History of computing hardware
The history of computing hardware covers the developments from early simple devices to aid calculation to modern day computers. Before the 20th century, most calculations were done by humans. Early mechanical tools to help humans with digital calculations, like the abacus, were called "calculating machines", called by proprietary names, or referred to as calculators; the machine operator was called the computer. The first aids to computation were purely mechanical devices which required the operator to set up the initial values of an elementary arithmetic operation manipulate the device to obtain the result. Computers represented numbers in a continuous form, for instance distance along a scale, rotation of a shaft, or a voltage. Numbers could be represented in the form of digits, automatically manipulated by a mechanical mechanism. Although this approach required more complex mechanisms, it increased the precision of results. A series of breakthroughs, such as miniaturized transistor computers, the integrated circuit, caused digital computers to replace analog computers.
The cost of computers became so low that by the 1990s, personal computers, in the 2000s, mobile computers, became ubiquitous. Devices have been used to aid computation for thousands of years using one-to-one correspondence with fingers; the earliest counting device was a form of tally stick. Record keeping aids throughout the Fertile Crescent included calculi which represented counts of items livestock or grains, sealed in hollow unbaked clay containers; the use of counting rods is one example. The abacus was early used for arithmetic tasks. What we now call the Roman abacus was used in Babylonia as early as c. 2700–2300 BC. Since many other forms of reckoning boards or tables have been invented. In a medieval European counting house, a checkered cloth would be placed on a table, markers moved around on it according to certain rules, as an aid to calculating sums of money. Several analog computers were constructed in ancient and medieval times to perform astronomical calculations; these included the south-pointing chariot from ancient China, the astrolabe and Antikythera mechanism from the Hellenistic world.
In Roman Egypt, Hero of Alexandria made mechanical devices including automata and a programmable cart. Other early mechanical devices used to perform one or another type of calculations include the planisphere and other mechanical computing devices invented by Abu Rayhan al-Biruni; the castle clock, a hydropowered mechanical astronomical clock invented by Ismail al-Jazari in 1206, was the first programmable analog computer. Ramon Llull invented the Lullian Circle: a notional machine for calculating answers to philosophical questions via logical combinatorics; this idea was taken up by Leibniz centuries and is thus one of the founding elements in computing and information science. Scottish mathematician and physicist John Napier discovered that the multiplication and division of numbers could be performed by the addition and subtraction of the logarithms of those numbers. While producing the first logarithmic tables, Napier needed to perform many tedious multiplications, it was at this point that he designed his'Napier's bones', an abacus-like device that simplified calculations that involved multiplication and division.
Since real numbers can be represented as distances or intervals on a line, the slide rule was invented in the 1620s, shortly after Napier's work, to allow multiplication and division operations to be carried out faster than was possible. Edmund Gunter built a calculating device with a single logarithmic scale at the University of Oxford, his device simplified arithmetic calculations, including multiplication and division. William Oughtred improved this in 1630 with his circular slide rule, he followed this up with the modern slide rule in 1632 a combination of two Gunter rules, held together with the hands. Slide rules were used by generations of engineers and other mathematically involved professional workers, until the invention of the pocket calculator. Wilhelm Schickard, a German polymath, designed a calculating machine in 1623 which combined a mechanised form of Napier's rods with the world's first mechanical adding machine built into the base; because it made use of a single-tooth gear there were circumstances in which its carry mechanism would jam.
A fire destroyed at least one of the machines in 1624 and it is believed Schickard was too disheartened to build another. In 1642, while still a teenager, Blaise Pascal started some pioneering work on calculating machines and after three years of effort and 50 prototypes he invented a mechanical calculator, he built twenty of these machines in the following ten years. Nine Pascalines have survived. A continuing debate exists over whether Schickard or Pascal should be regarded as the "inventor of the mechanical calculator" and the range of issues to be considered is discussed elsewhere. Gottfried Wilhelm von Leibniz invented the stepped reckoner and his famous stepped drum mechanism around 1672, he attempted to create a machine that could be used not only for addition and subtraction but would utilise a moveable carriage to enable long multiplicatio
History of the Internet
The history of the Internet begins with the development of electronic computers in the 1950s. Initial concepts of wide area networking originated in several computer science laboratories in the United States, United Kingdom, France; the U. S. Department of Defense awarded contracts as early as the 1960s, including for the development of the ARPANET project, directed by Robert Taylor and managed by Lawrence Roberts; the first message was sent over the ARPANET in 1969 from computer science Professor Leonard Kleinrock's laboratory at University of California, Los Angeles to the second network node at Stanford Research Institute. Packet switching networks such as the NPL network, ARPANET, Merit Network, CYCLADES, Telenet, were developed in the late 1960s and early 1970s using a variety of communications protocols. Donald Davies first demonstrated packet switching in 1967 at the National Physics Laboratory in the UK, which became a testbed for UK research for two decades; the ARPANET project led to the development of protocols for internetworking, in which multiple separate networks could be joined into a network of networks.
The Internet protocol suite was developed by Robert E. Kahn and Vint Cerf in the 1970s and became the standard networking protocol on the ARPANET, incorporating concepts from the French CYCLADES project directed by Louis Pouzin. In the early 1980s the NSF funded the establishment for national supercomputing centers at several universities, provided interconnectivity in 1986 with the NSFNET project, which created network access to the supercomputer sites in the United States from research and education organizations. Commercial Internet service providers began to emerge in the late 1980s; the ARPANET was decommissioned in 1990. Limited private connections to parts of the Internet by commercial entities emerged in several American cities by late 1989 and 1990, the NSFNET was decommissioned in 1995, removing the last restrictions on the use of the Internet to carry commercial traffic. In the 1980s, research at CERN in Switzerland by British computer scientist Tim Berners-Lee resulted in the World Wide Web, linking hypertext documents into an information system, accessible from any node on the network.
Since the mid-1990s, the Internet has had a revolutionary impact on culture and technology, including the rise of near-instant communication by electronic mail, instant messaging, voice over Internet Protocol telephone calls, two-way interactive video calls, the World Wide Web with its discussion forums, social networking, online shopping sites. The research and education community continues to develop and use advanced networks such as JANET in the United Kingdom and Internet2 in the United States. Increasing amounts of data are transmitted at higher and higher speeds over fiber optic networks operating at 1 Gbit/s, 10 Gbit/s, or more; the Internet's takeover of the global communication landscape was instant in historical terms: it only communicated 1% of the information flowing through two-way telecommunications networks in the year 1993 51% by 2000, more than 97% of the telecommunicated information by 2007. Today the Internet continues to grow, driven by greater amounts of online information, commerce and social networking.
However, the future of the global internet may be shaped by regional differences in the world. The concept of data communication – transmitting data between two different places through an electromagnetic medium such as radio or an electric wire – pre-dates the introduction of the first computers; such communication systems were limited to point to point communication between two end devices. Semaphore lines, telegraph systems and telex machines can be considered early precursors of this kind of communication; the Telegraph in the late 19th century was the first digital communication system. Fundamental theoretical work in data transmission and information theory was developed by Claude Shannon, Harry Nyquist, Ralph Hartley in the early 20th century. Early computers had remote terminals; as the technology evolved, new systems were devised to allow communication over longer distances or with higher speed that were necessary for the mainframe computer model. These technologies made it possible to exchange data between remote computers.
However, the point-to-point communication model was limited, as it did not allow for direct communication between any two arbitrary systems. The technology was considered unsafe for strategic and military use because there were no alternative paths for the communication in case of an enemy attack. With limited exceptions, the earliest computers were connected directly to terminals used by individual users in the same building or site; such networks became known as local area networks. Networking beyond this scope, known as wide area networks, emerged during the 1950s and became established during the 1960s. J. C. R. Licklider, Vice President at Bolt Beranek and Newman, Inc. proposed a global network in his January 1960 paper Man-Computer Symbiosis: A network of such centers, connected to one another by wide-band communication lines the functions of present-day libraries together with anticipated advances in information storage and retrieval and symbiotic functions suggested earlier in this paper In August 1962, Licklider and Welden Clark published the paper "On-Line Man-Computer Communication", one of the first descriptions of a networked future.
