"Hugo Cornwall "The Hacker's handbook"" - читать интересную книгу автораcould only watch, and 'interrogation' consisted of back-tracking
along a tape of paper. Extel (Exchange Telegraph) continues to use this technique, though it is gradually upgrading by using viewdata and intelligent terminals. However, just over ten years ago Reuters put together the first packages which gave some intelligence and 'questioning power' to the end user. Each Reuters' Monitor is intelligent, containing (usually) a DEC PDP-8 series mini and some firmware which accepts and selects the stream of data from the host at the far end of the leased line, marshalls interrogation requests and takes care of the local display. Information is formatted in 'pages' rather like viewdata frames, but without the colour. There is little point in eavesdropping into a Reuters line unless you know what the terminal firmware does. Reuters now face an aggressive rival in Telerate, and the fight is on to deliver not only fast comprehensive prices services but international screen-based dealing as well. The growth of Reuters and its rivals is an illustration of technology creating markets--especially in international currency--where none existed before. The first sophisticated Stock Exchange prices 'screens' used modified closed circuit television technology. London had a system called Market Price Display Service--MPDS--which consisted of a number of tv displays of current prices services on different 'channels' which could be selected by the user. But London now uses TOPIC, a leased line variant on viewdata technology, though with its magazine-like arrangement and auto-screen refresh, it has as much in total 7,500 shares traded in London, plus selected analytical material from brokers. Datastream represents a much higher level of sophistication: using its г40,000 plus pa terminals you can compare historic data-- price movements, movements against sector indices etc--and chart the results. The hacker's reward for getting into such systems is that you can see share and other prices on the move. None of these prices is confidential; all could be obtained by ringing a stockbroker. However, this situation is likely to change; as the City makes the change from the traditional broker/jobber method of dealing towards specialist market making, there will then be electronic prices services giving privileged information to specialist share dealers. All these services are only available via leased lines; City professionals would not tolerate the delays and uncertainties of dial-up facilities. However dial-up ports exist for demonstrations, exhibitions, engineering and as back-up--and a lot of hacking effort has gone into tracking them down. In the United States, in addition to Reuters, Telerate and local equivalents of official streams of stock exchange and over-the- counter data, there is Dow Jones, best known internationally for its market indices similar to those produced by the Financial Times in London. Dow Jones is in fact the owner of the Wall Street Journal and some influential business magazines. Its Dow Jones News/Retrieval Service is aimed at businesses and private investors. It features |
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