1.
Computer network
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A computer network or data network is a telecommunications network which allows nodes to share resources. In computer networks, networked computing devices exchange data with other using a data link. The connections between nodes are established using either cable media or wireless media, the best-known computer network is the Internet. Network computer devices that originate, route and terminate the data are called network nodes, nodes can include hosts such as personal computers, phones, servers as well as networking hardware. Two such devices can be said to be networked together when one device is able to exchange information with the other device, Computer networks differ in the transmission medium used to carry their signals, communications protocols to organize network traffic, the networks size, topology and organizational intent. In most cases, application-specific communications protocols are layered over other more general communications protocols and this formidable collection of information technology requires skilled network management to keep it all running reliably. The chronology of significant computer-network developments includes, In the late 1950s, in 1960, the commercial airline reservation system semi-automatic business research environment went online with two connected mainframes. Licklider developed a group he called the Intergalactic Computer Network. In 1964, researchers at Dartmouth College developed the Dartmouth Time Sharing System for distributed users of computer systems. The same year, at Massachusetts Institute of Technology, a group supported by General Electric and Bell Labs used a computer to route. Throughout the 1960s, Leonard Kleinrock, Paul Baran, and Donald Davies independently developed network systems that used packets to transfer information between computers over a network, in 1965, Thomas Marill and Lawrence G. Roberts created the first wide area network. This was an precursor to the ARPANET, of which Roberts became program manager. Also in 1965, Western Electric introduced the first widely used telephone switch that implemented true computer control, in 1972, commercial services using X.25 were deployed, and later used as an underlying infrastructure for expanding TCP/IP networks. In July 1976, Robert Metcalfe and David Boggs published their paper Ethernet, Distributed Packet Switching for Local Computer Networks, in 1979, Robert Metcalfe pursued making Ethernet an open standard. In 1976, John Murphy of Datapoint Corporation created ARCNET, a network first used to share storage devices. In 1995, the transmission speed capacity for Ethernet increased from 10 Mbit/s to 100 Mbit/s, by 1998, Ethernet supported transmission speeds of a Gigabit. Subsequently, higher speeds of up to 100 Gbit/s were added, the ability of Ethernet to scale easily is a contributing factor to its continued use. Providing access to information on shared storage devices is an important feature of many networks, a network allows sharing of files, data, and other types of information giving authorized users the ability to access information stored on other computers on the network
2.
Nanonetwork
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A nanonetwork or nanoscale network is a set of interconnected nanomachines, which are able to perform only very simple tasks such as computing, data storing, sensing and actuation. Nanonetworks are expected to expand the capabilities of single nanomachines both in terms of complexity and range of operation by allowing them to coordinate, share, nanonetworks enable new applications of nanotechnology in the biomedical field, environmental research, military technology and industrial and consumer goods applications. Nanoscale communication is defined in IEEE P1906.1, classical communication paradigms need to be revised for the nanoscale. The two main alternatives for communication in the nanoscale are based either on electromagnetic communication or on molecular communication and this is defined as the transmission and reception of electromagnetic radiation from components based on novel nanomaterials. For the time being, two alternatives for electromagnetic communication in the nanoscale have been envisioned. The different molecular communication techniques can be classified according to the type of propagation in walkaway-based, flow-based or diffusion-based communication. In walkway-based molecular communication, the molecules propagate through pre-defined pathways by using carrier substances and this type of molecular communication can also be achieved by using E. coli bacteria as chemotaxis. In flow-based molecular communication, the molecules propagate through diffusion in a medium whose flow and turbulence are guided. The hormonal communication through blood streams inside the body is an example of this type of propagation. The flow-based propagation can also be realized by using carrier entities whose motion can be constrained on the average along specific paths, a good example of this case is given by pheromonal long range molecular communications. In diffusion-based molecular communication, the molecules propagate through diffusion in a fluidic medium. In this case, the molecules can be solely to the laws of diffusion or can also be affected by non-predictable turbulence present in the fluidic medium. Pheromonal communication, when pheromones are released into a fluidic medium, other examples of this kind of transport include calcium signaling among cells, as well as quorum sensing among bacteria. Such temporal spreading has an impact in the performance of the system e. g. in creating the intersymbol interference at the receiving nanomachine. In order to detect the concentration-encoded molecular signal two detection methods named sampling-based detection and energy-based detection have been proposed, in order to reduce the impact of ISI a controlled pulse-width based molecular communication scheme has been analysed. The work presented in showed that it is possible to realize multilevel amplitude modulation based on ideal diffusion, a comprehensive study of pulse-based binary and sinus-based, concentration-encoded molecular communication system have also been investigated
3.
Near-field communication
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NFC devices are used in contactless payment systems, similar to those used in credit cards and electronic ticket smartcards and allow mobile payment to replace/supplement these systems. NFC is used for networking, for sharing contacts, photos, videos or files. NFC-enabled devices can act as electronic identity documents and keycards, NFC offers a low-speed connection with simple setup that can be used to bootstrap more capable wireless connections. Similar ideas in advertising and industrial applications were not generally successful commercially, outpaced by technologies such as barcodes, NFC protocols established a generally supported standard. When one of the devices has Internet connectivity, the other can exchange data with online services. NFC-enabled portable devices can be provided with software, for example to read electronic tags or make payments when connected to an NFC-compliant apparatus. NFC reader/writer—enables NFC-enabled devices to read information stored on inexpensive NFC tags embedded in labels or smart posters, NFC peer-to-peer—enables two NFC-enabled devices to communicate with each other to exchange information in an adhoc fashion. NFC tags are passive data stores which can be read, and under some circumstances written to and they typically contain data and are read-only in normal use, but may be rewritable. Applications include secure personal data storage, NFC tags can be custom-encoded by their manufacturers or use the industry specifications. The standards were provided by the NFC Forum, the forum was responsible for promoting the technology and setting standards and certifies device compliance. Secure communications are available by applying encryption algorithms as is done for credit cards, NFC standards cover communications protocols and data exchange formats and are based on existing radio-frequency identification standards including ISO/IEC14443 and FeliCa. The standards include ISO/IEC18092 and those defined by the NFC Forum, in addition to the NFC Forum, the GSMA group defined a platform for the deployment of GSMA NFC Standards within mobile handsets. GSMAs efforts include Trusted Services Manager, Single Wire Protocol, testing/certification, a patent licensing program for NFC is under deployment by France Brevets, a patent fund created in 2011. This program was under development by Via Licensing Corporation, an independent subsidiary of Dolby Laboratories, a platform-independent free and open source NFC library, libnfc, is available under the GNU Lesser General Public License. Present and anticipated applications include contactless transactions, data exchange and simplified setup of more complex such as Wi-Fi. This is used for identification, authentication and tracking,1983 The first patent to be associated with the abbreviation RFID was granted to Charles Walton. 1997 Early form patented and first used in Star Wars character toys for Hasbro, the patent was originally held by Andrew White and Marc Borrett at Innovision Research and Technology. The device allowed data communication between two units in close proximity,2002 Sony and Philips agreed to establish a technology specification and created a technical outline on March 25,2002
4.
Home network
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A home network or home area network is a type of computer network that facilitates communication among devices within the close vicinity of a home. Establishing this kind of network is necessary when there is need to distribute residential Internet access to all internet capable devices in the home. Due to the effect of IPv4 address exhaustion, most Internet service providers provide only a single WAN-facing IP address for each residential subscription, in homes these usually come in the form of a DSL modem or cable modem. A router manages network layer connectivity between a WAN and the HAN, most home networks feature a particular class of small, passively cooled, table-top device with an integrated wireless access point and 4 port Ethernet switch. These devices aim to make the installation, configuration, and management of a network as automated, user friendly. A network switch is used to allow devices on the network to talk to one another via Ethernet. While the needs of most home networks are satisfied with the built-in wireless and/or switching capabilities of their router, for example, When the routers switching capacity is exceeded. Most home routers expose only 4 to 6 Ethernet ports, most home networks rely on one wireless router combination device to fill this role. A home automation controller enables low-power wireless communications with simple, non-data-intensive devices such as light bulbs, a network bridge connecting two network interfaces to each other, often in order to grant a wired-only device, e. g. Xbox, access to a wireless network medium. Home networks can use either wired or wireless technologies to connect endpoints, wireless is the predominant option in homes due to the ease of installation, lack of unsightly cables, and network performance characteristics sufficient for residential activities. One of the most common ways of creating a network is by using wireless radio signal technology. Most wireless-capable residential devices operate at a frequency of 2.4 GHz under 802. 11b and 802. 11g or 5 GHz under 802. 11a, some home networking devices operate in both radio-band signals and fall within the 802. 11n or 802. 11ac standards. Wi-Fi is a marketing and compliance certification for IEEE802.11 technologies, the Wi-Fi Alliance has tested compliant products, and certifies them for interoperability. Low power, close range communication based on IEEE802.15 standards has a presence in homes. Bluetooth continues to be the technology of choice for most wireless accessories such as keyboards, mice, headsets and these connections are often established in a transient, ad-hoc manner and are not thought of as permanent residents of a home network. A low-rate version of the original WPAN protocol was used as the basis of ZigBee, ZigBee utilizes mesh networking to overcome the distance limitations associated with traditional WPAN in order to establish a single network of addressable devices spread across the entire building. Z-Wave is a standard also built on 802.15.4. Most wired network infrastructures found in homes utilize Category 5 or Category 6 twisted pair cabling with RJ45 compatible terminations and this medium provides physical connectivity between the Ethernet interfaces present on a large number of residential IP-aware devices
5.
