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131-536: The ICON was widely used in the mid to late 1980s, but disappeared after that time with the widespread introduction of PCs and Apple Macintoshes . In 1981, four years after the first microcomputers for mainstream consumers appeared, the Ontario Ministry of Education sensed that microcomputers could be an important component of education. In June the Minister of Education , Bette Stephenson , announced

262-756: A protocol stack , often constructed per the OSI model, communications functions are divided up into protocol layers, where each layer leverages the services of the layer below it until the lowest layer controls the hardware that sends information across the media. The use of protocol layering is ubiquitous across the field of computer networking. An important example of a protocol stack is HTTP (the World Wide Web protocol) running over TCP over IP (the Internet protocols) over IEEE 802.11 (the Wi-Fi protocol). This stack

393-519: A trackball for mouse-like pointing support. Inside the case, the specification called for a processor and support systems to allow a multitasking operating system to be used, selecting the Intel 80186 as the CPU. Color graphics were specified, at least as an option, along with monochrome and color monitors on top. Voice synthesis was built in, and the keyboard provided for accented characters. Additionally,

524-464: A "'next generation' true 16-bit CPU", and with "More speed. More disk storage. More expansion" than the IBM PC or "other MS-DOS computers". While admitting in 1984 that many PC DOS programs did not work on the computer, the company stated that "the most popular, sophisticated software on the market" was available, either immediately or "over the next six months". Like IBM, Microsoft's apparent intention

655-535: A 32-bit operating system released during the 2000s can still operate many of the simpler programs written for the OS of the early 1980s without needing an emulator , though an emulator like DOSBox now has near-native functionality at full speed (and is necessary for certain games which may run too fast on modern processors). Additionally, many modern PCs can still run DOS directly, although special options such as USB legacy mode and SATA-to-PATA emulation may need to be set in

786-509: A Hitachi HD46505 SP video controller, supporting NAPLPS . The EGA monitor was mounted on top of a tilt-and-swivel mount, a welcome improvement on the PET. It also included TI 's TMS5220 speech chip, originally designed for the TI-99 , and would speak the vaguely obscene word "dhtick" when starting up. Early Microtel machines were dark brown, but the vast majority of examples in the classroom were

917-484: A clear provision for educational software or a plan for use. A series of Policy Memos followed outlining the Committee's views. Policy Memo 47 stated that computers are to be used creatively, and for information retrieval; at the time most systems were used solely for programming. They also announced funding for the development of educational software on an estimated 6000 machines. The Ministry decided that standardizing

1048-759: A commercial venture. Experience had shown that even if an operating system was technically superior to Windows, it would be a failure in the market ( BeOS and OS/2 for example). In 1989, Steve Jobs said of his new NeXT system, "It will either be the last new hardware platform to succeed, or the first to fail." Four years later in 1993, NeXT announced it was ending production of the NeXTcube and porting NeXTSTEP to Intel processors. Very early on in PC history, some companies introduced their own XT-compatible chipsets . For example, Chips and Technologies introduced their 82C100 XT Controller which integrated and replaced six of

1179-491: A computer capable of running programs that are managed by MS-DOS". The main reason why an IBM standard is not worrying is that it can help competition to flourish. IBM will soon be as much a prisoner of its standards as its competitors are. Once enough IBM machines have been bought, IBM cannot make sudden changes in their basic design; what might be useful for shedding competitors would shake off even more customers. In February 1984 Byte wrote that "IBM's burgeoning influence in

1310-558: A consumer PC manufacturer during April 2005, when it sold its laptop and desktop PC divisions ( ThinkPad / ThinkCentre ) to Lenovo for US$ 1.75 billion . As of October 2007, Hewlett-Packard and Dell had the largest shares of the PC market in North America. They were also successful overseas, with Acer , Lenovo , and Toshiba also notable. Worldwide, a huge number of PCs are " white box " systems assembled by myriad local systems builders. Despite advances of computer technology,

1441-503: A diverse set of networking capabilities. The protocols have a flat addressing scheme. They operate mostly at layers 1 and 2 of the OSI model. For example, MAC bridging ( IEEE 802.1D ) deals with the routing of Ethernet packets using a Spanning Tree Protocol . IEEE 802.1Q describes VLANs , and IEEE 802.1X defines a port-based network access control protocol, which forms the basis for the authentication mechanisms used in VLANs (but it

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1572-531: A few percentage points of market share was Apple Inc. 's Macintosh . The Mac started out billed as "the computer for the rest of us", but high prices and closed architecture drove the Macintosh into an education and desktop publishing niche, from which it only emerged in the mid-2000s. By the mid-1990s the Mac's market share had dwindled to around 5% and introducing a new rival operating system had become too risky

1703-538: A floppy if needed. This contrasts with the system seen on PET computers of the same era, where the user saved files directly to the shared floppy as if they were attached to the local machine. Both the client and server ran the Unix-like QNX as their operating system with the addition of network file-sharing, the basic portions of it embedded in ROM . To this they added a NAPLPS /Telidon-based graphics system, which

1834-440: A large, congested network into an aggregation of smaller, more efficient networks. A router is an internetworking device that forwards packets between networks by processing the addressing or routing information included in the packet. The routing information is often processed in conjunction with the routing table . A router uses its routing table to determine where to forward packets and does not require broadcasting packets which

1965-719: A machine, Robert Arn, a member of the CATA team, set up CEMCORP , the Canadian Educational Microprocessor Corporation . When the specification was announced in 1983, CEMCORP was announced as the winner of a $ 10 million contract to develop and supply the initial machines. An additional $ 5 million in funding was announced to cover development of new software applications, while the Ontario Institute for Studies in Education (OISE)

2096-505: A minor player with its own technology". The Economist predicted in 1983 that "IBM will soon be as much a prisoner of its standards as its competitors are", because "Once enough IBM machines have been bought, IBM cannot make sudden changes in their basic design; what might be useful for shedding competitors would shake off even more customers". After the Compaq Deskpro 386 became the first 80386-based PC, PC wrote that owners of

