack unguarded calves or unhealthy animals. Only tigers and saltwater crocodiles have been reported to kill adult gaur. However, the habitat and distribution of the gaur and saltwater crocodile seldom overlap in recent times, due to the decreasing range of both species. A crocodile likely would need to be a mature adult male (more than 3.7 m and 300 kg) to make a successful attack on healthy adult gaurs.

Tigers hunt young or infirm gaur, but have also been reported to have killed healthy bulls weighing at least 1000 kg. When confronted by a tiger, the adult members of a gaur herd often form a circle surrounding the vulnerable young and calves, shielding them from the big cat. As tigers rely on ambush attacks when taking on prey as large as a gaur, they will almost always abandon a hunt if detected and met in this manner. A herd of gaur in Malaysia encircled a calf killed by a tiger and prevented it from approaching the carcass. Nevertheless, the gaur are formidable opponents to the tigers, and they are capable of killing tigers in self-defence.

Threats
In Laos, the gaur is highly threatened by poaching for trade to supply international markets, but also by opportunistic hunting, and specific hunting for home consumption. In the 1990s, gaurs were particularly sought by Vietnamese poachers for their commercial value. In Thailand, the gaur is severely threatened by poaching for commercial trade in meat and trophies.

Conservation
The gaur is listed in CITES Appendix I, and is legally protected in all range states.

In captivity
On 8 January 2001, the first cloned gaur was born at Trans Ova Genetics in Sioux Center, Iowa. The calf was carried and brought successfully to term by a surrogate mother, a domestic cow (Bos taurus). While healthy at birth, the calf died within 48 hours of a common dysentery, most likely unrelated to cloning.

In popular culture

 * The gaur is the mascot of the 54th Infantry Division of the Indian Army, which is also called the Bison Division.
 * The gaur is the state animal of Goa and Bihar. The Gaur is also the mascot of Goan football club FC Goa, competing in Indian Super League, where their team often referred as "The Gaurs".
 * The Red Gaurs (กระทิงแดง ) were an extreme right-wing paramilitary organization active in Thailand during the 1970s.
 * Krating Daeng today is a brand of energy drink featuring a pair of charging red gaur bulls in the logo; also used on the licensed derivative, "Red Bull".

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Gaur


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Talk:Heaven's Gate (disambiguation)

This needs to be distinguished from the Heaven's Gate suicide cult.

title: Talk:Heaven's Gate (disambiguation)


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ARCNET

Attached Resource Computer NETwork (ARCNET or ARCnet) is a communications protocol for local area networks. ARCNET was the first widely available networking system for microcomputers; it became popular in the 1980s for office automation tasks. It was later applied to embedded systems where certain features of the protocol are especially useful.

Development
ARCNET was developed by principal development engineer John Murphy at Datapoint Corporation in 1976 under Victor Poor, and announced in 1977. It was originally developed to connect groups of their Datapoint 2200 terminals to talk to a shared 8" floppy disk system. It was the first loosely coupled LAN-based clustering system, making no assumptions about the type of computers that would be connected. This was in contrast to contemporary larger and more expensive computer systems such as DECnet or SNA, where a homogeneous group of similar or proprietary computers were connected as a cluster.

The token-passing bus protocol of that I/O device-sharing network was subsequently applied to allowing processing nodes to communicate with each other for file-serving and computing scalability purposes. An application could be developed in DATABUS, Datapoint's proprietary COBOL-like language and deployed on a single computer with dumb terminals. When the number of users outgrew the capacity of the original computer, additional 'compute' resource computers could be attached via ARCNET, running the same applications and accessing the same data. If more storage was needed, additional disk resource computers could also be attached. This incremental approach broke new ground and by the end of the 1970s (before the first IBM PC was announced in 1981) over ten thousand ARCNET LAN installations were in commercial use around the world, and Datapoint had become a Fortune 500 company. As microcomputers took over the industry, well-proven and reliable ARCNET was also offered as an inexpensive LAN for these machines.