Storage area network
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A storage area network is a network which provides access to consolidated, block level data storage. A SAN typically has its own network of devices that are generally not accessible through the local area network by other devices. The cost and complexity of SANs dropped in the early 2000s to levels allowing wider adoption across both enterprise and small to medium-sized business environments, a SAN does not provide file abstraction, only block-level operations. However, file systems built on top of SANs do provide file-level access, essentially, a SAN consolidates such storage islands together using a high-speed network. Operating systems maintain their own systems on their own dedicated, non-shared LUNs. If multiple systems were simply to attempt to share a LUN, any planned sharing of data on different computers within a LUN requires software, such as SAN file systems or clustered computing. Despite such issues, SANs help to increase capacity utilization. Common uses of a SAN include provision of transactionally accessed data that require high-speed block-level access to the hard drives such as servers, databases. Network-attached storage was designed independently of SAN systems, both NAS and SAN have the potential to reduce the amount of excess storage that must be purchased and provisioned as spare space. In a DAS-only architecture, each computer must be provisioned with enough storage to ensure that the computer does not run out of space at an untimely moment. In a DAS architecture the spare storage on one computer cannot be utilized by another, in a NAS the storage devices are directly connected to a file server that makes the storage available at a file-level to the other computers. In a SAN, the storage is available at a lower block-level. SAN protocols include Fibre Channel, iSCSI, ATA over Ethernet, instead the CPUs use the LAN to communicate, potentially creating bandwidth as well as performance bottlenecks. To understand their differences, a comparison of SAN, DAS and NAS architectures may be helpful, sharing storage usually simplifies storage administration and adds flexibility since cables and storage devices do not have to be physically moved to shift storage from one server to another. Other benefits include the ability to allow servers to boot from the SAN itself and this allows for a quick and easy replacement of faulty servers since the SAN can be reconfigured so that a replacement server can use the LUN of the faulty server. SANs also tend to more effective disaster recovery processes. A SAN could span a distant location containing a secondary storage array and this enables storage replication either implemented by disk array controllers, by server software, or by specialized SAN devices. Since IP WANs are often the least costly method of long-distance transport, the traditional physical SCSI layer could support only a few meters of distance - not nearly enough to ensure business continuance in a disaster
6.
Wireless LAN
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This gives users the ability to move around within a local coverage area and yet still be connected to the network. A WLAN can also provide a connection to the wider Internet, most modern WLANs are based on IEEE802.11 standards and are marketed under the Wi-Fi brand name. Wireless LANs have become popular for use in the home, due to their ease of installation and they are also popular in commercial complexes that offer wireless access to their customers. Norman Abramson, a professor at the University of Hawaii, developed the worlds first wireless communication network, ALOHAnet. The system included seven computers deployed over four islands to communicate with the computer on the Oahu Island without using phone lines. Wireless LAN hardware initially cost so much that it was used as an alternative to cabled LAN in places where cabling was difficult or impossible. Early development included industry-specific solutions and proprietary protocols, but at the end of the 1990s these were replaced by standards, beginning in 1991, a European alternative known as HiperLAN/1 was pursued by the European Telecommunications Standards Institute with a first version approved in 1996. This was followed by a HiperLAN/2 functional specification with ATM influences accomplished February 2000, in 2009802. 11n was added to 802.11. It operates in both the 2.4 GHz and 5 GHz bands at a data transfer rate of 600 Mbit/s. Most newer routers are able to utilise both wireless bands, known as dualband and this allows data communications to avoid the crowded 2.4 GHz band, which is also shared with Bluetooth devices and microwave ovens. The 5 GHz band is wider than the 2.4 GHz band, with more channels. Not all channels are available in all regions, a HomeRF group formed in 1997 to promote a technology aimed for residential use, but it disbanded at the end of 2002. All components that can connect into a medium in a network are referred to as stations. All stations are equipped with wireless network interface controllers, Wireless stations fall into two categories, wireless access points, and clients. Access points, normally wireless routers, are base stations for the wireless network and they transmit and receive radio frequencies for wireless enabled devices to communicate with. The basic service set is a set of all stations that can communicate with other at PHY layer. Every BSS has an identification called the BSSID, which is the MAC address of the access point servicing the BSS, there are two types of BSS, Independent BSS, and infrastructure BSS. An independent BSS is an ad hoc network that contains no access points, an extended service set is a set of connected BSSs
7.
Backbone network
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A backbone is a part of computer network that interconnects various pieces of network, providing a path for the exchange of information between different LANs or subnetworks. A backbone can tie together diverse networks in the building, in different buildings in a campus environment. Normally, the capacity is greater than the networks connected to it. The pieces of the connections that bring these departments together is often mentioned as network backbone. Network congestion is often taken into consideration while designing backbones, one example of a backbone network is the Internet backbone. This kind of topology allows for expansion and limited capital outlay for growth. Distributed backbones, in all practicality, are in use by all large-scale networks, applications in enterprise-wide scenarios confined to a single building are also practical, as certain connectivity devices can be assigned to certain floors or departments. Each floor or department possesses a LAN and a closet with that workgroups main hub or router connected to a bus-style network using backbone cabling. Another advantage of using a distributed backbone is the ability for network administrator to segregate workgroups for ease of management, there is the possibility of single points of failure, referring to connectivity devices high in the series hierarchy. The distributed backbone must be designed to separate network traffic circulating on each individual LAN from the network traffic by using access devices such as routers. A collapsed backbone is a type of network architecture. The traditional backbone network goes over the globe to provide interconnectivity to the remote hubs, in most cases, the backbones are the links while the switching or routing functions are done by the equipment at each hub. In the case of a collapsed or inverted backbone, each hub provides a back to a central location to be connected to a backbone-in-a-box. That box can be a switch or a router, the topology and architecture of a collapsed backbone is a star or a rooted tree. However, the drawback of the backbone is that if the box housing the backbone is down or there are reachability problem to the central location. These problems can be minimized by having redundant backbone boxes as well as having secondary/backup backbone locations, there are a few different types of backbones that are used for an enterprise-wide network. When organizations are looking for a strong and trustworthy backbone they should choose a parallel backbone. This backbone is a variation of a backbone in that it uses a central node
8.
Wide area network
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A wide area network is a telecommunications network or computer network that extends over a large geographical distance. Wide area networks are often established with leased telecommunication circuits, business, education and government entities use wide area networks to relay data among staff, students, clients, buyers, and suppliers from various locations across the world. In essence, this mode of telecommunication allows a business to carry out its daily function regardless of location. The Internet may be considered a WAN, the textbook definition of a WAN is a computer network spanning regions, countries, or even the world. WANs do not just necessarily connect physically disparate LANs, a CAN, for example, may have a localised backbone of a WAN technology, which connects different LANs within a campus. This could be to facilitate higher bandwidth applications, or provide better functionality for users in the CAN, WANs are used to connect LANs and other types of networks together, so that users and computers in one location can communicate with users and computers in other locations. Many WANs are built for one particular organization and are private, others, built by Internet service providers, provide connections from an organizations LAN to the Internet. WANs are often built using leased lines, at each end of the leased line, a router connects the LAN on one side with a second router within the LAN on the other. Leased lines can be very expensive, instead of using leased lines, WANs can also be built using less costly circuit switching or packet switching methods. Network protocols including TCP/IP deliver transport and addressing functions, protocols including Packet over SONET/SDH, Multiprotocol Label Switching, Asynchronous Transfer Mode and Frame Relay are often used by service providers to deliver the links that are used in WANs. X.25 was an important early WAN protocol, and is considered to be the grandfather of Frame Relay as many of the underlying protocols. Academic research into wide area networks can be broken down into three areas, mathematical models, network emulation and network simulation, performance improvements are sometimes delivered via wide area file services or WAN optimization. Many technologies are available for wide area network links, examples include circuit switched telephone lines, radio wave transmission, and optic fiber. New developments in technologies have successively increased transmission rates,1960, a 110 bit/s line was normal on the edge of the WAN, while core links of 56 kbit/s to 64 kbit/s were considered fast. AT&T plans to start conducting trials in the year 2017 for businesses to use 400 Gigabit Ethernet, researchers Robert Maher, Alex Alvarado, Domaniç Lavery & Polina Bayvel of University College London were able to increase networking speeds to 1.125 Terabits per second. Christos Santis, graduate student Scott Steger, Amnon Yariv, Martin, ATM Cable modem Dial-up DSL Frame relay ISDN Leased line SONET X.25 SD-WAN Cisco - Introduction to WAN Technologies
9.