2227-527: A more nondescript beige. The fileserver, sometimes referred to as the LexICON , was a simple rectangular box with an internal 10MB hard drive and a 5.25" floppy drive opening to the front, and parallel port for a shared printer. Later Lexicons included a 64MB hard disk, divided into two partitions. User accounts on the ICON were created on the hard drive, and the users had to use Unix commands to copy files to

2358-440: A multi-port bridge. Switches normally have numerous ports, facilitating a star topology for devices, and for cascading additional switches. Bridges and switches operate at the data link layer (layer 2) of the OSI model and bridge traffic between two or more network segments to form a single local network. Both are devices that forward frames of data between ports based on the destination MAC address in each frame. They learn

2489-524: A proprietary operating system : "Who cares? If IBM does it, they will most likely just isolate themselves from the largest marketplace, in which they really can't compete anymore anyway". He predicted that in 1987 the market "will complete its transition from an IBM standard to an Intel/MS-DOS/expansion bus standard ... Folks aren't so much concerned about IBM compatibility as they are about Lotus 1-2-3 compatibility". By 1992, Macworld stated that because of clones, "IBM lost control of its own market and became

2620-421: A range of machines from different vendors that had widely varying hardware. Those customers who needed other applications than the starter programs could reasonably expect publishers to offer their products for a variety of computers, on suitable media for each. Microsoft's competing OS was intended initially to operate on a similar varied spectrum of hardware, although all based on the 8086 processor. Thus, MS-DOS

2751-457: A repeater hub assists with collision detection and fault isolation for the network. Hubs and repeaters in LANs have been largely obsoleted by modern network switches. Network bridges and network switches are distinct from a hub in that they only forward frames to the ports involved in the communication whereas a hub forwards to all ports. Bridges only have two ports but a switch can be thought of as

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2882-418: A single failure can cause the network to fail entirely. In general, the more interconnections there are, the more robust the network is; but the more expensive it is to install. Therefore, most network diagrams are arranged by their network topology which is the map of logical interconnections of network hosts. Common topologies are: The physical layout of the nodes in a network may not necessarily reflect

3013-403: A standard voice telephone line. Modems are still commonly used for telephone lines, using a digital subscriber line technology and cable television systems using DOCSIS technology. A firewall is a network device or software for controlling network security and access rules. Firewalls are inserted in connections between secure internal networks and potentially insecure external networks such as

3144-877: A transmission medium. Power line communication uses a building's power cabling to transmit data. The following classes of wired technologies are used in computer networking. Network connections can be established wirelessly using radio or other electromagnetic means of communication. The last two cases have a large round-trip delay time , which gives slow two-way communication but does not prevent sending large amounts of information (they can have high throughput). Apart from any physical transmission media, networks are built from additional basic system building blocks, such as network interface controllers , repeaters , hubs , bridges , switches , routers , modems, and firewalls . Any particular piece of equipment will frequently contain multiple building blocks and so may perform multiple functions. A network interface controller (NIC)

3275-406: A variety of network topologies . The nodes of a computer network can include personal computers , servers , networking hardware , or other specialized or general-purpose hosts . They are identified by network addresses and may have hostnames . Hostnames serve as memorable labels for the nodes and are rarely changed after initial assignment. Network addresses serve for locating and identifying

3406-495: A variety of different sources, primarily to support circuit-switched digital telephony . However, due to its protocol neutrality and transport-oriented features, SONET/SDH also was the obvious choice for transporting Asynchronous Transfer Mode (ATM) frames. Asynchronous Transfer Mode (ATM) is a switching technique for telecommunication networks. It uses asynchronous time-division multiplexing and encodes data into small, fixed-sized cells . This differs from other protocols such as

3537-657: A virtual system of links that run on top of the Internet . Overlay networks have been used since the early days of networking, back when computers were connected via telephone lines using modems, even before data networks were developed. The most striking example of an overlay network is the Internet itself. The Internet itself was initially built as an overlay on the telephone network . Even today, each Internet node can communicate with virtually any other through an underlying mesh of sub-networks of wildly different topologies and technologies. Address resolution and routing are

3668-477: A white elephant scorned by boards and shunned by teachers.... Computer resources were forced upon the school system as a result of a top-down government decision that was taken precipitously and without research. The Ministry ceased all support for the ICON in 1994, making it orphaned technology , and the Archives of Ontario declined to take ICON hardware and copies of the ICON software, which were destroyed. This

3799-527: A year, using off the shelf parts, the hardware manufactured by Microtel and operating system from Quantum Software Systems . The original Microtel machines were first introduced to Ontario schools in 1984 in small numbers, packaged in a short-lived dark brown case. At this point Burroughs Canada was brought in to sell and support the machine. Soon, Sperry and Burroughs merged to form Unisys in 1986. Several generations of ICON machines were produced, evolving steadily to become more PC-like. They were built into

3930-522: Is computer hardware that connects the computer to the network media and has the ability to process low-level network information. For example, the NIC may have a connector for plugging in a cable, or an aerial for wireless transmission and reception, and the associated circuitry. In Ethernet networks, each NIC has a unique Media Access Control (MAC) address —usually stored in the controller's permanent memory. To avoid address conflicts between network devices,

4061-416: Is a similar description that is more commonly used for modern computers. The designation "PC", as used in much of personal computer history , has not meant "personal computer" generally, but rather an x86 computer capable of running the same software that a contemporary IBM or Lenovo PC could. The term was initially in contrast to the variety of home computer systems available in the early 1980s, such as

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4192-422: Is a virtual network that is built on top of another network. Nodes in the overlay network are connected by virtual or logical links. Each link corresponds to a path, perhaps through many physical links, in the underlying network. The topology of the overlay network may (and often does) differ from that of the underlying one. For example, many peer-to-peer networks are overlay networks. They are organized as nodes of

4323-566: Is also found in WLANs ) – it is what the home user sees when the user has to enter a "wireless access key". Ethernet is a family of technologies used in wired LANs. It is described by a set of standards together called IEEE 802.3 published by the Institute of Electrical and Electronics Engineers. Wireless LAN based on the IEEE 802.11 standards, also widely known as WLAN or WiFi, is probably