In October 1962, Licklider was hired by Jack Ruina as director of the newly established Information Processing Techniques Office w
Spacewar! is a space combat video game developed in 1962 by Steve Russell, in collaboration with Martin Graetz and Wayne Wiitanen, programmed by Russell with assistance from others including Bob Saunders and Steve Piner. It was written for the newly installed DEC PDP-1 at the Massachusetts Institute of Technology. After its initial creation, Spacewar was expanded further by other students and employees of universities in the area, including Dan Edwards and Peter Samson, it was spread to many of the few dozen academic, installations of the PDP-1 computer, making Spacewar the first known video game to be played at multiple computer installations. The game features two spaceships, "the needle" and "the wedge", engaged in a dogfight while maneuvering in the gravity well of a star. Both ships are controlled by human players; each ship has limited fuel for maneuvering and a limited number of torpedoes, the ships follow Newtonian physics, remaining in motion when the player is not accelerating. Flying near the star to provide a gravity assist was a common tactic.
Ships are destroyed when hit by a torpedo, colliding with each other. At any time, the player can engage a hyperspace feature to move to a new, random location on the screen, though each use has an increasing chance of destroying the ship instead; the game was controlled with switches on the PDP-1, though Bob Saunders built an early gamepad to reduce the difficulty and awkwardness of controlling the game. Spacewar is one of the most influential games in the early history of video games, it was popular in the small programming community in the 1960s and was ported to other computer systems at the time. It has been recreated in more modern programming languages for PDP-1 emulators, it directly inspired many other electronic games, such as the first commercial arcade video games, Galaxy Game and Computer Space, games such as Asteroids. In 2007, Spacewar was named to a list of the ten most important video games of all time, which formed the start of the game canon at the Library of Congress. During the 1950s, various computer games were created in the context of academic computer and programming research and for demonstrations of computing power after the introduction in the decade of smaller and faster computers on which programs could be created and run in real time as opposed to being executed in batches.
A few programs, while used to showcase the power of the computer they ran on were intended as entertainment products. These interactive graphical games were created by a community of programmers, many of them students and university employees affiliated with the Tech Model Railroad Club led by Alan Kotok, Peter Samson, Bob Saunders; the games included Tic-Tac-Toe, which used a light pen to play a simple game of noughts and crosses against the computer, Mouse in the Maze, which used a light pen to set up a maze of walls for a virtual mouse to traverse. In the fall of 1961, a Digital Equipment Corporation PDP-1 minicomputer was installed in the "kludge room" on the 2nd floor of Building 26, the location of the MIT Electrical Engineering Department; the PDP-1 was to complement the older TX-0, before its arrival a group of students and university employees had been brainstorming ideas for programs that would demonstrate the new computer's capabilities in a compelling way. Three of them—Steve Russell an employee at Harvard University and a former research assistant at MIT.
"We had this brand new PDP-1", Steve Russell told Rolling Stone in a 1972 interview. "Somebody had built some little pattern-generating programs which made interesting patterns like a kaleidoscope. Not a good demonstration. Here was this display that could do all sorts of good things! So we started figuring what would be interesting displays. We decided that you could make a two-dimensional maneuvering sort of thing, decided that the obvious thing to do was spaceships." The gameplay of Spacewar involves two monochrome spaceships called "the needle" and "the wedge", each controlled by a player, attempting to shoot one another while maneuvering on a two-dimensional plane in the gravity well of a star, set against the backdrop of a starfield. The ships fire torpedoes; the ships have a limited number of torpedoes and a limited supply of fuel, used when the player fires his thrusters. Torpedoes are fired one at a time by flipping a toggle switch on the computer or pressing a button on the control pad, there is a cooldown period between launches.
The ships follow Newtonian physics, remaining in motion when the player is not accelerating, though the ships can rotate at a constant rate without inertia. Each player controls one of the ships and must attempt to shoot down the other ship while avoiding a collision with the star or each other. Flying near the star can provide a gravity assist to the player at the risk of misjudging the trajectory and falling into the star. If a ship moves past one edge of the screen, it reappears on the other side in a wraparound ef
IEEE 802.11 is part of the IEEE 802 set of LAN protocols, specifies the set of media access control and physical layer protocols for implementing wireless local area network Wi-Fi computer communication in various frequencies, including but not limited to 2.4, 5, 60 GHz frequency bands. They are the world's most used wireless computer networking standards, used in most home and office networks to allow laptops and smartphones to talk to each other and access the Internet without connecting wires, they are created and maintained by the Institute of Electrical and Electronics Engineers LAN/MAN Standards Committee. The base version of the standard was released in 1997, has had subsequent amendments; the standard and amendments provide the basis for wireless network products using the Wi-Fi brand. While each amendment is revoked when it is incorporated in the latest version of the standard, the corporate world tends to market to the revisions because they concisely denote capabilities of their products.