Internet
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The Internet is the global system of interconnected computer networks that use the Internet protocol suite to link devices worldwide. The origins of the Internet date back to research commissioned by the United States federal government in the 1960s to build robust, the primary precursor network, the ARPANET, initially served as a backbone for interconnection of regional academic and military networks in the 1980s. Although the Internet was widely used by academia since the 1980s, Internet use grew rapidly in the West from the mid-1990s and from the late 1990s in the developing world. In the two decades since then, Internet use has grown 100-times, measured for the period of one year, newspaper, book, and other print publishing are adapting to website technology, or are reshaped into blogging, web feeds and online news aggregators. The entertainment industry was initially the fastest growing segment on the Internet, the Internet has enabled and accelerated new forms of personal interactions through instant messaging, Internet forums, and social networking. Business-to-business and financial services on the Internet affect supply chains across entire industries, the Internet has no centralized governance in either technological implementation or policies for access and usage, each constituent network sets its own policies. The term Internet, when used to refer to the global system of interconnected Internet Protocol networks, is a proper noun. In common use and the media, it is not capitalized. Some guides specify that the word should be capitalized when used as a noun, the Internet is also often referred to as the Net, as a short form of network. Historically, as early as 1849, the word internetted was used uncapitalized as an adjective, the designers of early computer networks used internet both as a noun and as a verb in shorthand form of internetwork or internetworking, meaning interconnecting computer networks. The terms Internet and World Wide Web are often used interchangeably in everyday speech, however, the World Wide Web or the Web is only one of a large number of Internet services. The Web is a collection of interconnected documents and other web resources, linked by hyperlinks, the term Interweb is a portmanteau of Internet and World Wide Web typically used sarcastically to parody a technically unsavvy user. The ARPANET project led to the development of protocols for internetworking, the third site was the Culler-Fried Interactive Mathematics Center at the University of California, Santa Barbara, followed by the University of Utah Graphics Department. In an early sign of growth, fifteen sites were connected to the young ARPANET by the end of 1971. These early years were documented in the 1972 film Computer Networks, early international collaborations on the ARPANET were rare. European developers were concerned with developing the X.25 networks, in December 1974, RFC675, by Vinton Cerf, Yogen Dalal, and Carl Sunshine, used the term internet as a shorthand for internetworking and later RFCs repeated this use. Access to the ARPANET was expanded in 1981 when the National Science Foundation funded the Computer Science Network, in 1982, the Internet Protocol Suite was standardized, which permitted worldwide proliferation of interconnected networks.5 Mbit/s and 45 Mbit/s. Commercial Internet service providers emerged in the late 1980s and early 1990s, the ARPANET was decommissioned in 1990
10.
Interplanetary Internet
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The interplanetary Internet is a conceived computer network in space, consisting of a set of network nodes that can communicate with each other. Communication would be delayed by the great interplanetary distances, so the IPN needs a new set of protocols and technology that are tolerant to large delays. This last phase has gone on since 1982 through the efforts of the Consultative Committee for Space Data Systems and it has 11 member agencies,22 observer agencies, and over 100 industrial associates. The evolution of space data system standards has gone on in parallel with the evolution of the Internet, with conceptual cross-pollination where fruitful, but largely as a separate evolution. Internet Protocol use without CCSDS has taken place on spacecraft, e. g. demonstrations on the UoSAT-12 satellite, and operationally on the Disaster Monitoring Constellation. Having reached the era where networking and IP on board spacecraft have shown to be feasible and reliable. The Interplanetary Internet study at NASAs Jet Propulsion Laboratory was started by a team of scientists at JPL led by Vinton Cerf, Cerf is one of the pioneers of the Internet on Earth, and currently holds the position of distinguished visiting scientist at JPL. Hooke was one of the founders and directors of CCSDS and it becomes apparent that the concept of a region is a natural architectural factoring of the Interplanetary Internet. A region is an area where the characteristics of communication are the same, region characteristics include communications, security, the maintenance of resources, perhaps ownership, and other factors. The Interplanetary Internet is a network of regional internets, what is needed then, is a standard way to achieve end-to-end communication through multiple regions in a disconnected, variable-delay environment using a generalized suite of protocols. Examples of regions might include the terrestrial Internet as a region, the recognition of this requirement led to the concept of a bundle as a high-level way to address the generalized Store-and-Forward problem. Delay-tolerant networking was designed to enable standardized communications over long distances, at its core is something called the Bundle Protocol, which is similar to the Internet Protocol, or IP, that serves as the heart of the Internet here on Earth. The Bundle Protocol was first tested in space on the UK-DMC satellite in 2008, an example of one of these end-to-end applications flown on a space mission is the CCSDS File Delivery Protocol, used on the comet mission, Deep Impact. CFDP is a standard for automatic, reliable file transfer in both directions. The dormant InterPlanetary Internet Special Interest Group of the Internet Society has worked on defining protocols, the Delay-Tolerant Networking Research Group is the primary group researching Delay-tolerant networking. Additional research efforts focus on various uses of the new technology, the canceled Mars Telecommunications Orbiter had been planned to establish an Interplanetary Internet link between Earth and Mars, in order to support other Mars missions. It would have used optical communications using laser beams for their higher data rates than radiowaves, in May 2009, DTN was deployed to a payload on board the ISS. NASA and BioServe Space Technologies, a group at the University of Colorado, have been continuously testing DTN on two Commercial Generic Bioprocessing Apparatus payloads
11.
Leased line
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A leased line is a private bidirectional or symmetric telecommunications line between two or more locations provided in exchange for a monthly rent. Sometimes known as a circuit or data line in the UK. Unlike traditional PSTN lines it does not have a telephone number, leased lines can be used for telephone, data or Internet services. Some are ringdown services, and some connect to a Private branch exchange or Router, typically, leased lines are used by businesses to connect geographically distant offices. Unlike dial-up connections, a line is always active. The fee for the connection is a monthly rate. The primary factors affecting the monthly fee are distance between end points and the speed of the circuit, because the connection does not carry anybody elses communications, the carrier can assure a given level of quality. An Internet leased line is an internet connectivity product, normally delivered over fiber. It is also known as a leased line, dedicated line. For example, a T-1 can be leased and provides a maximum speed of 1.544 Mbit/s. The user can channelize the T-1 to separate the 24 DS0 circuits for voice communication, partial the T-1 for data and voice communications, or multiplex the channels into a single data circuit. Leased lines, as opposed to DSL, are being used by companies, leased lines services became digital in the 1970s with the conversion of the Bell backbone network from analog to digital circuits. This allowed AT&T to offer Dataphone Digital Services that started the deployment of ISDN, leased lines were used to connect mainframe computers with terminals and remote sites, via IBM Systems Network Architecture or DECnet. With the extension of services in the 1980s leased lines were used to connect customer premises to Frame Relay or ATM networks. Access data rates increased from the original T1 option up to T3 circuits, leased lines are used to build up private networks, private telephone networks or access the internet or a partner network. Here is a review of the leased line applications in Network designs over time, note that other Layer 3 protocols were used such as Novell IPX on enterprise networks until TCP/IP became ubiquitous in the 2000s. Today, point to point data circuits are typically provisioned as either TDM, Ethernet, Terminating a leased line with two PBX allowed customers to by-pass PSTN for inter-site telephony. This allowed the customers to manage their own dial plan as well as to make significant savings if enough voice traffic was carried across the line, as demand grew on data network telcos started to build more advanced networks using packet switching on top of their infrastructure
12.
Ethernet
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Ethernet /ˈiːθərnɛt/ is a family of computer networking technologies commonly used in local area networks, metropolitan area networks and wide area networks. It was commercially introduced in 1980 and first standardized in 1983 as IEEE802.3, over time, Ethernet has largely replaced competing wired LAN technologies such as token ring, FDDI and ARCNET. The original 10BASE5 Ethernet uses coaxial cable as a medium, while the newer Ethernet variants use twisted pair. Over the course of its history, Ethernet data transfer rates have increased from the original 2.94 megabits per second to the latest 100 gigabits per second. The Ethernet standards comprise several wiring and signaling variants of the OSI physical layer in use with Ethernet, systems communicating over Ethernet divide a stream of data into shorter pieces called frames. As per the OSI model, Ethernet provides services up to, since its commercial release, Ethernet has retained a good degree of backward compatibility. Features such as the 48-bit MAC address and Ethernet frame format have influenced other networking protocols, the primary alternative for some uses of contemporary LANs is Wi-Fi, a wireless protocol standardized as IEEE802.11. Ethernet was developed at Xerox PARC between 1973 and 1974 and it was inspired by ALOHAnet, which Robert Metcalfe had studied as part of his PhD dissertation. In 1975, Xerox filed a patent application listing Metcalfe, David Boggs, Chuck Thacker, in 1976, after the system was deployed at PARC, Metcalfe and Boggs published a seminal paper. Metcalfe left Xerox in June 1979 to form 3Com and he convinced Digital Equipment Corporation, Intel, and Xerox to work together to promote Ethernet as a standard. The so-called DIX standard, for Digital/Intel/Xerox, specified 10 Mbit/s Ethernet, with 48-bit destination and source addresses and it was published on September 30,1980 as The Ethernet, A Local Area Network. Data Link Layer and Physical Layer Specifications, version 2 was published in November,1982 and defines what has become known as Ethernet II. Formal standardization efforts proceeded at the time and resulted in the publication of IEEE802.3 on June 23,1983. Ethernet initially competed with two largely proprietary systems, Token Ring and Token Bus, in the process, 3Com became a major company. 3Com shipped its first 10 Mbit/s Ethernet 3C100 NIC in March 1981, an Ethernet adapter card for the IBM PC was released in 1982, and, by 1985, 3Com had sold 100,000. Parallel port based Ethernet adapters were produced for a time, with drivers for DOS, by the early 1990s, Ethernet became so prevalent that it was a must-have feature for modern computers, and Ethernet ports began to appear on some PCs and most workstations. This process was sped up with the introduction of 10BASE-T and its relatively small modular connector. Since then, Ethernet technology has evolved to meet new bandwidth, in addition to computers, Ethernet is now used to interconnect appliances and other personal devices
13.
