IEEE Computer: Alan Turing at Bletchley Park. Internet Pioneers: Dr. Larry Smarr - How the Internet Happened. ARPANET Maps. IBM 3270. The IBM 3270 is a class of block oriented computer terminal (sometimes called display devices) made by IBM originally introduced in 1971[1] normally used to communicate with IBM mainframes.
The 3270 was the successor to the IBM 2260 display terminal. Due to the text colour on the original models, these terminals are informally known as green screen terminals. Unlike a character-oriented terminal, the 3270 minimizes the number of I/O interrupts required by transferring large blocks of data known as data streams, and uses a high speed proprietary communications interface, using coaxial cable. Although IBM no longer manufactures 3270 terminals, the IBM 3270 protocol is still commonly used via terminal emulation to access some mainframe-based applications.
Accordingly, such applications are sometimes referred to as green screen applications. IBM 3277 Display Terminal model 2, the "original" 3270 (1972) IBM 3279 Colour Display Terminal (1979) Principles[edit] Applications[edit] Models[edit] BITNET. BITNET was a cooperative USA university computer network founded in 1981 by Ira Fuchs at the City University of New York (CUNY) and Greydon Freeman at Yale University.[1] The first network link was between CUNY and Yale.
The requirements for a college or university to join BITNET were simple: Lease a data circuit (phone line) from a site to an existing BITNET node.Buy modems for each end of the data circuit, sending one to the connecting point site.Allow other institutions to connect to a site without chargeback. BITNET came to mean "Because It's Time Network", although the original meaning was "Because It's There Network".[2] At its zenith around 1991, BITNET extended to almost 500 organizations and 3,000 nodes, all educational institutions. It spanned North America (in Canada it was known as NetNorth), Europe (as EARN), Israel (as ISRAEARN), India (TIFR) and some Persian Gulf states (as GulfNet). In 1996, CREN ended their support for BITNET. See also[edit] References[edit] Leased line. A leased line is a service contract between a provider and a customer, whereby the provider agrees to deliver a symmetric telecommunications line connecting two or more locations in exchange for a monthly rent (hence the term lease).
It is sometimes known as a "private circuit" or "data line" in the UK. Unlike traditional PSTN lines it does not have a telephone number, each side of the line being permanently connected to the other. Leased lines can be used for telephone, data or Internet services. Some are ringdown services, and some connect to PBXes. Typically, leased lines are used by businesses to connect geographically distant offices. An Internet leased line is a premium internet connectivity product, delivered over fiber normally, which is dedicated and provides uncontended, symmetrical speeds, full-duplex.
For example, a T-1 channel can be leased, and provides a maximum transmission speed of 1.544 Mbit/s. History[edit] Applications[edit] Site to site data connectivity[edit]