4454-478: Is an electronic device that receives a network signal , cleans it of unnecessary noise and regenerates it. The signal is retransmitted at a higher power level, or to the other side of obstruction so that the signal can cover longer distances without degradation. In most twisted-pair Ethernet configurations, repeaters are required for cable that runs longer than 100 meters. With fiber optics, repeaters can be tens or even hundreds of kilometers apart. Repeaters work on

4585-466: Is becoming a misnomer, as Intel has lost absolute control over the direction of x86 hardware development with AMD 's AMD64 . Additionally, non-Windows operating systems like macOS and Linux have established a presence on the x86 architecture. Although the IBM PC was designed for expandability, the designers could not anticipate the hardware developments of the 1980s, nor the size of the industry they would engender. To make things worse, IBM's choice of

4716-412: Is inefficient for very big networks. Modems (modulator-demodulator) are used to connect network nodes via wire not originally designed for digital network traffic, or for wireless. To do this one or more carrier signals are modulated by the digital signal to produce an analog signal that can be tailored to give the required properties for transmission. Early modems modulated audio signals sent over

4847-404: Is not sending packets, the link can be filled with packets from other users, and so the cost can be shared, with relatively little interference, provided the link is not overused. Often the route a packet needs to take through a network is not immediately available. In that case, the packet is queued and waits until a link is free. The physical link technologies of packet networks typically limit

4978-459: Is used between the wireless router and the home user's personal computer when the user is surfing the web. There are many communication protocols, a few of which are described below. The Internet protocol suite , also called TCP/IP, is the foundation of all modern networking. It offers connection-less and connection-oriented services over an inherently unreliable network traversed by datagram transmission using Internet protocol (IP). At its core,

5109-567: The Accelerated Graphics Port (AGP). Descendants of the x86 IBM PC compatibles, namely 64-bit computers based on " x86-64 /AMD64" chips comprise the majority of desktop computers on the market as of 2021, with the dominant operating system being Microsoft Windows . Interoperability with the bus structure and peripherals of the original PC architecture may be limited or non-existent. Many modern computers are unable to use old software or hardware that depends on portions of

5240-585: The Amiga , have been relegated to niche, enthusiast markets. In the past, the most successful exception was Apple 's Macintosh platform, which used non-Intel processors from its inception. Although Macintosh was initially based on the Motorola 68000 series , then transitioned to the PowerPC architecture, Macintosh computers transitioned to Intel processors beginning in 2006. Until 2020 Macintosh computers shared

5371-461: The Apple II , TRS-80 , and Commodore 64 . Later, the term was primarily used in contrast to Commodore 's Amiga and Apple 's Macintosh computers. These "clones" duplicated almost all the significant features of the original IBM PC architectures. This was facilitated by IBM's choice of commodity hardware components , which were cheap, and by various manufacturers' ability to reverse-engineer

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5502-634: The BIOS firmware using a " clean room design " technique. Columbia Data Products built the first clone of the IBM personal computer , the MPC 1600 by a clean-room reverse-engineered implementation of its BIOS. Other rival companies, Corona Data Systems , Eagle Computer , and the Handwell Corporation were threatened with legal action by IBM, who settled with them. Soon after in 1982, Compaq released

5633-665: The Compaq Portable . The Compaq was the first sewing machine-sized portable computer that was essentially 100% PC-compatible. The court decision in Apple v. Franklin , was that BIOS code was protected by copyright law, but it could reverse-engineer the IBM BIOS and then write its own BIOS using clean room design . Note this was over a year after Compaq released the Portable. The money and research put into reverse-engineering

5764-626: The IBM PS/2 computer that overcame many of the technical limits of the XT/AT bus, but this was rarely used as the basis for IBM-compatible computers since it required license payments to IBM both for the PS/2 bus and any prior AT-bus designs produced by the company seeking a license. This was unpopular with hardware manufacturers and several competing bus standards were developed by consortiums, with more agreeable license terms. Various attempts to standardize

5895-462: The Institute of Electrical and Electronics Engineers (IEEE) maintains and administers MAC address uniqueness. The size of an Ethernet MAC address is six octets . The three most significant octets are reserved to identify NIC manufacturers. These manufacturers, using only their assigned prefixes, uniquely assign the three least-significant octets of every Ethernet interface they produce. A repeater

6026-433: The Intel 8088 for the CPU introduced several limitations for developing software for the PC compatible platform. For example, the 8088 processor only had a 20-bit memory addressing space . To expand PC s beyond one megabyte, Lotus, Intel, and Microsoft jointly created expanded memory (EMS), a bank-switching scheme to allow more memory provided by add-in hardware, and accessed by a set of four 16- kilobyte "windows" inside

6157-631: The Macintosh computers offered by Apple Inc. and used mainly for desktop publishing at the time, the aging 8-bit Commodore 64 which was selling for $ 150 by this time and became the world's bestselling computer, the 32-bit Commodore Amiga line used for television and video production and the 32-bit Atari ST used by the music industry. However, IBM itself lost the main role in the market for IBM PC compatibles by 1990. A few events in retrospect are important: Despite popularity of its ThinkPad set of laptop PC's, IBM finally relinquished its role as

6288-507: The Macintosh had kept significant market share without having compatibility with the IBM PC, although that changed during the Intel Macs era running Mac OS X , often dual-booting Windows with Boot Camp . IBM decided in 1980 to market a low-cost single-user computer as quickly as possible. On August 12, 1981, the first IBM PC went on sale. There were three operating systems (OS) available for it. The least expensive and most popular

6419-558: The Multimedia PC (MPC) standard was set during 1990. A PC that met the minimum MPC standard could be marketed with the MPC logo, giving consumers an easy-to-understand specification to look for. Software that could operate on the most minimally MPC-compliant PC would be guaranteed to operate on any MPC. The MPC level 2 and MPC level 3 standards were set later, but the term "MPC compliant" never became popular. After MPC level 3 during 1996, no further MPC standards were established. By

6550-477: The World Wide Web , digital video and audio , shared use of application and storage servers , printers and fax machines , and use of email and instant messaging applications. Computer networking may be considered a branch of computer science , computer engineering , and telecommunications , since it relies on the theoretical and practical application of the related disciplines. Computer networking