Wi-Fi
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Wi-Fi or WiFi is a technology for wireless local area networking with devices based on the IEEE802.11 standards. Wi-Fi is a trademark of the Wi-Fi Alliance, which restricts the use of the term Wi-Fi Certified to products that successfully complete interoperability certification testing. Devices that can use Wi-Fi technology include personal computers, video-game consoles, smartphones, digital cameras, tablet computers, digital audio players, Wi-Fi compatible devices can connect to the Internet via a WLAN network and a wireless access point. Such an access point has a range of about 20 meters indoors, hotspot coverage can be as small as a single room with walls that block radio waves, or as large as many square kilometres achieved by using multiple overlapping access points. Wi-Fi most commonly uses the 2.4 gigahertz UHF and 5 gigahertz SHF ISM radio bands, having no physical connections, it is more vulnerable to attack than wired connections, such as Ethernet. In 1971, ALOHAnet connected the Hawaiian Islands with a UHF wireless packet network, ALOHAnet and the ALOHA protocol were early forerunners to Ethernet, and later the IEEE802.11 protocols, respectively. A1985 ruling by the U. S. Federal Communications Commission released the ISM band for unlicensed use and these frequency bands are the same ones used by equipment such as microwave ovens and are subject to interference. In 1991, NCR Corporation with AT&T Corporation invented the precursor to 802.11, the first wireless products were under the name WaveLAN. They are the credited with inventing Wi-Fi. In 1992 and 1996, CSIRO obtained patents for a method used in Wi-Fi to unsmear the signal. The first version of the 802.11 protocol was released in 1997 and this was updated in 1999 with 802. 11b to permit 11 Mbit/s link speeds, and this proved to be popular. In 1999, the Wi-Fi Alliance formed as an association to hold the Wi-Fi trademark under which most products are sold. Wi-Fi uses a number of patents held by many different organizations. In April 2009,14 technology companies agreed to pay CSIRO $1 billion for infringements on CSIRO patents and this led to Australia labeling Wi-Fi as an Australian invention, though this has been the subject of some controversy. In 2016, the local area network Test Bed was chosen as Australias contribution to the exhibition A History of the World in 100 Objects held in the National Museum of Australia. The name Wi-Fi, commercially used at least as early as August 1999, was coined by the brand-consulting firm Interbrand, the Wi-Fi Alliance had hired Interbrand to create a name that was a little catchier than IEEE802. 11b Direct Sequence. Phil Belanger, a member of the Wi-Fi Alliance who presided over the selection of the name Wi-Fi, has stated that Interbrand invented Wi-Fi as a pun upon the word hi-fi. Interbrand also created the Wi-Fi logo, the yin-yang Wi-Fi logo indicates the certification of a product for interoperability
14.
Token ring
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Token ring local area network technology is a communications protocol for local area networks. It uses a special three-byte frame called a token that travels around a ring of workstations or servers. This token passing is an access method providing fair access for all stations. Proteon later evolved a 16 Mbit/s version that ran on unshielded twisted pair cable, IBM launched their own proprietary token ring product on October 15,1985. It ran at 4 Mbit/s, and attachment was possible from IBM PCs, midrange computers and it used a convenient star-wired physical topology, and ran over shielded twisted-pair cabling, and shortly thereafter became the basis for the /IEEE standard 802.5. During this time, IBM argued strongly that token ring LANs were superior to Ethernet, especially under load, but these claims were fiercely debated. In 1988 the faster 16 Mbit/s token ring was standardized by the 802.5 working group, Token ring does not inherently support this feature and requires additional software and hardware to operate on a direct cable connection setup. Token ring eliminates collision by the use of a single-use token, Token ring network interface cards contain all of the intelligence required for speed autodetection, routing and can drive themselves on many Multistation Access Units that operate without power. Ethernet network interface cards can operate on a passive hub to a degree, but not as a large LAN. Token ring employs access priority in which certain nodes can have priority over the token, unswitched Ethernet does not have provisioning for an access priority system as all nodes have equal contest for traffic. Multiple identical MAC addresses are supported on token ring, switched Ethernet cannot support duplicate MAC addresses without reprimand. Token Ring was more complex than Ethernet, requiring a specialized processor, by contrast, Ethernet included both the firmware and the lower licensing cost in the MAC chip. The cost of a token ring interface using the Texas Instruments TMS380C16 MAC, even more significant when comparing overall system costs was the much-higher cost of router ports and network cards for token-ring vs Ethernet. The emergence of Ethernet switches may have been the final straw, similar token passing mechanisms are used by ARCNET, token bus, 100VG-AnyLAN and FDDI, and they have theoretical advantages over the CSMA/CD of early Ethernet. A token ring network can be modeled as a system where a single server provides service to queues in a cyclic order. The data transmission process goes as follows, Empty information frames are continuously circulated on the ring, when a computer has a message to send, it seizes the token. The computer will then be able to send the frame, the frame is then examined by each successive workstation. The workstation that identifies itself to be the destination for the copies it from the frame
15.
AppleTalk
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AppleTalk was a proprietary suite of networking protocols developed by Apple Inc. for their Macintosh computers. AppleTalk includes a number of features that allow local area networks to be connected with no setup or the need for a centralized router or server of any sort. Connected AppleTalk-equipped systems automatically assign addresses, update the distributed namespace, AppleTalk was released in 1985, and was the primary protocol used by Apple devices through the 1980s and 1990s. Versions were also released for the IBM PC and compatibles and the Apple IIGS, AppleTalk support was also available in most networked printers, some file servers, and a number of routers. The rise of TCP/IP during the 1990s led to a reimplementation of most of these types of support on that protocol, many of AppleTalks more advanced autoconfiguration features have since been introduced in Bonjour, while Universal Plug and Play serves similar needs. After the release of the Apple Lisa computer in January 1983, known as AppleNet, it was based on the seminal Xerox XNS protocol stack but running on a custom 1 Mbit/s coaxial cable system rather than Xeroxs 2.94 Mbit/s Ethernet. AppleNet was announced early in 1983 with an introduction at the target price of $500 for plug-in AppleNet cards for the Lisa. At that time, early LAN systems were just coming to market, including Ethernet, Token Ring and this was a topic of major commercial effort at the time, dominating shows like the National Computer Conference in Anaheim in May 1983. All of the systems were jockeying for position in the market and it was at this show that Steve Jobs asked Gursharan Sidhu a seemingly innocuous question, Why has networking not caught on. Four months later, in October, AppleNet was cancelled, at the time, they announced that Apple realized that its not in the business to create a networking system. We built and used AppleNet in-house, but we realized if we had shipped it. In January, Jobs announced that they would instead be supporting IBMs Token Ring, through this period, Apple was deep in development of the Macintosh computer. During development, engineers had made the decision to use the Zilog 8530 serial controller chip instead of the lower cost and more common UART to provide serial port connections. The SCC cost about $5 more than a UART, but offered much higher speeds up to 250 kilobits per second, the SCC was chosen because it would allow multiple devices to be attached to the port. Peripherals equipped with similar SCCs could communicate using the built-in protocols and this would eliminate the need for more ports on the back of the machine, and allowed for the elimination of expansion slots for supporting more complex devices. The initial concept was known as AppleBus, envisioning a system controlled by the host Macintosh polling dumb devices in a similar to the modern Universal Serial Bus. The Macintosh team had begun work on what would become the LaserWriter. A series of memos from Bob Belleville clarified these concepts, outlining the Mac, LaserWriter, by late 1983 it was clear that IBMs Token Ring would not be ready in time for the launch of the Mac, and might miss the launch of these other products as well
16.
Lawrence Berkeley National Laboratory
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It is managed and operated by the University of California. The laboratory overlooks the University of California, Berkeleys main campus, the laboratory was founded in August 26,1931 by Ernest Lawrence as the Radiation Laboratory of the University of California, Berkeley associated with the Physics Department. It centered physics research around his new instrument, the cyclotron, throughout the 1930s, Lawrence pushed to create larger and larger machines for physics research, courting private philanthropists for funding. The lab moved to its site atop the hill above campus in 1940 as its machines, specifically the 184-inch cyclotron, lawrences lab helped contribute to what has been judged to be the three most valuable technology developments of the war. The cyclotron was finished in November 1946, the Manhattan Project shut down two months later, after the war, Lawrence maintained strong government and military ties at his lab, which became incorporated into the new system of Atomic Energy Commission National Laboratories. For security purposes, classified weapons research was assigned to the isolated locations, the Los Alamos National Laboratory in New Mexico. Livermore, about an hours drive southeast of Berkeley, was established at a naval air station in 1952 by Lawrence. Weapons-related and collaborative research continued at Berkeley Lab until the 1970s, shortly after the death of Lawrence in August 1958, the UC Radiation Laboratory was renamed the Lawrence Radiation Laboratory. The Berkeley location became the Lawrence Berkeley Laboratory in 1971, although continued to call it the Rad Lab. Gradually, another shortened form came into common usage, LBL and its formal name was amended to Ernest Orlando Lawrence Berkeley National Laboratory in 1995, when National was added to the names of all DOE labs. Ernest Orlando was later dropped to shorten the name, today, the lab is commonly referred to as Berkeley Lab. Over 1700 memos are available on-line, hosted by the Laboratory and it was Lawrence’s belief that scientific research is best done through teams of individuals with different fields of expertise, working together. His teamwork concept is a Berkeley Lab tradition that continues today, about 2,500 scientist-users carry out research at ALS every year. Berkeley Lab is proposing an upgrade of ALS which would increase the coherent flux of soft x-rays by two-three orders of magnitude, the Joint Genome Institute supports genomic research in support of the DOE missions in alternative energy, glocal carbon cycling, and environmental management. The JGIs partner laboratories are Berkeley Lab, Lawrence Livermore National Lab, Oak Ridge National Laboratory, Pacific Northwest National Laboratory, approximately 1,200 scientist-users take advantage of JGIs capabilities for their research every year. The Molecular Foundry is a multidisciplinary nanoscience research facility that provides users access to cutting-edge instrumentation. Approximately 700 scientist-users make use of facilities in their research every year. The National Energy Research Scientific Computing Center is the computing facility that provides large-scale state-of-the-art computing for the DOEs unclassified research programs
17.