Market
ARCNET remained proprietary until the early-to-mid 1980s. This did not cause concern at the time, as most network architectures were proprietary. The move to non-proprietary, open systems began as a response to the dominance of International Business Machines (IBM) and its Systems Network Architecture (SNA). In 1979, the Open Systems Interconnection Reference Model (OSI model) was published. Then, in 1980, Digital, Intel and Xerox (the DIX consortium) published an open standard for Ethernet that was soon adopted as the basis of standardization by the IEEE and the ISO. IBM responded by proposing Token Ring as an alternative to Ethernet but kept such tight control over standardization that competitors were wary of using it. ARCNET was less expensive than either, more reliable, more flexible, and by the late 1980s it had a market share about equal to that of Ethernet. Tandy/Radio Shack offered ARCNET as an application and file sharing medium for their TRS-80 Model II, Model 12, Model 16, Tandy 6000, Tandy 2000, Tandy 1000 and Tandy 1200 computer models. There were also hooks in the Model 4P's ROM to boot from an ARCNET network.

When Ethernet moved from co-axial cable to twisted pair and an "interconnected stars" cabling topology based on active hubs, it became much more attractive. Easier cabling, combined with the greater raw speed of Ethernet (10 Mbit/s, as compared with 2.5 Mbit/s for ARCnet) helped to increase Ethernet demand, and as more companies entered the market the price of Ethernet started to fall—and ARCNET (and Token Ring) volumes tapered off.

ARCnet Plus and decline
In response to greater bandwidth needs, and the challenge of Ethernet, a new standard called ARCnet Plus was developed by Datapoint, and introduced in 1992. ARCnet Plus ran at 20 Mbit/s, and was backward compatible with original ARCnet equipment. However, by the time ARCnet Plus products were ready for the market, Ethernet had captured the majority of the network market, and there was little incentive for users to move back to ARCnet. As a result, very few ARCnet Plus products were ever produced. Those that were built, mainly by Datapoint, were expensive, and hard to find.

ARCNET was eventually standardized as ANSI ARCNET 878.1. It appears this was when the name changed from ARCnet to ARCNET. Other companies entered the market, notably Standard Microsystems who produced systems based on a single VLSI chip, originally developed as custom LSI for Datapoint, but later made available by Standard Microsystems to other customers. Datapoint eventually found itself in financial trouble and eventually moved into video conferencing and (later) custom programming in the embedded market.

Even though ARCNET is now rarely used for new general networks, the diminishing installed base still requires support - and it retains a niche in industrial control.

Description
Original ARCNET used RG-62/U coaxial cable of 93 Ω impedance and either passive or active hubs in a star-wired bus topology. At the time of its greatest popularity, this was a significant advantage of ARCNET over Ethernet. A star-wired bus was much easier to build and expand (and was more readily maintainable) than the clumsy linear bus Ethernet of the time. The "interconnected stars" cabling topology made it easy to add and remove nodes without taking down the whole network, and much easier to diagnose and isolate failures within a complex LAN.

Another significant advantage ARCNET had over Ethernet was cable distance. ARCNET coax cable runs could extend 2000 ft between active hubs or between an active hub and an end node, while the RG-58 (50Ω) 'thin' Ethernet most widely used at that time was limited to a maximum run of 185 m from end to end.

ARCNET had the disadvantage of requiring either an active or passive hub between nodes if there were more than two nodes in the network, while thin Ethernet allowed nodes to be spaced anywhere along the linear coax cable. However, ARCNET passive hubs were very inexpensive, being composed of a simple, small, unpowered box with four ports, wired together with nothing more than four discrete resistors, so the disadvantage was not significant. This disadvantage can also be seen as an advantage, often the cost of a 4 port ARCNET passive hub was less than cost of the 4 BNC Tee connectors and 2 terminators that thin Ethernet requires to connect 4 computers, and unlike BNC Tee connectors that could sometimes be hard to obtain in the early days of Ethernet, an ARCNET passive hub could be easily manufactured in the field with 9 readily available parts (4 connectors, 4 resistors and a box to put them in).

Passive hubs limited the distance between a node and an active hub to 100 ft. A passive hub could not be connected directly to another passive hub. Unused ports on both types of hubs had to be terminated with a special connector. This special connector, called a terminator, is nothing more than a BNC connector with a 93 ohm resistor in it. Thin Ethernet also requires nearly identical terminators at the 2 terminal ends, the only difference being Ethernet uses a 50 ohm resistor.

To reduce costs, while still allowing coverage over a wide area, a common practice was to use one or more interconnected active hubs, each of which provided coverage for nodes no more than 200 ft away. Cable was run from each port of the active hubs to a different location no more than 100 ft away. A passive hub would then be attached to the end of the cable, and cables would be run locally from the passive hub, allowing connection of up to three nodes. In this way, a single 8-port active hub could be used to connect 24 networked devices over an area not exceeding 400 ft in diameter.

