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BiSync
Binary Synchronous Communication (BSC or Bisync) is an IBM character-oriented, half-duplex link protocol, announced in 1967 after the introduction of System/360. It replaced the synchronous transmit-receive (STR) protocol used with second generation computers. The intent was that common link management rules could be used with three different character encodings for messages. Six-bit Transcode looked backwards to older systems; USASCII with 128 characters and EBCDIC with 256 characters looked forward. Transcode disappeared very quickly but the EBCDIC and USASCII dialects of Bisync continued in use. At one time Bisync was the most widely used communications protocol and is still in limited use in 2013. Framing Bisync differs from protocols that succeeded it in the complexity of message framing. Later protocols use a single framing scheme for all messages sent by the protocol. HDLC, Digital Data Communications Message Protocol (DDCMP), Point-to-Point Protocol (PPP), etc. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IBM 3780
The IBM 2780 and the IBM 3780 are devices developed by IBM to perform remote job entry (RJE) and other batch functions over telephone lines; they communicate with the mainframe via Binary Synchronous Communications (BSC or Bisync) and replaced older terminals using synchronous transmit-receive (STR). In addition, IBM has developed workstation programs for the 1130, 360/20, 2922, System/360 other than 360/20, System/370 and System/3. 2780 Data Transmission Terminals The 2780 Data Transmission Terminal first shipped in 1967. It consists of: * A line printer similar to the IBM 1443 that can print up to 240 lines per minute (lpm), or 300 lpm using an extremely restricted character set. * A card reader/punch unit, similar to an IBM 1442, that can read up to 400 cards per minute (cpm) and can punch up to 355 cpm. * A line buffer that stores data received or to be transmitted over the communications line. * A binary synchronous adapter which controls the flow of data ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IBM 2780
The IBM 2780 and the IBM 3780 are devices developed by IBM to perform remote job entry (RJE) and other batch functions over telephone lines; they communicate with the mainframe via Binary Synchronous Communications (BSC or Bisync) and replaced older terminals using synchronous transmit-receive (STR). In addition, IBM has developed workstation programs for the 1130, 360/20, 2922, System/360 other than 360/20, System/370 and System/3. 2780 Data Transmission Terminals The 2780 Data Transmission Terminal first shipped in 1967. It consists of: * A line printer similar to the IBM 1443 that can print up to 240 lines per minute (lpm), or 300 lpm using an extremely restricted character set. * A card reader/punch unit, similar to an IBM 1442, that can read up to 400 cards per minute (cpm) and can punch up to 355 cpm. * A line buffer that stores data received or to be transmitted over the communications line. * A binary synchronous adapter which controls the flow of data ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sync Word
In computer networks, a syncword, sync character, sync sequence or preamble is used to synchronize a data transmission by indicating the end of header information and the start of data. The syncword is a known sequence of data used to identify the start of a frame, and is also called ''reference signal'' or ''midamble'' in wireless communications. Prefix codes allow unambiguous identification of synchronization sequences and may serve as self-synchronizing code. Examples In an audio receiver receiving a bit stream of data, an example of a syncword is 0x0B77 for an AC-3 encoded stream. An Ethernet packet with the Ethernet preamble, 56 bits of alternating 1 and 0 bits, allowing the receiver to synchronize its clock to the transmitter, followed by a one-octet start frame delimiter byte and then the header. All USB packets begin with a sync field (8 bits long at low speed, 32 bits long at high speed) used to synchronize the receiver's clock to the transmitter's clock. A r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Negative-acknowledge Character
In data networking, telecommunications, and computer buses, an acknowledgment (ACK) is a signal that is passed between communicating processes, computers, or devices to signify acknowledgment, or receipt of message, as part of a communications protocol. The negative-acknowledgement (NAK or NACK) is a signal that is sent to reject a previously received message or to indicate some kind of error. Acknowledgments and negative acknowledgments inform a sender of the receiver's state so that it can adjust its own state accordingly. Many protocols contain checksums to verify the integrity of the payload and header. Checksums are used to detect data corruption. If a message is received with an invalid checksum (that is, the data received would have a different checksum than the message had), the receiver can know that some information was corrupted. Most often, when checksums are employed, a corrupted message received will either not be served an ACK signal, or will be served a NAK signa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
VTAM
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] |
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 Suppor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
QTAM
Queued Telecommunications Access Method (QTAM) is an IBM System/360 communications access method incorporating built-in queuing. QTAM was an alternative to the lower level Basic Telecommunications Access Method (BTAM). History QTAM was announced by IBM in 1965 as part of OS/360 and DOS/360 aimed at inquiry and data collection. As announced it also supported remote job entry (RJE) applications, called ''job processing'', which was dropped by 1968. Originally QTAM supported the IBM 1030 Data Collection System, IBM 1050 Data Communications System, the IBM 1060 Data Communications System, the IBM 2671 Paper Tape Reader, AT&T 83B2 Selective Calling Stations, Western Union Plan 115A Outstations, and AT&T Teletype Model 33 or 35 Teletypewriters. By 1968 terminal support had expanded to include the IBM 2260 display complex, and the IBM 2740 communications terminal. QTAM devices were attached to a System/360 multiplexor channel through an IBM 2701 Data Adapter or IBM 2702 Trans ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Access Methods
An access method is a function of a mainframe operating system that enables access to data on disk, tape or other external devices. Access methods were present in several mainframe operating systems since the late 1950s, under a variety of names; the name ''access method'' was introduced in 1963 in the IBM OS/360 operating system.M. A. Auslander, D. C. Larkin, A. L. Scherr: "The Evolution of the MVS Operating System", pages 478-479 Access methods provide an application programming interface (API) for programmers to transfer data to or from device, and could be compared to |
Mohawk Data Sciences
Mohawk Data Sciences Corporation (MDS) was an early computer hardware company, started by former Univac engineers in 1964; by 1985 they were struggling to sell-off part of their company. History The company was founded in Herkimer, New York, by George Cogar, Lauren King, and Ted Robinson, former Univac employees. Their success in selling their first product, a Key-to-Tape Data Entry device that allowed doing away with Keypunch devices, brought them enough cash to also grow via acquisition. Among their acquisitions was Atron Corporation, developer of a minicomputer, the Atron 501 and 502. From the know-how acquired and absorbed, Mohawk expanded into the areas of controlling line printers and also Remote Job Entry (RJE). This was the basis of their MDS 2400 RJE product, which supported 2780 and HASP. Financial difficulties a decade-and-a-half after the company opened led to the company's restructuring, renaming and eventual takeover. By that time, headquarters had been in Pa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