Cambridge Ring (computer network)
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The Cambridge Ring was an experimental local area network architecture developed at the Computer Laboratory, University of Cambridge starting in 1974 and continuing into the 1980s. It was a network with a theoretical limit of 255 nodes. The network ran over twin twisted-pair cabling, people associated with the project include Andy Hopper, David Wheeler, Maurice Wilkes, and Roger Needham. In 2002 the Cambridge University Computer Laboratory launched a graduate society called the Cambridge Computer Lab Ring named after the Cambridge Ring, Cambridge Distributed Computing System Token ring Cambridge Ring Hardware Cambridge Fast Ring Cambridge Backbone Ring Hardware Cambridge Computer Lab Ring Ring PCB
18.
PARC (company)
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PARC, formerly Xerox PARC, is a research and development company in Palo Alto, California, with a distinguished reputation for its contributions to information technology and hardware systems. Xerox formed Palo Alto Research Center Incorporated as an owned subsidiary in 2002. Pake selected Palo Alto, California, as the site of what was to become known as PARC. S, the integration of Ethernet prompted the development of the PARC Universal Packet architecture, much like todays Internet. Xerox has been criticized for failing to properly commercialize and profitably exploit PARCs innovations. A favorite example is the user interface, initially developed at PARC for the Alto. Although very significant in terms of its influence on future system design, a small group from PARC led by David Liddle and Charles Irby formed Metaphor Computer Systems. They extended the Star desktop concept into a graphic and communicating office-automation model. Among PARCs distinguished researchers were three Turing Award winners, Butler W. Lampson, Alan Kay, and Charles P. Thacker. The Association for Computing Machinery Software System Award recognized the Alto system in 1984, Smalltalk in 1987, InterLisp in 1992, and the remote procedure call in 1994. Lampson, Kay, Bob Taylor, and Charles P. Thacker received the National Academy of Engineerings prestigious Charles Stark Draper Prize in 2004 for their work on the Alto, PARCs developments in information technology served for a long time as standards for much of the computing industry. Many advances were not equalled or surpassed for two decades, enormous timespans in the fast-paced high-tech world, a number of GUI engineers left to join Apple Computer. Work at PARC since the early 1980s includes advances in computing, aspect-oriented programming. Xerox Daybreak GlobalView Michael A. Hiltzik, Dealers of Lightning, Xerox PARC, alexander, Fumbling the Future, How Xerox Invented, Then Ignored, the First Personal Computer ISBN 1-58348-266-0 M. Mitchell Waldrop, The Dream Machine, J. C. R. Strassmann Charles Babbage Institute, University of Minnesota, Minneapolis Oral history interview with William Crowther Charles Babbage Institute, University of Minnesota, Minneapolis
19.
Datapoint
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Datapoint Corporation, originally known as Computer Terminal Corporation, was a computer company based in San Antonio, Texas, United States. At the time, mainframe computers were large room-filling pieces of equipment, for data was input using dumb. On the advice of one of his tutors from the University of Texas, Ray, after finding San Antonio, Texas based backers, the pair incorporated Computer Terminal Corporation there in July 1968. However, the resultant orders left the company with major problems, they had no production capacity. Furthermore, the TI chips within the 3300 were so unreliable, in October 1969, the company raised US$4 million through an Initial Public Offering. This enabled them to outsource production short term to a series of manufacturers, including a motorcycle helmet manufacturer. Once in production, they began sourcing chips from both TI and Intel, running up large debts from both, the Datapoint 3300 sold very successfully for a number of years. It was later rebadged as the DEC VT06 and the HP 2600A, having raised $4 million in an IPO in August 1969, selling over the counter for $8, by August 1970 the shares were selling at $45. They then asked Schmidt to write the accompanying communications software, pitching the idea to both TI and Intel, the partnership developed the Intel 8008, the forerunner of the microprocessor chips found in todays personal and computing devices. In December 1969 Poor joined CTC as Technical Director, employing Pyle within his team, Ray and Roche asked how much of their design could fit onto a computer chip. Poor and Pyle developed a project that would cost $100,000 to place their architecture onto silicon, in part this was fiscally driven, as both supplier debts were large, and the annulment of either would mean that CTC could avoid a second IPO. Noyce initially questioned the approach, suggesting that development of the microprocessor would reduce Intels sales of their dumb shift registers, the result was the development of the Intel 8008 microprocessor by Ted Hoff and Stan Mazor of Intel with IBMs Chief Scientist Larry Potter. The company began development on the Datapoint 2200, its most popular product, some users of the terminals chose to use them as simple programmable computers instead. In the end, Intel could not meet Datapoints product launch date, the 2200 had an optional disk drive using Shugart 8 floppies, single-sided, single-density which was the first commercial computer to include them. The Datapoint 2201 became so popular that CTC later changed its name to Datapoint Corp, despite the success of the 2200, the company lacked the finances and skills to manage its own production, and was hence quickly running out of cash. After Ray and Roche investigated and then dismissed selling the company, combined with other institutional share sales, this raised the required $7M to finance the development of a new product. However, on investigative audit the new investors found that Datapoints corporate accounts hid various holes and challenges, OKelley immediately realised that the TRW deal was fatally flawed. Effectively, it allowed TRW to manufacture outside North America, but then import the product, after renegotiations, OKelley and TRW agreed a new contract which allowed TRW to market the product outside North America, but not to manufacture it
20.
Chase Manhattan Bank
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The bank was known as Chase Manhattan Bank until it merged with J. P. Morgan & Co. in 2000. Chase Manhattan Bank was formed by the merger of the Chase National Bank, the bank has been headquartered in Columbus, Ohio since its merger with Bank One Corporation in 2004. The bank acquired the deposits and most assets of Washington Mutual, Chase offers more than 5,100 branches and 16,100 ATMs nationwide. JPMorgan Chase has 250,355 employees and operates in more than 100 countries, JPMorgan Chase currently has assets of roughly US$2.49 trillion. JPMorgan Chase, through its Chase subsidiary, is one of the Big Four banks of the United States. From September 1,1799, to 1955, it was called The Bank of The Manhattan Company, Chase National Bank was formed in 1877 by John Thompson. It was named after former United States Treasury Secretary and Chief Justice Salmon P. Chase, the Chase National Bank acquired a number of smaller banks in the 1920s, through its Chase Securities Corporation. In 1926, for instance, it acquired Mechanics and Metals National Bank, however, its most significant acquisition was the Equitable Trust Company of New York in 1930, the largest stockholder of which was John D. Rockefeller, Jr. This made Chase the largest bank in America and indeed, in the world, in 1955, Chase National Bank and The Manhattan Company merged to create The Chase Manhattan Bank. The deal was structured as an acquisition by the Bank of the Manhattan Company of Chase National. This avoided the need for consent by shareholders. For Chase Manhattan Banks new logo, Chermayeff & Geismar designed a stylized octagon in 1961, the Chase logo is a stylized representation of the primitive water pipes laid by the Manhattan Company, which were made by nailing together wooden planks. The bank included a management business called the Chase Investors Management Corporation. Under McCloys successor, George Champion, the bank relinquished its antiquated 1799 state charter for a modern one, in 1969, under the leadership of David Rockefeller, the bank became part of a bank holding company, the Chase Manhattan Corporation. In July 1996, Chemical Bank of New York purchased Chase Manhattan Bank, chemicals previous acquisitions included Manufacturers Hanover Corporation, in 1991, and Texas Commerce Bank, in 1987. Although Chemical was the survivor, the merged company retained the Chase name since it was better known. In December 2000, the combined Chase Manhattan completed the acquisition of J. P. Morgan & Co. in one of the largest banking mergers to date, the combined company was renamed JPMorgan Chase. In 2004, the bank acquired Bank One, making Chase the largest credit card issuer in the United States, JPMorgan Chase added Bear Stearns & Co. and Washington Mutual to its acquisitions in 2008 and 2009 respectively
21.