6681-528: The 20-bit addressing. Later, Intel CPUs had larger address spaces and could directly address 16 MB (80286) or more, causing Microsoft to develop extended memory (XMS) which did not require additional hardware. "Expanded" and "extended" memory have incompatible interfaces, so anyone writing software that used more than one megabyte had to provide for both systems for the greatest compatibility until MS-DOS began including EMM386, which simulated EMS memory using XMS memory. A protected mode OS can also be written for

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6812-480: The 386 in the Series III, while an "ICON-on-a-card" for PCs also appeared. The original ICON workstations were housed in a large wedge-shaped steel case, with a full-sized keyboard mounted slightly left-of-center and a trackball mounted to the right. A rubber bumper-strip ran along the front edge, a precaution against a particular type of cut users sometimes got from the PET's sharp case. Graphics were generated by

6943-432: The 80286, but DOS application compatibility was more difficult than expected, not only because most DOS applications accessed the hardware directly, bypassing BIOS routines intended to ensure compatibility, but also that most BIOS requests were made by the first 32 interrupt vectors, which were marked as "reserved" for protected mode processor exceptions by Intel. Video cards suffered from their own incompatibilities. There

7074-583: The BIOS setup utility. Computers using the UEFI might need to be set at legacy BIOS mode to be able to boot DOS. However, the BIOS/UEFI options in most mass-produced consumer-grade computers are very limited and cannot be configured to truly handle OSes such as the original variants of DOS. The spread of the x86-64 architecture has further distanced current computers' and operating systems' internal similarity with

7205-459: The BIOS was a calculated risk. At the same time, many manufacturers such as Tandy / RadioShack , Xerox , Hewlett-Packard , Digital Equipment Corporation , Sanyo , Texas Instruments , Tulip , Wang and Olivetti introduced personal computers that supported MS-DOS, but were not completely software- or hardware-compatible with the IBM PC. Tandy described the Tandy 2000 , for example, as having

7336-490: The GEMS requirements, which cut its purchase price from around CAD$ 2500 to a mere $ 495 (USD$ 2700 and $ 696) – less expensive than most existing microcomputers. The entire program was politically explosive throughout its gestation as a result, causing a continual stream of news stories. Critics complained that other machines could be bought for half the cost, but supporters pushed back that no other machine at that price point supported

7467-619: The GEMS specifications. The release of the IBM Personal Computer/AT in 1984 reopened the debate and made nightly news, as it used a newer and more advanced CPU than the ICON: the 80286. Around this time other platforms, such as the Waterloo PORT networking system, gained approval for the government support that had originally been the province of the ICON. The basic ICON design had reached "beta quality" after just over

7598-419: The IBM PC compatible architecture which are missing or do not have equivalents in modern computers. For example, computers which boot using Unified Extensible Firmware Interface -based firmware that lack a Compatibility Support Module, or CSM, required to emulate the old BIOS-based firmware interface, or have their CSMs disabled, cannot natively run MS-DOS since MS-DOS depends on a BIOS interface to boot. Only

7729-454: The IBM PC compatibles remained very much compatible with the original IBM PC computers, although most of the components implement the compatibility in special backward compatibility modes used only during a system boot . It was often more practical to run old software on a modern system using an emulator rather than relying on these features. In 2014 Lenovo acquired IBM's x86-based server ( System x ) business for US$ 2.1 billion . One of

7860-651: The IBM PC compatibles: try the package you want to use before you buy the computer." Companies modified their computers' BIOS to work with newly discovered incompatible applications, and reviewers and users developed stress tests to measure compatibility; by 1984 the ability to operate Lotus 1-2-3 and Flight Simulator became the standard, with compatibles specifically designed to run them. IBM believed that some companies such as Eagle, Corona, and Handwell infringed on its copyright, and after Apple Computer, Inc. v. Franklin Computer Corp. successfully forced

7991-489: The IBM PC's release. InfoWorld wrote on the first anniversary of the IBM PC that The dark side of an open system is its imitators. If the specs are clear enough for you to design peripherals, they are clear enough for you to design imitations. Apple ... has patents on two important components of its systems ... IBM, which reportedly has no special patents on the PC, is even more vulnerable. Numerous PC-compatible machines—the grapevine says 60 or more—have begun to appear in

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8122-1268: The IBM PC. At first, few clones other than Compaq's offered truly full compatibility. Jerry Pournelle purchased an IBM PC in mid-1983, " rotten keyboard and all", because he had "four cubic feet of unevaluated software, much of which won't run on anything but an IBM PC. Although a lot of machines claim to be 100 percent IBM PC compatible, I've yet to have one arrive ... Alas, a lot of stuff doesn't run with Eagle, Z-100, Compupro , or anything else we have around here". Columbia Data Products's November 1983 sales brochure stated that during tests with retail-purchased computers in October 1983, its own and Compaq's products were compatible with all tested PC software, while Corona and Eagle's were less compatible. Columbia University reported in January 1984 that Kermit ran without modification on Compaq and Columbia Data Products clones, but not on those from Eagle or Seequa. Other MS-DOS computers also required custom code. By December 1983 Future Computing stated that companies like Compaq, Columbia Data Products, and Corona that emphasized IBM PC compatibility had been successful, while non-compatible computers had hurt

8253-432: The IBM PC. Many companies were reluctant to have their products' PC compatibility tested. When PC Magazine requested samples from computer manufacturers that claimed to produce compatibles for an April 1984 review, 14 of 31 declined. Corona specified that "Our systems run all software that conforms to IBM PC programming standards. And the most popular software does." When a BYTE journalist asked to test Peachtext at

8384-440: The Internet protocol suite or Ethernet that use variable-sized packets or frames . ATM has similarities with both circuit and packet switched networking. This makes it a good choice for a network that must handle both traditional high-throughput data traffic, and real-time, low-latency content such as voice and video. ATM uses a connection-oriented model in which a virtual circuit must be established between two endpoints before

8515-574: The Internet. Firewalls are typically configured to reject access requests from unrecognized sources while allowing actions from recognized ones. The vital role firewalls play in network security grows in parallel with the constant increase in cyber attacks . A communication protocol is a set of rules for exchanging information over a network. Communication protocols have various characteristics. They may be connection-oriented or connectionless , they may use circuit mode or packet switching, and they may use hierarchical addressing or flat addressing. In