As a result, in the marketplace, each revision tends to become its own standard. The protocols are used in conjunction with IEEE 802.2, are designed to interwork seamlessly with Ethernet, are often used to carry Internet Protocol traffic. Although IEEE 802.11 specifications list channels that might be used, the radio frequency spectrum availability allowed varies by regulatory domain. The 802.11 family consists of a series of half-duplex over-the-air modulation techniques that use the same basic protocol. The 802.11 protocol family employ carrier-sense multiple access with collision avoidance whereby equipment listens to a channel for other users before transmitting each packet. 802.11-1997 was the first wireless networking standard in the family, but 802.11b was the first accepted one, followed by 802.11a, 802.11g, 802.11n, 802.11ac. Other standards in the family are service amendments that are used to extend the current scope of the existing standard, which may include corrections to a previous specification.802.11b and 802.11g use the 2.4 GHz ISM band, operating in the United States under Part 15 of the U.
S. Federal Communications Commission Rules and Regulations; because of this choice of frequency band, 802.11b/g/n equipment may suffer interference in the 2.4 GHz band from microwave ovens, cordless telephones, Bluetooth devices etc. 802.11b and 802.11g control their interference and susceptibility to interference by using direct-sequence spread spectrum and orthogonal frequency-division multiplexing signaling methods, respectively. 802.11a uses the 5 GHz U-NII band, for much of the world, offers at least 23 non-overlapping 20 MHz-wide channels rather than the 2.4 GHz ISM frequency band offering only three non-overlapping 20 MHz-wide channels, where other adjacent channels overlap—see list of WLAN channels. Better or worse performance with higher or lower frequencies may be realized, depending on the environment. 802.11 n can use either the 5 GHz band. The segment of the radio frequency spectrum used by 802.11 varies between countries. In the US, 802.11a and 802.11g devices may be operated without a license, as allowed in Part 15 of the FCC Rules and Regulations.
Frequencies used by channels one through six of 802.11b and 802.11g fall within the 2.4 GHz amateur radio band. Licensed amateur radio operators may operate 802.11b/g devices under Part 97 of the FCC Rules and Regulations, allowing increased power output but not commercial content or encryption. 802.11 technology has its origins in a 1985 ruling by the U. S. Federal Communications Commission that released the ISM band for unlicensed use. In 1991 NCR Corporation/AT & T invented a precursor to 802.11 in the Netherlands. The inventors intended to use the technology for cashier systems; the first wireless products were brought to the market under the name WaveLAN with raw data rates of 1 Mbit/s and 2 Mbit/s. Vic Hayes, who held the chair of IEEE 802.11 for 10 years, has been called the "father of Wi-Fi", was involved in designing the initial 802.11b and 802.11a standards within the IEEE. In 1999, the Wi-Fi Alliance was formed as a trade association to hold the Wi-Fi trademark under which most products are sold.
The major commercial breakthrough came with Apple Inc. adopting Wi-Fi for their iBook series of laptops in 1999. It was the first mass consumer product to offer Wi-Fi network connectivity, branded by Apple as AirPort. One year IBM followed with its ThinkPad 1300 series in 2000; the original version of the standard IEEE 802.11 was released in 1997 and clarified in 1999, but is now obsolete. It specified two net bit rates of 2 megabits per second, plus forward error correction code, it specified three alternative physical layer technologies: diffuse infrared operating at 1 Mbit/s. The latter two radio technologies used microwave transmission over the Industrial Scientific Medical frequency band at 2.4 GHz. Some earlier WLAN technologies used lower frequencies, such as the U. S. 900 MHz ISM band. Legacy 802.11 with direct-sequence spread spectrum was supplanted and popularized by 802.11b. 802.11a, published in 1999, uses the same data link layer protocol and frame format as the original standard, but an OFDM based air interface.