Personal computer
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A personal computer is a multi-purpose electronic computer whose size, capabilities, and price make it feasible for individual use. PCs are intended to be operated directly by a end-user, rather than by an expert or technician. In the 2010s, PCs are typically connected to the Internet, allowing access to the World Wide Web, personal computers may be connected to a local area network, either by a cable or a wireless connection. In the 2010s, a PC may be, a multi-component desktop computer, designed for use in a location a laptop computer, designed for easy portability or a tablet computer. In the 2010s, PCs run using a system, such as Microsoft Windows, Linux. The very earliest microcomputers, equipped with a front panel, required hand-loading of a program to load programs from external storage. Before long, automatic booting from permanent read-only memory became universal, in the 2010s, users have access to a wide range of commercial software, free software and free and open-source software, which are provided in ready-to-run or ready-to-compile form. Since the early 1990s, Microsoft operating systems and Intel hardware have dominated much of the computer market, first with MS-DOS. Alternatives to Microsofts Windows operating systems occupy a minority share of the industry and these include Apples OS X and free open-source Unix-like operating systems such as Linux and Berkeley Software Distribution. Advanced Micro Devices provides the alternative to Intels processors. PC is an initialism for personal computer, some PCs, including the OLPC XOs, are equipped with x86 or x64 processors but not designed to run Microsoft Windows. PC is used in contrast with Mac, an Apple Macintosh computer and this sense of the word is used in the Get a Mac advertisement campaign that ran between 2006 and 2009, as well as its rival, Im a PC campaign, that appeared in 2008. Since Apples transition to Intel processors starting 2005, all Macintosh computers are now PCs, the “brain” may one day come down to our level and help with our income-tax and book-keeping calculations. But this is speculation and there is no sign of it so far, in the history of computing there were many examples of computers designed to be used by one person, as opposed to terminals connected to mainframe computers. Using the narrow definition of operated by one person, the first personal computer was the ENIAC which became operational in 1946 and it did not meet further definitions of affordable or easy to use. An example of an early single-user computer was the LGP-30, created in 1956 by Stan Frankel and used for science and it came with a retail price of $47, 000—equivalent to about $414,000 today. Introduced at the 1965 New York Worlds Fair, the Programma 101 was a programmable calculator described in advertisements as a desktop computer. It was manufactured by the Italian company Olivetti and invented by the Italian engineer Pier Giorgio Perotto, the Soviet MIR series of computers was developed from 1965 to 1969 in a group headed by Victor Glushkov
22.
CP/M
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Initially confined to single-tasking on 8-bit processors and no more than 64 kilobytes of memory, later versions of CP/M added multi-user variations and were migrated to 16-bit processors. The combination of CP/M and S-100 bus computers was loosely patterned on the MITS Altair and this computer platform was widely used in business through the late 1970s and into the mid-1980s. CP/M increased the size for both hardware and software by greatly reducing the amount of programming required to install an application on a new manufacturers computer. An important driver of innovation was the advent of low-cost microcomputers running CP/M, as independent programmers and hackers bought them. CP/M was displaced by MS-DOS soon after the 1981 introduction of the IBM PC, manufacturers of CP/M-compatible systems customized portions of the operating system for their own combination of installed memory, disk drives, and console devices. CP/M would also run on based on the Zilog Z80 processor since the Z80 was compatible with 8080 code. CP/M used the 7-bit ASCII set, the other 128 characters made possible by the 8-bit byte were not standardized. For example, one Kaypro used them for Greek characters, WordStar used the 8th bit as an end-of-word marker. The BIOS and BDOS were memory-resident, while the CCP was memory-resident unless overwritten by an application, a number of transient commands for standard utilities were also provided. The transient commands resided in files with the extension. COM on disk, the BIOS directly controlled hardware components other than the CPU and main memory. It contained functions such as input and output and the reading and writing of disk sectors. The BDOS implemented the CP/M file system and some input/output abstractions on top of the BIOS, the CCP took user commands and either executed them directly or loaded and started an executable file of the given name. Third-party applications for CP/M were also essentially transient commands, the BDOS, CCP and standard transient commands were the same in all installations of a particular revision of CP/M, but the BIOS portion was always adapted to the particular hardware. Adding memory to a computer, for example, meant that the CP/M system had to be reinstalled with an updated BIOS capable of addressing the additional memory, a utility was provided to patch the supplied BIOS, BDOS and CCP to allow them to be run from higher memory. Once installed, the system was stored in reserved areas at the beginning of any disk which would be used to boot the system. On start-up, the bootloader would load the system from the disk in drive A. By modern standards CP/M was primitive, owing to the constraints on program size. With version 1.0 there was no provision for detecting a changed disk, if a user changed disks without manually rereading the disk directory the system would write on the new disk using the old disks directory information, ruining the data stored on the disk
23.
DOS
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None of these systems were officially named DOS, and indeed DOS is a general term for disk operating system. MS-DOS dominated the IBM PC compatible market between 1981 and 1995, and Microsoft Windows, still ran on top of it until about 2001, dozens of other operating systems also use the acronym DOS, including DOS/360 from 1966. Others are Apple DOS, Apple ProDOS, Atari DOS, Commodore DOS, TRSDOS, see List of DOS operating systems § Other operating systems. IBM PC DOS and its predecessor, 86-DOS, resembled Digital Researchs CP/M—the dominant disk operating system for 8-bit Intel 8080, DOS instead ran on Intel 8086 16-bit processors. Starting with MS-DOS1.28 and PC DOS2.0 the operating system incorporated various features inspired by Xenix, when IBM introduced the IBM PC, built with the Intel 8088 microprocessor, they needed an operating system. Seeking an 8088-compatible build of CP/M, IBM initially approached Microsoft CEO Bill Gates, IBM was sent to Digital Research, and a meeting was set up. However, the negotiations for the use of CP/M broke down, Digital Research wished to sell CP/M on a royalty basis, while IBM sought a single license. Digital Research founder Gary Kildall refused, and IBM withdrew, Gates in turn approached Seattle Computer Products. There, programmer Tim Paterson had developed a variant of CP/M-80, the system was initially named QDOS, before being made commercially available as 86-DOS. Microsoft purchased 86-DOS, allegedly for $50,000 and this became Microsoft Disk Operating System, MS-DOS, introduced in 1981. Within a year Microsoft licensed MS-DOS to over 70 other companies, Microsoft later required the use of the MS-DOS name, with the exception of the IBM variant. IBM continued to develop their version, PC DOS, for the IBM PC, Digital Research became aware that an operating system similar to CP/M was being sold by IBM, and threatened legal action. IBM responded by offering an agreement, they would give PC consumers a choice of PC DOS or CP/M-86, side-by-side, CP/M cost almost $200 more than PC DOS, and sales were low. CP/M faded, with MS-DOS and PC DOS becoming the operating system for PCs. Microsoft originally sold MS-DOS only to original equipment manufacturers, one major reason for this was that not all early PCs were 100% IBM PC compatible. DOS was structured such that there was a separation between the specific device driver code and the DOS kernel. Microsoft provided an OEM Adaptation Kit which allowed OEMs to customize the device driver code to their particular system, by the early 1990s, most PCs adhered to IBM PC standards so Microsoft began selling MS-DOS in retail with MS-DOS5.0. In the mid-1980s Microsoft developed a version of DOS
24.
Computer data storage
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Computer data storage, often called storage or memory, is a technology consisting of computer components and recording media used to retain digital data. It is a function and fundamental component of computers. The central processing unit of a computer is what manipulates data by performing computations, in practice, almost all computers use a storage hierarchy, which puts fast but expensive and small storage options close to the CPU and slower but larger and cheaper options farther away. In the Von Neumann architecture, the CPU consists of two parts, The control unit and the arithmetic logic unit. The former controls the flow of data between the CPU and memory, while the latter performs arithmetic and logical operations on data, without a significant amount of memory, a computer would merely be able to perform fixed operations and immediately output the result. It would have to be reconfigured to change its behavior and this is acceptable for devices such as desk calculators, digital signal processors, and other specialized devices. Von Neumann machines differ in having a memory in which they store their operating instructions, most modern computers are von Neumann machines. A modern digital computer represents data using the numeral system. Text, numbers, pictures, audio, and nearly any form of information can be converted into a string of bits, or binary digits. The most common unit of storage is the byte, equal to 8 bits, a piece of information can be handled by any computer or device whose storage space is large enough to accommodate the binary representation of the piece of information, or simply data. For example, the works of Shakespeare, about 1250 pages in print. Data is encoded by assigning a bit pattern to each character, digit, by adding bits to each encoded unit, redundancy allows the computer to both detect errors in coded data and correct them based on mathematical algorithms. A random bit flip is typically corrected upon detection, the cyclic redundancy check method is typically used in communications and storage for error detection. A detected error is then retried, data compression methods allow in many cases to represent a string of bits by a shorter bit string and reconstruct the original string when needed. This utilizes substantially less storage for many types of data at the cost of more computation, analysis of trade-off between storage cost saving and costs of related computations and possible delays in data availability is done before deciding whether to keep certain data compressed or not. For security reasons certain types of data may be encrypted in storage to prevent the possibility of unauthorized information reconstruction from chunks of storage snapshots. Generally, the lower a storage is in the hierarchy, the lesser its bandwidth and this traditional division of storage to primary, secondary, tertiary and off-line storage is also guided by cost per bit. In contemporary usage, memory is usually semiconductor storage read-write random-access memory, typically DRAM or other forms of fast but temporary storage
25.