8646-592: The OEM versions of MS-DOS were virtually identical, except perhaps for the provision of a few utility programs. MS-DOS provided adequate functionality for character-oriented applications such as those that could have been implemented on a text-only terminal . Had the bulk of commercially important software been of this nature, low-level hardware compatibility might not have mattered. However, in order to provide maximum performance and leverage hardware features (or work around hardware bugs), PC applications quickly developed beyond

8777-455: The PC community is stifling innovation because so many other companies are mimicking Big Blue", but The Economist stated in November 1983, "The main reason why an IBM standard is not worrying is that it can help competition to flourish". By 1983, IBM had about 25% of sales of personal computers between $ 1,000 and $ 10,000 , and computers with some PC compatibility were another 25%. As

8908-548: The Spring 1983 COMDEX , Corona representatives "hemmed and hawed a bit, but they finally led me ... off in the corner where no one would see it should it fail". The magazine reported that "Their hesitancy was unnecessary. The disk booted up without a problem". Zenith Data Systems was bolder, bragging that its Z-150 ran all applications people brought to test with at the 1984 West Coast Computer Faire . Creative Computing in 1985 stated, "we reiterate our standard line regarding

9039-627: The actual data exchange begins. ATM still plays a role in the last mile , which is the connection between an Internet service provider and the home user. There are a number of different digital cellular standards, including: Global System for Mobile Communications (GSM), General Packet Radio Service (GPRS), cdmaOne , CDMA2000 , Evolution-Data Optimized (EV-DO), Enhanced Data Rates for GSM Evolution (EDGE), Universal Mobile Telecommunications System (UMTS), Digital Enhanced Cordless Telecommunications (DECT), Digital AMPS (IS-136/TDMA), and Integrated Digital Enhanced Network (iDEN). Routing

9170-470: The added bonus that it would help develop a local microcomputer industry. In order to make the new machine attractive, the Ministry agreed to fund up to 75% of the purchase price from their own budget. When the plan was first announced there was widespread concern among educators. Their main complaint is that the Ministry would select a standard that was not powerful enough for their needs. A secondary concern

9301-468: The association of physical ports to MAC addresses by examining the source addresses of received frames and only forward the frame when necessary. If an unknown destination MAC is targeted, the device broadcasts the request to all ports except the source, and discovers the location from the reply. Bridges and switches divide the network's collision domain but maintain a single broadcast domain. Network segmentation through bridging and switching helps break down

9432-472: The clone makers to stop using the BIOS. The Phoenix BIOS in 1984, however, and similar products such as AMI BIOS , permitted computer makers to legally build essentially 100%-compatible clones without having to reverse-engineer the PC BIOS themselves. A September 1985 InfoWorld chart listed seven compatibles with 256 KB RAM, two disk drives, and monochrome monitors for $ 1,495 to $ 2,320 , while

9563-423: The computer marketplace of the time. Until then Microsoft's business was based primarily on computer languages such as BASIC . The established small system operating software was CP/M from Digital Research which was in use both at the hobbyist level and by the more professional of those using microcomputers. To achieve such widespread use, and thus make the product viable economically, the OS had to operate across

9694-527: The computers would reduce maintenance costs, and allow for the development of consistent educational software. The Ministry contracted the Canadian Advanced Technology Alliance (CATA) to help develop specifications for the new system. Policy Memos 68–73 followed in early 1983, stating that none of the existing platforms had all the qualities needed to be truly universal. The idea of a new machine quickly gained currency, with

9825-549: The dominant market player only to be virtually wiped out by Intel a year later. Intel has been the uncontested leader ever since. As the "Wintel" platform gained dominance Intel gradually abandoned the practice of licensing its technologies to other chipset makers; in 2010 Intel was involved in litigation related to their refusal to license their processor bus and related technologies to other companies like Nvidia . Companies such as AMD and Cyrix developed alternative x86 CPUs that were functionally compatible with Intel's. Towards

9956-424: The early 1990s, but by this point were used almost entirely for running DOS and Windows programs. Throughout the project's lifetime it was subject to continual debate and much political rhetoric. A 1992 article on the topic complained: Bette Stephenson favoured top-down decision making and as a result got trapped by her tunnel vision. Her ICON computer fiasco drained millions from the provincial treasury and created

10087-584: The end of the 1990s, AMD was taking an increasing share of the CPU market for PCs. AMD even ended up playing a significant role in directing the development of the x86 platform when its Athlon line of processors continued to develop the classic x86 architecture as Intel deviated with its NetBurst architecture for the Pentium 4 CPUs and the IA-64 architecture for the Itanium set of server CPUs. AMD developed AMD64,

10218-472: The equivalent IBM PC cost $ 2,820 . The inexpensive Leading Edge Model D is even compatible with IBM proprietary diagnostic software, unlike the Compaq Portable. By 1986 Compute! stated that "clones are generally reliable and about 99 percent compatible", and a 1987 survey in the magazine of the clone industry did not mention software compatibility, stating that "PC by now has come to stand for

10349-649: The establishment of the Extended Industry Standard Architecture bus open standard by a consortium of IBM PC compatible vendors, redefining the 16-bit IBM AT bus as the Industry Standard Architecture (ISA) bus. Additional bus standards were subsequently adopted to improve compatibility between IBM PC compatibles, including the VESA Local Bus (VLB), Peripheral Component Interconnect (PCI), and

10480-620: The exception rather than the rule. Instead of placing importance on compatibility with the IBM PC, vendors began to emphasize compatibility with Windows . In 1993, a version of Windows NT was released that could operate on processors other than the x86 set. While it required that applications be recompiled, which most developers did not do, its hardware independence was used for Silicon Graphics (SGI) x86 workstations–thanks to NT's Hardware abstraction layer (HAL), they could operate NT (and its vast application library) . No mass-market personal computer hardware vendor dared to be incompatible with

10611-424: The first major extension not created by Intel, which Intel later adopted as x86-64 . During 2006 Intel began abandoning NetBurst with the release of their set of "Core" processors that represented a development of the earlier Pentium III. A major alternative to Wintel domination is the rise of alternative operating systems since the early 2000s, which marked as the start of the post-PC era . This would include both