It operates in the 5 GHz band with a maximum net data rate of 54 Mbit/s, plus error correction code, which yields realistic net achievable throughput in the mid-20
Web search engine
A web search engine or Internet search engine is a software system, designed to carry out web search, which means to search the World Wide Web in a systematic way for particular information specified in a web search query. The search results are presented in a line of results referred to as search engine results pages; the information may be a mix of web pages, videos, articles, research papers and other types of files. Some search engines mine data available in databases or open directories. Unlike web directories, which are maintained only by human editors, search engines maintain real-time information by running an algorithm on a web crawler. Internet content, not capable of being searched by a web search engine is described as the deep web. Internet search engines themselves predate the debut of the Web in December 1990; the Who is user search dates back to 1982 and the Knowbot Information Service multi-network user search was first implemented in 1989. The first well documented search engine that searched content files, namely FTP files was Archie, which debuted on 10 September 1990.
Prior to September 1993, the World Wide Web was indexed by hand. There was a list of webservers hosted on the CERN webserver. One snapshot of the list in 1992 remains, but as more and more web servers went online the central list could no longer keep up. On the NCSA site, new servers were announced under the title "What's New!"The first tool used for searching content on the Internet was Archie. The name stands for "archive" without the "v", it was created by Alan Emtage, Bill Heelan and J. Peter Deutsch, computer science students at McGill University in Montreal, Canada; the program downloaded the directory listings of all the files located on public anonymous FTP sites, creating a searchable database of file names. The rise of Gopher led to two new search programs and Jughead. Like Archie, they searched the file titles stored in Gopher index systems. Veronica provided a keyword search of most Gopher menu titles in the entire Gopher listings. Jughead was a tool for obtaining menu information from specific Gopher servers.
While the name of the search engine "Archie Search Engine" was not a reference to the Archie comic book series, "Veronica" and "Jughead" are characters in the series, thus referencing their predecessor. In the summer of 1993, no search engine existed for the web, though numerous specialized catalogues were maintained by hand. Oscar Nierstrasz at the University of Geneva wrote a series of Perl scripts that periodically mirrored these pages and rewrote them into a standard format; this formed the basis for W3Catalog, the web's first primitive search engine, released on September 2, 1993. In June 1993, Matthew Gray at MIT, produced what was the first web robot, the Perl-based World Wide Web Wanderer, used it to generate an index called'Wandex'; the purpose of the Wanderer was to measure the size of the World Wide Web, which it did until late 1995. The web's second search engine Aliweb appeared in November 1993. Aliweb did not use a web robot, but instead depended on being notified by website administrators of the existence at each site of an index file in a particular format.
JumpStation used a web robot to find web pages and to build its index, used a web form as the interface to its query program. It was thus the first WWW resource-discovery tool to combine the three essential features of a web search engine as described below; because of the limited resources available on the platform it ran on, its indexing and hence searching were limited to the titles and headings found in the web pages the crawler encountered. One of the first "all text" crawler-based search engines was WebCrawler, which came out in 1994. Unlike its predecessors, it allowed users to search for any word in any webpage, which has become the standard for all major search engines since, it was the search engine, known by the public. In 1994, Lycos was launched and became a major commercial endeavor. Soon after, many search engines vied for popularity; these included Magellan, Infoseek, Northern Light, AltaVista. Yahoo! was among the most popular ways for people to find web pages of interest, but its search function operated on its web directory, rather than its full-text copies of web pages.
Information seekers could browse the directory instead of doing a keyword-based search. In 1996, Netscape was looking to give a single search engine an exclusive deal as the featured search engine on Netscape's web browser. There was so much interest that instead Netscape struck deals with five of the major search engines: for $5 million a year, each search engine would be in rotation on the Netscape search engine page; the five engines were Yahoo!, Lycos and Excite. Google adopted the idea of selling search terms in 1998, from a small search engine company named goto.com. This move had a significant effect on the SE business, which went from struggling to one of the most profitable businesses in the Internet. Search engines were known as some of the brightest stars in the Internet investing frenzy that occurred in the late 1990s. Several
History of Unix
The history of Unix dates back to the mid-1960s when the Massachusetts Institute of Technology, AT&T Bell Labs, General Electric were jointly developing an experimental time sharing operating system called Multics for the GE-645 mainframe. Multics had many problems. Bell Labs, frustrated by the size and complexity of Multics but not the aims pulled out of the project, their last researchers to leave Multics, Ken Thompson, Dennis Ritchie, Doug McIlroy, Joe Ossanna among others, decided to redo the work on a much smaller scale. In 1979, Dennis Ritchie described their vision for Unix: What we wanted to preserve was not just a good environment in which to do programming, but a system around which a fellowship could form. We knew from experience that the essence of communal computing, as supplied by remote-access, time-shared machines, is not just to type programs into a terminal instead of a keypunch, but to encourage close communication. In the late 1960s, Bell Labs was involved in a project with MIT and General Electric to develop a time-sharing system, called Multiplexed Information and Computing Service, allowing multiple users to access a mainframe simultaneously.
Dissatisfied with the project's progress, Bell Labs management withdrew. Ken Thompson, a programmer in the Labs' computing research department, had worked on Multics, he decided to write his own operating system. While he still had access to the Multics environment, he wrote simulations for the new file and paging system on it, he programmed a game called Space Travel, but it needed a more efficient and less expensive machine to run on, he found a little-used PDP-7 at Bell Labs. On the PDP-7, in 1969, a team of Bell Labs researchers led by Thompson and Ritchie, including Rudd Canaday, implemented a hierarchical file system, the concepts of computer processes and device files, a command-line interpreter, some small utility programs, modeled on the corresponding features in Multics, but simplified; the resulting system, much smaller and simpler than Multics, was to become Unix. In about a month's time, Thompson had implemented a self-hosting operating system with an assembler and shell, using a GECOS machine for bootstrapping.
The new operating system was without organizational backing, without a name. At this stage, the new operating system was a singletasking operating system, not a multitasking one such as Multics; the name Unics, a pun on Multics, was suggested for the project in 1970. Brian Kernighan claims the coining for himself, adds that "no one can remember" who came up with the final spelling Unix. Dennis Ritchie and Doug McIlroy credit Kernighan. Peter H. Salus says; this statement, however, is just a quotation of Steve Bourne's conjecture, based on the fact Neumann liked puns. Salus did any confirmation; when the Computing Sciences Research Center wanted to use Unix on a machine larger than the PDP-7, while another department needed a word processor and Ritchie added text processing capabilities to Unix and received funding for a PDP-11/20. For the first time in 1970, the Unix operating system was named and ran on the PDP-11/20. A text formatting program called a text editor were added. All three were written in PDP-11/20 assembly language.
Bell Labs used this initial text processing system, consisting of Unix and the editor, for text processing of patent applications. Roff soon evolved into troff, the first electronic publishing program with full typesetting capability; as the system grew in complexity and the research team wanted more users, the need for a manual grew apparent. The UNIX Programmer's Manual was published on 3 November 1971. After other Bell Labs departments purchased PDP-11s, they chose to run Unix instead of DEC's own operating system. By Version 4 it was used within the laboratory and a Unix Support Group was formed, helping the operating system survive by formalizing its distribution. In 1973, Version 4 Unix was rewritten in the higher-level language C, contrary to the general notion at the time that an operating system's complexity and sophistication required it to be written in assembly language; the C language appeared as part of Version 2. Thompson and Ritchie were so influential on early Unix that McIlroy estimated that they wrote and debugged about 100,000 lines of code that year, stating that " may safely be assumed to be attached to everything not otherwise attributed".