Printer (computing)
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In computing, a printer is a peripheral which makes a persistent human-readable representation of graphics or text on paper or similar physical media. The worlds first computer printer was a 19th-century mechanically driven apparatus invented by Charles Babbage for his difference engine, the plotter was used for those requiring high quality line art like blueprints. Laser printers using PostScript mixed text and graphics, like dot-matrix printers, by 1990, most simple printing tasks like fliers and brochures were now created on personal computers and then laser printed, expensive offset printing systems were being dumped as scrap. The HP Deskjet of 1988 offered the same advantages as laser printer in terms of flexibility, inkjet systems rapidly displaced dot matrix and daisy wheel printers from the market. By the 2000s high-quality printers of this sort had fallen under the price point. Even the desire for printed output for offline reading while on mass transit or aircraft has been displaced by e-book readers, today, traditional printers are being used more for special purposes, like printing photographs or artwork, and are no longer a must-have peripheral. Starting around 2010, 3D printing became an area of intense interest and these devices are in their earliest stages of development and have not yet become commonplace. Personal printers are designed to support individual users, and may be connected to only a single computer. These printers are designed for low-volume, short-turnaround print jobs, requiring minimal setup time to produce a copy of a given document. However, they are generally slow devices ranging from 6 to around 25 pages per minute, however, this is offset by the on-demand convenience. Some printers can print documents stored on cards or from digital cameras. Networked or shared printers are designed for high-volume, high-speed printing and they are usually shared by many users on a network and can print at speeds of 45 to around 100 ppm. The Xerox 9700 could achieve 120 ppm, a virtual printer is a piece of computer software whose user interface and API resembles that of a printer driver, but which is not connected with a physical computer printer. It is called a printer by analogy with a printer which produces a two-dimensional document by a similar process of depositing a layer of ink on paper. The choice of print technology has an effect on the cost of the printer and cost of operation, speed, quality and permanence of documents. Some printer technologies dont work with certain types of physical media, cheques can be printed with liquid ink or on special cheque paper with toner anchorage so that alterations may be detected. The machine-readable lower portion of a cheque must be printed using MICR toner or ink, banks and other clearing houses employ automation equipment that relies on the magnetic flux from these specially printed characters to function properly. The following printing technologies are found in modern printers, A laser printer rapidly produces high quality text
26.
Communications protocol
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These are the rules or standard that defines the syntax, semantics and synchronization of communication and possible error recovery methods. Protocols may be implemented by hardware, software, or a combination of both, Communicating systems use well-defined formats for exchanging various messages. Each message has a meaning intended to elicit a response from a range of possible responses pre-determined for that particular situation. The specified behavior is independent of how it is to be implemented. Communications protocols have to be agreed upon by the parties involved, to reach agreement, a protocol may be developed into a technical standard. Multiple protocols often describe different aspects of a single communication, a group of protocols designed to work together are known as a protocol suite, when implemented in software they are a protocol stack. Most recent protocols are assigned by the IETF for Internet communication, the ITU-T handles telecommunications protocols and formats for the PSTN. As the PSTN and Internet converge, the two sets of standards are also being driven towards convergence, the nature of a communication, the actual data exchanged and any state-dependent behaviors, is defined by these specifications. In digital computing systems, the rules can be expressed by algorithms, expressing the algorithms in a portable programming language makes the protocol software operating-system independent. Operating systems usually contain a set of cooperating processes that manipulate shared data to communicate each other. This communication is governed by protocols, which can be embedded in the process code itself. In contrast, because there is no memory, communicating systems have to communicate with each other using a shared transmission medium. Transmission is not necessarily reliable, and individual systems may use different hardware or operating systems, to implement a networking protocol, the protocol software modules are interfaced with a framework implemented on the machines operating system. This framework implements the functionality of the operating system. The best known frameworks are the TCP/IP model and the OSI model and this gave rise to the concept of layered protocols which nowadays forms the basis of protocol design. Systems typically do not use a protocol to handle a transmission. Instead they use a set of cooperating protocols, sometimes called a family or protocol suite. Some of the best known protocol suites are TCP/IP, IPX/SPX, X.25, AX.25, the protocols can be arranged based on functionality in groups, for instance there is a group of transport protocols
27.
Windows NT
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Windows NT is a family of operating systems produced by Microsoft, the first version of which was released in July 1993. It is a processor-independent, multiprocessing, multi-user operating system, the first version of Windows NT was Windows NT3.1 and was produced for workstations and server computers. It was intended to complement consumer versions of Windows that were based on MS-DOS, gradually, the Windows NT family was expanded into Microsofts general-purpose operating system product line for all personal computers, deprecating the Windows 9x family. NT was formerly expanded to New Technology but no longer carries any specific meaning, starting with Windows 2000, NT was removed from the product name and is only included in the product version string. NT was the first purely 32-bit version of Windows, whereas its consumer-oriented counterparts, Windows 3. 1x and it is a multi-architecture operating system. Initially, it supported several CPU architectures, including IA-32, MIPS, DEC Alpha, PowerPC, the latest versions support x86 and ARM. This lineage is made clear in Cutlers foreword to Inside Windows NT by Helen Custer and it has been suggested that Dave Cutler intended the initialism WNT as a play on VMS, incrementing each letter by one. However, the project was intended as a follow-on to OS/2 and was referred to as NT OS/2 before receiving the Windows brand. One of the original NT developers, Mark Lucovsky, states that the name was taken from the original target processor—the Intel i860, the letters were dropped from the names of releases from Windows 2000 onwards, though Microsoft described that product as being Built on NT Technology. A main design goal of NT was hardware and software portability, the idea was to have a common code base with a custom Hardware Abstraction Layer for each platform. However, support for MIPS, Alpha, and PowerPC was later dropped in Windows 2000, broad software compatibility was achieved with support for several API personalities, including Windows API, POSIX, and OS/2 APIs – the latter two were phased out starting with Windows XP. Partial MS-DOS compatibility was achieved via an integrated DOS Virtual Machine – although this feature is being phased out in the x86-64 architecture, NT supported per-object access control lists allowing a rich set of security permissions to be applied to systems and services. NT supported Windows network protocols, inheriting the previous OS/2 LAN Manager networking, Windows NT3.1 was the first version of Windows to use 32-bit flat virtual memory addressing on 32-bit processors. Its companion product, Windows 3.1, used segmented addressing, notably, in Windows NT3. x, several I/O driver subsystems, such as video and printing, were user-mode subsystems. In Windows NT4, the video, server, and printer spooler subsystems were moved into kernel mode, NTFS, a journaled, secure file system, was created for NT. Windows NT also allows for other file systems, starting with versions 3.1. Windows NT introduced its own model, the Windows NT driver model. With Windows 2000, the Windows NT driver model was enhanced to become the Windows Driver Model, which was first introduced with Windows 98, but was based on the NT driver model
28.
Windows 3.1x
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Windows 3. 1x is a series of 16-bit operating environments produced by Microsoft for use on personal computers. The series began with Windows 3.1, which was first sold during April 1992 as a successor to Windows 3.0, subsequent versions were released between 1992 and 1994 until the series was superseded by Windows 95. Windows 3.1, released on April 6,1992, introduced a TrueType font system, similar functionality was available for Windows 3.0 through Adobe Type Manager font system from Adobe. Windows 3.1 was designed to have compatibility with older Windows platforms. As with Windows 3.0, version 3.1 had File Manager and Program Manager and it included Minesweeper as a replacement for Reversi. Windows 3.1 Multimedia PC Version included a viewer. It was targeted to the new Multimedia PC standard and included sound, Windows 3.1 dropped real mode support and required a minimum of a 286 PC with 1 MB of RAM to run. The effect of this was to increase system stability over the crash-prone Windows 3.0, some older features were removed, like CGA graphics support and compatibility with real mode Windows 2. x applications. Truetype font support was added, providing scalable fonts to Windows applications, Windows 3.1 included the following fonts, Arial, Courier New, Times New Roman, and Symbol in regular, bold, italic, and bold-italic versions. Truetype fonts could be scaled to any size and rotated, depending on the calling application, a few DOS applications, such as late releases of Microsoft Word, could access Windows Clipboard. Windows own drivers couldnt work directly with DOS applications, hardware such as mice required a DOS driver to be loaded before starting Windows, icons could be dragged and dropped for the first time, in addition to having a more detailed appearance. A file could be dragged onto Print Manager icon and the file would be printed by the current printer, assuming it was associated with a capable of printing. Alternatively, the file could be dragged out of File Manager, while Windows 3.0 was limited to 16 MB maximum memory, Windows 3.1 can access a theoretical 4 GB in 386 Enhanced Mode. However, no process can use more than 16 MB. File Manager was significantly improved over Windows 3.0, Multimedia support was enhanced over what was available in Windows 3.0 with Multimedia Extensions and available to all Windows 3.1 users. Windows 3.1 was available via 720 KB,1.2 MB, and 1.44 MB floppy distributions. It was also the first version of Windows to be distributed on CD-ROM — although this was common for Windows for Workgroups 3.11. Installed size on the disk was between 10 MB and 15 MB
29.