10742-458: The hardware instead of making standard calls was faster, however; this was particularly relevant to games. Software addressing IBM PC hardware in this way would not run on MS-DOS machines with different hardware (for example, the PC-98 ). The IBM PC was sold in high enough volumes to justify writing software specifically for it, and this encouraged other manufacturers to produce machines that could use

10873-462: The hardware, for a variety of reasons: The first thing to think about when considering an IBM-compatible computer is, "How compatible is it?" In May 1983, Future Computing defined four levels of compatibility: During development, Compaq engineers found that Microsoft Flight Simulator would not run because of what subLOGIC 's Bruce Artwick described as "a bug in one of Intel's chips", forcing them to make their new computer bug compatible with

11004-496: The interfaces were made, but in practice, many of these attempts were either flawed or ignored. Even so, there were many expansion options, and despite the confusion of its users, the PC compatible design advanced much faster than other competing designs of the time, even if only because of its market dominance. During the 1990s, IBM's influence on PC architecture started to decline. "IBM PC compatible" becomes "Standard PC" in 1990s, and later " ACPI PC" in 2000s. An IBM-brand PC became

11135-471: The late 1990s, the success of Microsoft Windows had driven rival commercial operating systems into near-extinction, and had ensured that the "IBM PC compatible" computer was the dominant computing platform . This meant that if a developer made their software only for the Wintel platform, they would still be able to reach the vast majority of computer users. The only major competitor to Windows with more than

11266-428: The latest version of Windows, and Microsoft's annual WinHEC conferences provided a setting in which Microsoft could lobby for—and in some cases dictate—the pace and direction of the hardware of the PC industry. Microsoft and Intel had become so important to the ongoing development of PC hardware that industry writers began using the word Wintel to refer to the combined hardware-software system. This terminology itself

11397-487: The latter becoming the most popular. Because of the great number of third-party adapters and no standard for them, programming the PC could be difficult. Professional developers would operate a large test-suite of various known-to-be-popular hardware combinations. Meanwhile, consumers were overwhelmed by the competing, incompatible standards and many different combinations of hardware on offer. To give them some idea of what sort of PC they would need to operate their software,

11528-668: The literature as the physical medium ) used to link devices to form a computer network include electrical cable , optical fiber , and free space. In the OSI model , the software to handle the media is defined at layers 1 and 2 — the physical layer and the data link layer. A widely adopted family that uses copper and fiber media in local area network (LAN) technology are collectively known as Ethernet. The media and protocol standards that enable communication between networked devices over Ethernet are defined by IEEE 802.3 . Wireless LAN standards use radio waves , others use infrared signals as

11659-525: The market and competition grew IBM's influence diminished. In November 1985 PC Magazine stated "Now that it has created the [PC] market, the market doesn't necessarily need IBM for the machines. It may depend on IBM to set standards and to develop higher-performance machines, but IBM had better conform to existing standards so as to not hurt users". In January 1987, Bruce Webster wrote in Byte of rumors that IBM would introduce proprietary personal computers with

11790-540: The marketplace. By June 1983 PC Magazine defined "PC 'clone ' " as "a computer [that can] accommodate the user who takes a disk home from an IBM PC, walks across the room, and plugs it into the 'foreign' machine". Because of a shortage of IBM PCs that year, many customers purchased clones instead. Columbia Data Products produced the first computer more or less compatible with the IBM PC standard during June 1982, soon followed by Eagle Computer . Compaq announced its first product, an IBM PC compatible in November 1982,

11921-665: The means that allow mapping of a fully connected IP overlay network to its underlying network. Another example of an overlay network is a distributed hash table , which maps keys to nodes in the network. In this case, the underlying network is an IP network, and the overlay network is a table (actually a map ) indexed by keys. Overlay networks have also been proposed as a way to improve Internet routing, such as through quality of service guarantees achieve higher-quality streaming media . Previous proposals such as IntServ , DiffServ , and IP multicast have not seen wide acceptance largely because they require modification of all routers in

12052-464: The most popular were the Commodore PET which had a strong following in the new computer programming classes due to its tough all-in-one construction and built-in support for Microsoft BASIC , and the Apple II which had a wide variety of educational software, mostly aimed at early education. The Ministry wanted to encourage uses of microcomputers that supported its curriculum guidelines and

12183-415: The most well-known member of the IEEE 802 protocol family for home users today. IEEE 802.11 shares many properties with wired Ethernet. Synchronous optical networking (SONET) and Synchronous Digital Hierarchy (SDH) are standardized multiplexing protocols that transfer multiple digital bit streams over optical fiber using lasers. They were originally designed to transport circuit mode communications from

12314-511: The need for computer literacy for all students and formed the Advisory Committee on Computers in Education to guide their efforts. She stated that: It is now clear that one of the major goals that education must add to its list of purposes, is computer literacy. The world of the very near future requires that all of us have some understanding of the processes and uses of computers. According to several contemporary sources, Stephenson

12445-412: The network needs to deliver the user data, for example, source and destination network addresses , error detection codes, and sequencing information. Typically, control information is found in packet headers and trailers , with payload data in between. With packets, the bandwidth of the transmission medium can be better shared among users than if the network were circuit switched . When one user

12576-420: The network topology. As an example, with FDDI , the network topology is a ring, but the physical topology is often a star, because all neighboring connections can be routed via a central physical location. Physical layout is not completely irrelevant, however, as common ducting and equipment locations can represent single points of failure due to issues like fires, power failures and flooding. An overlay network

12707-729: The network. On the other hand, an overlay network can be incrementally deployed on end-hosts running the overlay protocol software, without cooperation from Internet service providers . The overlay network has no control over how packets are routed in the underlying network between two overlay nodes, but it can control, for example, the sequence of overlay nodes that a message traverses before it reaches its destination . For example, Akamai Technologies manages an overlay network that provides reliable, efficient content delivery (a kind of multicast ). Academic research includes end system multicast, resilient routing and quality of service studies, among others. The transmission media (often referred to in

