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IBM Network Control Program
The IBM Network Control Program, or NCP, was software that ran on a 37xx communications controller and managed communication with remote devices. NCP provided services comparable to the data link layer and Network Layer functions in the OSI model of a Wide area network. Overview The original IBM Network Control Program ran on the 3705-I and supported access to older devices by application programs using Telecommunications Access Method (TCAM). With the advent of Systems Network Architecture (SNA), NCP was enhanced to connect cluster controllers (such as the IBM 3270) to application programs using TCAM and later to application programs using Virtual Telecommunications Access Method (VTAM). Subsequent versions of NCP were released to run on the IBM 3704, IBM 3705-II, IBM 3725. IBM 3720, or IBM 3745 Communications Controllers, all of which SNA defined as a SNA Physical Unit Type 4 (PU4). A PU4 usually had SDLC links to remote cluster controllers (PU1/PU2) or to other PU4s. Po ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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ARPANET
The Advanced Research Projects Agency Network (ARPANET) was the first wide-area packet-switched network with distributed control and one of the first networks to implement the TCP/IP protocol suite. Both technologies became the technical foundation of the Internet. The ARPANET was established by the Advanced Research Projects Agency (ARPA) of the United States Department of Defense. Building on the ideas of J. C. R. Licklider, Robert Taylor (computer scientist), Bob Taylor initiated the ARPANET project in 1966 to enable access to remote computers. Taylor appointed Lawrence Roberts (scientist), Larry Roberts as program manager. Roberts made the key decisions about the network design. He incorporated Donald Davies' concepts and designs for packet switching, and sought input from Paul Baran. ARPA awarded the contract to build the network to Bolt Beranek & Newman who developed the first Communication protocol, protocol for the network. Roberts engaged Leonard Kleinrock at Universi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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IBM 3270
The IBM 3270 is a family of block oriented display and printer computer terminals introduced by IBM in 1971 and normally used to communicate with IBM mainframes. The 3270 was the successor to the IBM 2260 display terminal. Due to the text color 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. IBM no longer manufactures 3270 terminals, but the IBM 3270 protocol is still commonly used via TN3270 clients, 3270 terminal emulation or web interfaces to access mainframe-based applications, which are sometimes referred to as ''green screen applications''. Principles The 3270 series was designed to connect with mainframe computers, often at a remote location, using the technology then available in the ea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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I/O Channel
In computing, channel I/O is a high-performance input/output (I/O) architecture that is implemented in various forms on a number of computer architectures, especially on mainframe computers. In the past, channels were generally implemented with custom devices, variously named channel, I/O processor, I/O controller, I/O synchronizer, or '' DMA controller''. Overview Many I/O tasks can be complex and require logic to be applied to the data to convert formats and other similar duties. In these situations, the simplest solution is to ask the CPU to handle the logic, but because I/O devices are relatively slow, a CPU could waste time (in computer perspective) waiting for the data from the device. This situation is called 'I/O bound'. Channel architecture avoids this problem by processing some or all of the I/O task without the aid of the CPU by offloading the work to dedicated logic. Channels are logically self-contained, with sufficient logic and working storage to handle I/O tasks. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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System/370
The IBM System/370 (S/370) is a model range of IBM mainframe computers announced on June 30, 1970, as the successors to the System/360 family. The series mostly maintains backward compatibility with the S/360, allowing an easy migration path for customers; this, plus improved performance, were the dominant themes of the product announcement. In September 1990, the System/370 line was replaced with the System/390. Evolution The original System/370 line was announced on June 30, 1970, with first customer shipment of the Models 155 and 165 planned for February 1971 and April 1971 respectively. The 155 first shipped in January 1971. System/370 underwent several architectural improvements during its roughly 20-year lifetime. The following features mentioned in Principles of Operation are either optional on S/360 but standard on S/370, introduced with S/370 or added to S/370 after announcement. *Branch and Save *Channel Indirect Data Addressing *Channel-Set Switching *Clear I/O *C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Communications Controller For Linux
Communications Controller for Linux (Communications Controller for Linux on System z or CCL) is an IBM software product announced in 2005 that runs under Linux on IBM Z and emulates an IBM 37xx communications controller. CCL runs unmodified IBM Network Control Program (NCP) to allow consolidation of an SNA network infrastructure to IP. According to IBM "SNA traffic enters and leaves CCL as SNA network flows over an OSA adapter. However, your wide area network infrastructure does not need to be SNA. You can consolidate your SNA traffic and use tunneling such as data link switching (DLSw) to encapsulate the SNA communication over an IP network." CCL supports Ethernet and Token Ring local area network A local area network (LAN) is a computer network that interconnects computers within a limited area such as a residence, school, laboratory, university campus or office building. By contrast, a wide area network (WAN) not only covers a larger ... (LAN) connectivity directly, an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Synchronous Data Link Control
Synchronous Data Link Control (SDLC) is a computer communications protocol. It is the layer 2 protocol for IBM's Systems Network Architecture (SNA). SDLC supports multipoint links as well as error correction. It also runs under the assumption that an SNA header is present after the SDLC header. SDLC was mainly used by IBM mainframe and midrange systems; however, implementations exist on many platforms from many vendors. In the United States and Canada, SDLC can be found in traffic control cabinets. In 1975, IBM developed the first bit-oriented protocol, SDLC,PC Lube and Tune accessed 15. October 2009. from work done for IBM in the early 1970s.. This |