ARCNET allowed only 255 nodes per network. Node IDs for LAN workstations were typically set by DIP switches on the network interface card. Larger networks would have to be split into smaller networks, and bridged. The small number of possible nodes and the need to manually configure IDs was a disadvantage compared with Ethernet, particularly as large enterprise networks became common.

To mediate access to the bus, ARCNET, like Token Ring, uses a token passing scheme, rather than the carrier sense multiple access approach of Ethernet. When peers are inactive, a single "token" message is passed around the network from machine to machine, and no peer is allowed to use the bus unless it has the token. If a particular peer wishes to send a message, it waits to receive the token, sends its message, and then passes the token on to the next station. Because ARCNET is implemented as a distributed star, the token cannot be passed machine to machine around a ring. Instead, each node is assigned an 8 bit address (usually via DIP switches), and when a new node joins the network a "reconfig" occurs, wherein each node learns the address of the node immediately above it. The token is then passed directly from one node to the next. Historically, each approach had its advantages: ARCNET added a small delay on an inactive network as a sending station waited to receive the token, but Ethernet's performance degraded drastically if too many peers attempted to broadcast at the same time, due to the time required for the slower processors of the day to process and recover from collisions. ARCNET had slightly lower best-case performance (viewed by a single stream), but was much more predictable. ARCNET also has the advantage that it achieved its best aggregate performance under the highest loading, approaching asymptotically its maximum throughput. While the best case performance was less than Ethernet, the general case was equivalent and the worst case was dramatically better. An Ethernet network could collapse when too busy due to excessive collisions. An ARCNET would keep on going at normal (or even better) throughput. Throughput on a multi-node collision-based Ethernet was limited to between 40% and 60% of bandwidth usage (depending on source). Although 2.5 Mbit/s ARCNET could at one time outperform a 10 Mbit/s Ethernet in a busy office on slow processors, ARCNET ultimately gave way to Ethernet as improved processor speeds reduced the impact of collisions on overall throughput, and Ethernet costs dropped.

In the early 1980s ARCNET was much cheaper than Ethernet, in particular for PCs. For example, in 1985 SMC sold ARCNET cards for around US$300 whilst an Ungermann-Bass Ethernet card plus transceiver could cost US$500.

Another significant difference is that ARCNET provides the sender with a concrete acknowledgment (or not) of successful delivery at the receiving end before the token passes on to the next node, permitting much faster fault recovery within the higher level protocols (rather than having to wait for a timeout on the expected replies). ARCnet also doesn't waste network time transmitting to a node not ready to receive the message, since an initial inquiry (done at hardware level) establishes that the recipient is able and ready to receive the larger message before it is sent across the bus.

One further advantage that ARCNET enjoyed over collision-based Ethernet is that it guarantees equitable access to the bus by everyone on the network. Although it might take a short time to get the token depending on the number of nodes and the size of the messages currently being sent about, you will always receive it within a predictable maximum time; thus it is deterministic. This made ARCNET an ideal real-time networking system, which explains its use in the embedded systems and process control markets. Token Ring has similar qualities, but is much more expensive to implement than ARCNET.

In spite of ARCNET's deterministic operation and historic suitability for real-time environments such as process control, the general availability of switched gigabit Ethernet and Quality of service capabilities in Ethernet switches has all but eliminated ARCNET today.

At first the system was deployed using RG-62/U coaxial cable (commonly used in IBM mainframe environments to connect 3270 terminals and controllers), but later added support for twisted pair and fibre media. At ARCNET's lower speeds (2.5 Mbit/s), Cat-3 cable is good enough to run ARCNET. Some ARCNET twisted-pair products supported cable runs over 2000 ft on standard Cat-3 cable, far beyond anything Ethernet could do on any kind of copper cable.

In the early 1990s, Thomas-Conrad Corporation developed a 100 Mbit/s topology called TCNS based on the ARCNET protocol, which also supported RG-62, twisted-pair, and fiber optic media. TCNS enjoyed some success until the availability of lower-cost 100 Mbit/s Ethernet put an end to the general deployment of ARCNET as a LAN protocol.

However, because of its simple, robust nature, ARCNET controllers are still sold and used in industrial, embedded, and automotive applications.

title: ARCNET


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Talk:Flora Brovina

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Lir: You had "women's activist" here. I believe that the extensive discussion on feminism justifies using this page instead. If not, we need to make a "women's activist" with content that justifies it as a separate page.

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title: Talk:Flora Brovina