12838-522: The new computer did not need to fear that future IBM products would be incompatible with the Compaq, because such changes would also affect millions of real IBM PCs: "In sticking it to the competition, IBM would be doing the same to its own people". After IBM announced the OS/2 -oriented PS/2 line in early 1987, sales of existing DOS-compatible PC compatibles rose, in part because the proprietary operating system

12969-494: The nodes by communication protocols such as the Internet Protocol . Computer networks may be classified by many criteria, including the transmission medium used to carry signals, bandwidth , communications protocols to organize network traffic , the network size, the topology, traffic control mechanisms, and organizational intent. Computer networks support many applications and services , such as access to

13100-617: The original IBM PC by introducing yet another processor mode with an instruction set modified for 64-bit addressing, but x86-64 capable processors also retain standard x86 compatibility. Computer network A computer network is a set of computers sharing resources located on or provided by network nodes . Computers use common communication protocols over digital interconnections to communicate with each other. These interconnections are made up of telecommunication network technologies based on physically wired, optical , and wireless radio-frequency methods that may be arranged in

13231-514: The original IBM PC, they use an Intel x86 central processing unit and are capable of using interchangeable commodity hardware , such as expansion cards . Initially such computers were referred to as PC clones , IBM clones or IBM PC clones , but the term "IBM PC compatible" is now a historical description only, as the vast majority of microcomputers produced since the 1990s are IBM compatible. IBM itself no longer sells personal computers, having sold its division to Lenovo in 2005. " Wintel "

13362-521: The original XT circuits: one 8237 DMA controller, one 8253 interrupt timer, one 8255 parallel interface controller, one 8259 interrupt controller, one 8284 clock generator, and one 8288 bus controller. Similar non-Intel chipsets appeared for the AT-compatibles, for example OPTi's 82C206 or 82C495XLC which were found in many 486 and early Pentium systems. The x86 chipset market was very volatile though. In 1993, VLSI Technology had become

13493-520: The physical layer of the OSI model but still require a small amount of time to regenerate the signal. This can cause a propagation delay that affects network performance and may affect proper function. As a result, many network architectures limit the number of repeaters used in a network, e.g., the Ethernet 5-4-3 rule . An Ethernet repeater with multiple ports is known as an Ethernet hub . In addition to reconditioning and distributing network signals,

13624-456: The protocol suite defines the addressing, identification, and routing specifications for Internet Protocol Version 4 (IPv4) and for IPv6 , the next generation of the protocol with a much enlarged addressing capability. The Internet protocol suite is the defining set of protocols for the Internet. IEEE 802 is a family of IEEE standards dealing with local area networks and metropolitan area networks. The complete IEEE 802 protocol suite provides

13755-509: The rapid growth of the smartphones (using Android or iOS) as an alternative to the personal computer; and the increasing prevalence of Linux and Unix-like operating systems in the server farms of large corporations such as Google or Amazon. The term "IBM PC compatible" is not commonly used presently because many current mainstream desktop and laptop computers are based on the PC architecture, and IBM no longer makes PCs. The competing hardware architectures have either been discontinued or, like

13886-542: The reputations of others like TI and DEC despite superior technology. At a San Francisco meeting it warned 200 attendees, from many American and foreign computer companies as well as IBM itself, to "Jump on the IBM PC-compatible bandwagon—quickly, and as compatibly as possible". Future Computing said in February 1984 that some computers were "press-release compatible", exaggerating their actual compatibility with

14017-539: The same effect, but this did not easily extend to the greater color depths and higher resolutions offered by SVGA adapters. An attempt at creating a standard named VESA BIOS Extensions (VBE) was made, but not all manufacturers used it. When the 386 was introduced, again a protected mode OS could be written for it. This time, DOS compatibility was much easier because of virtual 8086 mode . Unfortunately programs could not switch directly between them, so eventually, some new memory-model APIs were developed, VCPI and DPMI ,

14148-490: The same programs, expansion cards , and peripherals as the PC. The x86 computer marketplace rapidly excluded all machines which were not hardware-compatible or software-compatible with the PC. The 640 KB barrier on "conventional" system memory available to MS-DOS is a legacy of that period; other non-clone machines, while subject to a limit, could exceed 640 KB. Rumors of "lookalike," compatible computers, created without IBM's approval, began almost immediately after

14279-481: The same system architecture as their Wintel counterparts and could boot Microsoft Windows without a DOS Compatibility Card . However, with the transition to the internally developed ARM -based Apple silicon , they are again the exception to IBM compatibility. The processor speed and memory capacity of modern PCs are many orders of magnitude greater than they were for the original IBM PC and yet backwards compatibility has been largely maintained –

14410-515: The sharing of files and information, giving authorized users access to data stored on other computers. Distributed computing leverages resources from multiple computers across a network to perform tasks collaboratively. Most modern computer networks use protocols based on packet-mode transmission. A network packet is a formatted unit of data carried by a packet-switched network . Packets consist of two types of data: control information and user data (payload). The control information provides data

14541-484: The simple terminal applications that MS-DOS supported directly. Spreadsheets , WYSIWYG word processors , presentation software and remote communication software established new markets that exploited the PC's strengths, but required capabilities beyond what MS-DOS provided. Thus, from very early in the development of the MS-DOS software environment, many significant commercial software products were written directly to

14672-493: The size of packets to a certain maximum transmission unit (MTU). A longer message may be fragmented before it is transferred and once the packets arrive, they are reassembled to construct the original message. The physical or geographic locations of network nodes and links generally have relatively little effect on a network, but the topology of interconnections of a network can significantly affect its throughput and reliability. With many technologies, such as bus or star networks,

14803-569: The strengths of the PC-compatible design is its modular hardware design. End-users could readily upgrade peripherals and, to some degree, processor and memory without modifying the computer's motherboard or replacing the whole computer, as was the case with many of the microcomputers of the time. However, as processor speed and memory width increased, the limits of the original XT/AT bus design were soon reached, particularly when driving graphics video cards. IBM did introduce an upgraded bus in

14934-418: The systems would include no local storage at all, and would instead rely on a networked file server containing a hard drive . The specification was considerably in advance of the state of the art of the time, and when it was delivered commentators immediately reversed their earlier concerns and suggested the machine was too powerful, and would therefore be available in too small numbers. To deliver such

15065-463: The very successful Compaq Portable , also with a clean-room reverse-engineered BIOS, and also not challenged legally by IBM. Early IBM PC compatibles used the same computer buses as their IBM counterparts, switching from the 8-bit IBM PC and XT bus to the 16-bit IBM AT bus with the release of the AT. IBM's introduction of the proprietary Micro Channel architecture (MCA) in its PS/2 series resulted in

15196-404: The workstations. The workstations and servers were internally similar, based on Intel 80186 microprocessors running at 7.16 MHz, and connected to each other using ARCNET . Several upgrades were introduced into the ICON line over time. The ICON2 sported a redesigned case, a detached keyboard with integrated trackball, expanded RAM, and facilities for an internal hard disk. The CPU was upgraded to

15327-566: Was PC DOS made by Microsoft . In a crucial concession, IBM's agreement allowed Microsoft to sell its own version, MS-DOS , for non-IBM computers. The only component of the original PC architecture exclusive to IBM was the BIOS (Basic Input/Output System). IBM at first asked developers to avoid writing software that addressed the computer's hardware directly and to instead make standard calls to BIOS functions that carried out hardware-dependent operations. This software would run on any machine using MS-DOS or PC DOS. Software that directly addressed

15458-423: Was apparently too slow to use realistically. Helicon Systems also produced a MIDI interface for the original ICON. The biggest problem for the machine was a lack of software. The ICON was originally designed to let teachers create and share their own lessonware, using a simple hypertext-based system where pages could either link to other pages or run programs written in C. The "anyone can create lessonware" model

15589-402: Was asked to convert 30 existing programs to the new machine. In order to be able to afford what was expected to be an expensive machine, the Ministry announced a special "Recognized Extraordinary Expenditure" (REE) grant that would provide for up to 75% of the purchase costs of machines meeting the "Grant Eligible Microcomputer Systems" or "G.E.M.S." specifications. At the time, only the ICON met

15720-424: Was controversial in its own right, as others maintained that it could be sent to other schools that lacked extensive Information Technology. Despite the development of the ICON program, equality among schools was not assured because each school community could afford different capital outlays depending on the parents' affluence. The ICON system was based on a workstation / file server model, with no storage local to

15851-454: Was few and far between. The Ministry contracted for a number of applications, but the small target market and the sometimes difficult process required to secure such contracts were significant obstacles for realistic commercial development. IBM PC compatible " IBM PC–compatible " refers to a class of computers that are technically compatible with the 1981 IBM PC and subsequent XT and AT models from computer giant IBM . Like

15982-438: Was for several years sold only as an OEM product. There was no Microsoft-branded MS-DOS: MS-DOS could not be purchased directly from Microsoft, and each OEM release was packaged with the trade dress of the given PC vendor. Malfunctions were to be reported to the OEM, not to Microsoft. However, as machines that were compatible with IBM hardware—thus supporting direct calls to the hardware—became widespread, it soon became clear that

16113-462: Was influenced by a wide array of technological developments and historical milestones. Computer networks enhance how users communicate with each other by using various electronic methods like email, instant messaging, online chat, voice and video calls, and video conferencing. Networks also enable the sharing of computing resources. For example, a user can print a document on a shared printer or use shared storage devices. Additionally, networks allow for

16244-556: Was intended to be used with the trackball to make interactive programs. The system included a Paint programme that used the trackball, but did not include a usable GUI , although there were several attempts to produce one. QNX 2.0.1 included a modest one called "House", and another was built at least to the prototype stage by Helicon Systems in Toronto and appeared in one form as Ambience, though its capabilities were limited. A later upgrade called ICONLook improved upon this greatly, but it

16375-477: Was no standard interface for using higher-resolution SVGA graphics modes supported by later video cards. Each manufacturer developed their own methods of accessing the screen memory, including different mode numberings and different bank switching arrangements. The latter were used to address large images within a single 64 KB segment of memory. Previously, the VGA standard had used planar video memory arrangements to

16506-465: Was not available. In 1988, Gartner Group estimated that the public purchased 1.5 clones for every IBM PC. By 1989 Compaq was so influential that industry executives spoke of "Compaq compatible", with observers stating that customers saw the company as IBM's equal or superior. After 1987, IBM PC compatibles dominated both the home and business markets of commodity computers, with other notable alternative architectures being used in niche markets, like

16637-521: Was rejected by the Ministry of Education before the ICON shipped (in favour of a model under which the Ministry funded and controlled all lessonware), leaving the ICON with only the QNX command line interface and the Cemcorp-developed text editor application. The various Watcom programming languages were quickly ported to the system, but beyond that, the educational software teachers could expect

16768-467: Was that application writers would write to the application programming interfaces in MS-DOS or the firmware BIOS, and that this would form what would now be termed a hardware abstraction layer . Each computer would have its own Original Equipment Manufacturer (OEM) version of MS-DOS, customized to its hardware. Any software written for MS-DOS would operate on any MS-DOS computer, despite variations in hardware design. This expectation seemed reasonable in

16899-576: Was that the time delay between announcing and introducing the computer would be lengthy, a period in which existing purchases could be funded instead. The first set of concerns were rendered moot when the specifications were introduced in March 1983 in the "Functional Requirements for Microcomputers for Educational Use in Ontario Schools—Stage I." The physical design required a PET-like all-in-one case, headphones output for voice and sound effects, and

17030-510: Was the driving force behind the project; "whenever there was a problem she appears to have 'moved heaven and earth' to get it back on the tracks." The Ministry recognized that a small proportion of teachers and other school personnel were already quite involved with microcomputers and that some schools were acquiring first-generation machines. These acquisitions were uneven, varying in brand and model not just between school boards, but among schools within boards and even classroom to classroom. Among

17161-458: Was willing to underwrite the development of software for that purpose. However, the wide variety of machines being used meant that development costs had to be spread over several platforms. Additionally, many of the curriculum topics they wanted to cover required more storage or graphics capability than at least some of the machines then in use, if not all of them. Educational software was in its infancy, and many hardware acquisitions were made without

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