Microsoft
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Its best known software products are the Microsoft Windows line of operating systems, Microsoft Office office suite, and Internet Explorer and Edge web browsers. Its flagship hardware products are the Xbox video game consoles and the Microsoft Surface tablet lineup, as of 2016, it was the worlds largest software maker by revenue, and one of the worlds most valuable companies. Microsoft was founded by Paul Allen and Bill Gates on April 4,1975, to develop and it rose to dominate the personal computer operating system market with MS-DOS in the mid-1980s, followed by Microsoft Windows. The companys 1986 initial public offering, and subsequent rise in its share price, since the 1990s, it has increasingly diversified from the operating system market and has made a number of corporate acquisitions. In May 2011, Microsoft acquired Skype Technologies for $8.5 billion, in June 2012, Microsoft entered the personal computer production market for the first time, with the launch of the Microsoft Surface, a line of tablet computers. The word Microsoft is a portmanteau of microcomputer and software, Paul Allen and Bill Gates, childhood friends with a passion for computer programming, sought to make a successful business utilizing their shared skills. In 1972 they founded their first company, named Traf-O-Data, which offered a computer that tracked and analyzed automobile traffic data. Allen went on to pursue a degree in science at Washington State University. The January 1975 issue of Popular Electronics featured Micro Instrumentation and Telemetry Systemss Altair 8800 microcomputer, Allen suggested that they could program a BASIC interpreter for the device, after a call from Gates claiming to have a working interpreter, MITS requested a demonstration. Since they didnt actually have one, Allen worked on a simulator for the Altair while Gates developed the interpreter and they officially established Microsoft on April 4,1975, with Gates as the CEO. Allen came up with the name of Micro-Soft, as recounted in a 1995 Fortune magazine article. In August 1977 the company formed an agreement with ASCII Magazine in Japan, resulting in its first international office, the company moved to a new home in Bellevue, Washington in January 1979. Microsoft entered the OS business in 1980 with its own version of Unix, however, it was MS-DOS that solidified the companys dominance. For this deal, Microsoft purchased a CP/M clone called 86-DOS from Seattle Computer Products, branding it as MS-DOS, following the release of the IBM PC in August 1981, Microsoft retained ownership of MS-DOS. Since IBM copyrighted the IBM PC BIOS, other companies had to engineer it in order for non-IBM hardware to run as IBM PC compatibles. Due to various factors, such as MS-DOSs available software selection, the company expanded into new markets with the release of the Microsoft Mouse in 1983, as well as with a publishing division named Microsoft Press. Paul Allen resigned from Microsoft in 1983 after developing Hodgkins disease, while jointly developing a new OS with IBM in 1984, OS/2, Microsoft released Microsoft Windows, a graphical extension for MS-DOS, on November 20,1985. Once Microsoft informed IBM of NT, the OS/2 partnership deteriorated, in 1990, Microsoft introduced its office suite, Microsoft Office
30.
3Com
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3Com Corporation was a digital electronics manufacturer best known for its computer network infrastructure products. 3Com provided network interface controllers and switches, routers, wireless access points and controllers, IP voice systems, the company was based in Santa Clara, Calif. From its 2007 acquisition of 100 percent ownership of H3C Technologies Co, limited —initially a joint venture with China-based Huawei Technologies—3Com achieved a leading market presence in China, and a significant networking market share in Europe, Asia, and the Americas. 3Com products were sold under the brands 3Com, H3C, on April 12,2010, Hewlett-Packard completed the acquisition of 3Com. Since the acquisition, 3Com has been absorbed by Hewlett-Packard. After reading an article on ALOHAnet, Bob Metcalfe became interested in the topic of computer networking, ALOHAnet was an over-the-air wide area network system in Hawaii using UHF radios and made several assumptions that Metcalfe thought would not be correct in practice. He developed his own theories of how to traffic. In 1972 he joined Xerox PARC to develop ideas, and after pairing up with David Boggs. They then went on to build up a protocol known as PARC Universal Packet. At this point, Xerox management did nothing with it, even after being approached by prospective customers, increasingly upset by managements lack of interest, Metcalfe left Xerox in 1975, but was lured back again the next year. Further development followed, resulting in the seminal Xerox Network Systems protocol, once again, Metcalfe found management was unwilling to actually do anything with the product, and threatened to leave. Nothing followed, and in 1979 he left the company, Metcalfe subsequently co-founded 3Com in 1979. 3Com began making Ethernet adapter cards for many early 1980s computer systems, including the DEC LSI-11, DEC VAX-11 and these protocols were branded EtherShare, EtherPrint, EtherMail, and Ether-3270. The companys network software products included, 3+Share file and printer sharing, 3+Remote for routing XNS over a PC serial port. NetConnect for routing XNS between Ethernets, multiConnect was a chassis-based multi-port 10BASE2 Ethernet repeater. 3Server, a server-grade PC for running 3+ services, dynamicAccess software products for Ethernet load balancing, response time, and RMON II distributed monitoring. 3Coms expansion beyond its base of PC and thin Ethernet products began in 1987 when it merged with Bridge Communications. This provided a range of equipment based on Motorola 68000 processors, cS/1, CS/200 communication servers Ethernet bridges and XNS routers GS/1-X.25 X
31.
FTP
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The File Transfer Protocol is a standard network protocol used for the transfer of computer files from a server to a client using the Client–server model on a computer network. FTP is built on a model architecture and uses separate control. FTP users may authenticate themselves with a clear-text sign-in protocol, normally in the form of a username and password, for secure transmission that protects the username and password, and encrypts the content, FTP is often secured with SSL/TLS. SSH File Transfer Protocol is sometimes used instead, but is technologically different. The original specification for the File Transfer Protocol was written by Abhay Bhushan, until 1980, FTP ran on NCP, the predecessor of TCP/IP. The protocol was replaced by a TCP/IP version, RFC765 and RFC959. FTP may run in active or passive mode, which determines how the connection is established. In both cases, the client creates a TCP control connection from a random, usually an unprivileged, in active mode, the client starts listening for incoming data connections from the server on port M. It sends the FTP command PORT M to inform the server on which port it is listening, the server then initiates a data channel to the client from its port 20, the FTP server data port. In situations where the client is behind a firewall and unable to accept incoming TCP connections, both modes were updated in September 1998 to support IPv6. Further changes were introduced to the mode at that time. The server responds over the connection with three-digit status codes in ASCII with an optional text message. For example,200 means that the last command was successful, the numbers represent the code for the response and the optional text represents a human-readable explanation or request. An ongoing transfer of data over the data connection can be aborted using an interrupt message sent over the control connection. While transferring data over the network, four data representations can be used, ASCII mode, Data is converted, if needed, from the sending hosts character representation to 8-bit ASCII before transmission, and to the receiving hosts character representation. As a consequence, this mode is inappropriate for files that contain other than plain text. Image mode, The sending machine sends each file byte by byte, EBCDIC mode, Used for plain text between hosts using the EBCDIC character set. Local mode, Allows two computers with identical setups to send data in a format without the need to convert it to ASCII
32.
Workstation
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A workstation is a special computer designed for technical or scientific applications. Intended primarily to be used by one person at a time, they are connected to a local area network. Workstations offered higher performance than mainstream personal computers, especially with respect to CPU and graphics, memory capacity, and multitasking capability. Typically, the factor is that of a desktop computer, consist of a high resolution display, a keyboard and a mouse at a minimum. Workstations were the first segment of the market to present advanced accessories. The increasing capabilities of mainstream PCs in the late 1990s have blurred the lines somewhat with technical/scientific workstations, perhaps the first computer that might qualify as a workstation was the IBM1620, a small scientific computer designed to be used interactively by a single person sitting at the console. One peculiar feature of the machine was that it lacked any actual arithmetic circuitry, to perform addition, it required a memory-resident table of decimal addition rules. This saved on the cost of logic circuitry, enabling IBM to make it inexpensive, the machine was code-named CADET and rented initially for $1000 a month. In 1965, IBM introduced the IBM1130 scientific computer, which was meant as the successor to the 1620, both of these systems came with the ability to run programs written in Fortran and other languages. Both the 1620 and the 1130 were built into roughly desk-sized cabinets, both were available with add-on disk drives, printers, and both paper-tape and punched-card I/O. A console typewriter for direct interaction was standard on each, early examples of workstations were generally dedicated minicomputers, a system designed to support a number of users would instead be reserved exclusively for one person. A notable example was the PDP-8 from Digital Equipment Corporation, regarded to be the first commercial minicomputer, Lisp Machines were commercialized beginning 1980 by companies like Symbolics, Lisp Machines, Texas Instruments and Xerox. The first computer designed for single-users, with high-resolution graphics facilities was the Xerox Alto developed at Xerox PARC in 1973, other early workstations include the Terak 8510/a, Three Rivers PERQ and the later Xerox Star. Meanwhile, DARPAs VLSI Project created several spinoff graphics products as well, notably the SGI3130 and it was not uncommon to differentiate the target market for the products, with Sun and Apollo considered to be network workstations, while the SGI machines were graphics workstations. As RISC microprocessors became available in the mid-1980s, these were adopted by many workstation vendors, workstations tended to be very expensive, typically several times the cost of a standard PC and sometimes costing as much as a new car. However, minicomputers sometimes cost as much as a house, additionally, workstations, given their more specialized nature, tend to have higher profit margins than commodity-driven PCs. Additionally, the companies that make the products tend to have very good repair/replacement plans, some low-cost workstations are still expensive by PC standards, but offer binary compatibility with higher-end workstations and servers made by the same vendor. This allows software development to take place on low-cost desktop machines, Graphics workstations often shipped with graphics accelerators
