Editing CompuServe (section)

===Technology===
The original 1969 dial-up technology was fairly simple—the local telephone number in Cleveland, for example, was a line connected to a [[time-division multiplexer]] that connected via a [[leased line]] to a matched multiplexer in Columbus that was connected to a time-sharing host system. In the earliest buildups, each line terminated at a single machine of CompuServe's host service, so that one dialed different telephone numbers to reach different computers.

Later, the central multiplexers in Columbus were replaced with [[PDP-8]] minicomputers, and the PDP-8s were connected to a DEC [[PDP-15]] minicomputer that acted as switches so a telephone number was not tied to a particular destination host. Finally, in 1977, CompuServe developed its own [[packet switching]] network, implemented by DEC [[PDP-11]] minicomputers acting as network nodes that were installed throughout the United States (and later, in other countries) and interconnected. Over time, the CompuServe network evolved into a complicated multi-tiered network incorporating [[Asynchronous Transfer Mode]] (ATM), [[Frame Relay]] (FR), [[Internet Protocol]] (IP) and [[X.25]] technologies.

In 1981, ''[[The Times]]'' explained CompuServe's technology in one sentence:
<blockquote>
CompuServe is offering a video-text-like service permitting personal computer users to retrieve software from the mainframe computer over telephone lines.<ref>The Times: ''Fireside access to sum of human knowledge'', 24 Feb. 1981, pg. 15</ref>
</blockquote>

''The New York Times'' described them as "the most international of the Big Three" and noted that "it can be reached by a local phone call in more than 700 cities".<ref name=CIS1.NYT/>

CompuServe was also a vendor of other commercial services. One of these was the Financial Services group, which collected and consolidated financial data from myriad data feeds, including [[CompuStat]], Disclosure, [[I/B/E/S]] as well as the price and quote feeds from the major exchanges. CompuServe developed extensive screening and reporting programs that were used by many investment banks on [[Wall Street]].