Although assembly did not disappear from the man pages until Version 8, the migration to C suggested portability of the software, requiring only a small amount of machine-dependent code to be replaced when porting Unix to other computing platforms. Version 4 Unix, still had many PDP-11 dependent codes, is not suitable for porting; the first port to other platform was made five years for Interdata 8/32. The Unix operating system was first presented formally to the outside world at the 1973 Symposium on Operating Systems Principles, where Ritchie and Thompson delivered a paper; this led to requests for the system, but under a 1956 consent decree in settlement of an antitrust case, the Bell System was forbidden from entering any business other than "common carrier communications services", was req
Bulletin board system
A bulletin board system or BBS is a computer server running software that allows users to connect to the system using a terminal program. Once logged in, the user can perform functions such as uploading and downloading software and data, reading news and bulletins, exchanging messages with other users through public message boards and sometimes via direct chatting. In the middle to late 1980s, message aggregators and bulk store-and-forward'ers sprung up to provide services such as FidoNet, similar to email. Many BBSes offer online games in which users can compete with each other. BBSes with multiple phone lines provide chat rooms, allowing users to interact with each other. Bulletin board systems were in many ways a precursor to the modern form of the World Wide Web, social networks, other aspects of the Internet. Low-cost, high-performance modems drove the use of online services and BBSes through the early 1990s. Infoworld estimated that there were 60,000 BBSes serving 17 million users in the United States alone in 1994, a collective market much larger than major online services such as CompuServe.
The introduction of inexpensive dial-up internet service and the Mosaic web browser offered ease of use and global access that BBS and online systems did not provide, led to a rapid crash in the market starting in 1994. Over the next year, many of the leading BBS software providers went bankrupt and tens of thousands of BBSes disappeared. Today, BBSing survives as a nostalgic hobby in most parts of the world, but it is still an popular form of communication for Taiwanese youth. Most surviving BBSes are accessible over Telnet and offer free email accounts, FTP services, IRC and all the protocols used on the Internet; some offer access through packet switched networks or packet radio connections. A precursor to the public bulletin board system was Community Memory, started in August 1973 in Berkeley, California. Useful microcomputers did not exist at that time, modems were both expensive and slow. Community Memory therefore ran on a mainframe computer and was accessed through terminals located in several San Francisco Bay Area neighborhoods.
The poor quality of the original modem connecting the terminals to the mainframe prompted a user to invent the Pennywhistle modem, whose design was influential in the mid-1970s. Community Memory allowed the user to type messages into a computer terminal after inserting a coin, offered a "pure" bulletin board experience with public messages only, it did offer the ability to tag messages with keywords. The system acted in the form of a buy and sell system with the tags taking the place of the more traditional classifications, but users found ways to express themselves outside these bounds, the system spontaneously created stories and other forms of communications. The system was expensive to operate, when their host machine became unavailable and a new one could not be found, the system closed in January 1975. Similar functionality was available to most mainframe users, which might be considered a sort of ultra-local BBS when used in this fashion. Commercial systems, expressly intended to offer these features to the public, became available in the late 1970s and formed the online service market that lasted into the 1990s.
One influential example was PLATO, which had thousands of users by the late 1970s, many of whom used the messaging and chat room features of the system in the same way that would become common on BBSes. Early modems were very simple devices using acoustic couplers to handle telephone operation; the user would first pick up the phone, dial a number press the handset into rubber cups on the top of the modem. Disconnecting at the end of a call required the user to pick up the handset and return it to the phone. Examples of direct-connecting modems did exist, these allowed the host computer to send it commands to answer or hang up calls, but these were expensive devices used by large banks and similar companies. With the introduction of microcomputers with expansion slots, like the S-100 bus machines and Apple II, it became possible for the modem to communicate instructions and data on separate lines. A number of modems of this sort were available by the late 1970s; this made the BBS possible for the first time, as it allowed software on the computer to pick up an incoming call, communicate with the user, hang up the call when the user logged off.
The first public dial-up BBS was developed by Randy Suess. According to an early interview, when Chicago was snowed under during the Great Blizzard of 1978, the two began preliminary work on the Computerized Bulletin Board System, or CBBS; the system came into existence through a fortuitous combination of Christensen having a spare S-100 bus computer and an early Hayes internal modem, Suess's insistence that the machine be placed at his house in Chicago where it would be a local phone call to millions of users. Christensen patterned the system after the cork board his local computer club used to post information like "need a ride". CBBS went online on 16 February 1978. CBBS, which kept a count of callers connected 253,301 callers before it was retired. A key innovation required for the popularization of the BBS was the Smartmodem manufactured by Hayes Microcomputer Products. Internal modems like the ones used by CBBS and similar early systems were usable, but expensive due to the manufacturer having to make a different modem for every computer platform they wanted to target.
They were limited to those