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IBM 3745
The IBM 3745 is the latest and last of a 37xx family of communications controllers for the IBM mainframe environment. As of mid-2009 there were an estimated 7,000+ of the larger 3745 models still in active production status, down from 20,000 or more in 2007. The 3745 and associated 3746 models were once heavily used within financial, insurance and retail industries as well as within government agencies globally. However, today most organizations have migrated away from the use of 3745s. IBM's Enterprise Extender and the Communication Controller for Linux on System z (CCL) have largely displaced the older 3745s. IBM announced in September 2002 that it would no longer manufacture new 3745s, but IBM continues to support the hardware by providing worldwide maintenance service, by providing microcode releases and by supporting the associated software including NCP (Network Control Program) and the virtual telecommunications access method (VTAM). IBM has announced end-of-servic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Virtual Telecommunications Access Method
Virtual Telecommunications Access Method (VTAM) is the IBM subsystem that implements Systems Network Architecture (SNA) for mainframe environments. VTAM provides an application programming interface (API) for communication applications, and controls communication equipment such as adapters and controllers. In modern terminology, VTAM provides a communication stack and device drivers. History VTAM was introduced in 1974 after a series of delays as a major component of SNA along with the 370x Network Control Program (NCP) and Synchronous Data Link Control (SDLC). In IBM terminology, VTAM is an access method software allowing application programs to read and write data to and from external devices. It is called 'virtual' because it was introduced at the time when IBM was introducing virtual storage by upgrading the operating systems of the System/360 series to virtual storage versions. VTAM was supposed to be the successor to the older telecommunications access methods, such ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Systems Network Architecture
Systems Network Architecture (SNA) is IBM's proprietary networking architecture, created in 1974. It is a complete protocol stack for interconnecting computers and their resources. SNA describes formats and protocols but, in itself, is not a piece of software. The implementation of SNA takes the form of various communications packages, most notably Virtual Telecommunications Access Method (VTAM), the mainframe software package for SNA communications. History SNA was made public as part of IBM's "Advanced Function for Communications" announcement in September, 1974, which included the implementation of the SNA/SDLC (Synchronous Data Link Control) protocols on new communications products: *IBM 3767 communication terminal (printer) *IBM 3770 data communication system They were supported by IBM 3704/3705 communication controllers and their Network Control Program (NCP), and by System/370 and their VTAM and other software such as CICS and IMS. This announcement was followed by ano ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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IBM 37xx
IBM 37xx (or 37x5) is a family of IBM Systems Network Architecture (SNA) programmable communications controllers used mainly in mainframe computer, mainframe environments. All members of the family ran one of three IBM-supplied programs. *''Emulation Program'' (EP) mimicked the operation of the older IBM 270x non-programmable controllers. *''IBM Network Control Program, Network Control Program'' (NCP) supported Systems Network Architecture devices. *''Partitioned Emulation Program'' (PEP) combined the functions of the two. Models 370x series * IBM 3705, 3705 — the oldest of the family, introduced in 1972 to replace the non programmable IBM 270x family. The 3705 could control up to 352 communications lines. * 3704 was a smaller version, introduced in 1973. It supported up to 32 lines. 371x The 3710 communications controller was introduced in 1984. 372x series The 3725 and the 3720 systems were announced in 1983. The 3725 replaced the hardware line scanners used o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Telecommunications Access Method
Telecommunications Access Method (TCAM) is an access method, in IBM's OS/360 and successors computer operating systems on IBM System/360 and later, that provides access to terminals units within a teleprocessing network. Features TCAM provides similar functionality to QTAM, which it replaced. It was the access method for the initial version of Time Sharing Option (TSO). With the advent of IBM's SNA, TCAM was eventually superseded by VTAM. TCAM was said to have the following enhancements over QTAM: * Improved buffering, with more buffering options. * Improved organization of message queuing on disk including multiple volume support. * Back-up copies of messages maintained on disk. * Improved testing and debugging including off-line testing, improved debugging, online terminal testing, and logging. * Improved line handling for inquiry applications. * "Significantly increases speed and efficiency over QTAM." * Improved operator monitoring and control. * Binary Synchronous Support ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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IBM 3705
The IBM 3705 Communications Controller is a simple computer which attaches to an IBM System/360 or System/370. Its purpose is to connect communication lines to the mainframe channel. It was a first communications controller of the popular IBM 37xx series. It was announced in March 1972. Designed for semiconductor memory which was not ready at the time of announcement, the 3705-I had to use 1.2 microsecond core storage; the later 3705-II uses 1.0 microsecond SRAM. Solid Logic Technology components, similar to those in S/370, were used. The 3705 normally occupies a single frame two feet wide and three feet deep. Up to three expansion frames can be attached for a theoretical capacity of 352 half-duplex lines and two independent channel adapters. The 3704 is an entry level version of the 3705 with limited features. Purpose IBM intended it to be used in three ways: # Emulation of the older IBM 2703 Communications Controller and its predecessors. The relevant software is the ''Emulat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |