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IBM 7702
The IBM 7701 Magnetic Tape Transmission Terminal was a communications device announced by IBM in 1960. It was designed to transfer the contents of a reel of magnetic tape over a leased or dial telephone circuit. The IBM 7702 was a similar device that could communicate at higher speeds. The 7701 was the first product introduced in conjunction with IBM's ''TELE-PROCESSING'' trademark. Technical details The 7701 communicated using the Synchronous transmit-receive Synchronous transmit-receive (STR) was an early IBM character-oriented communications protocol which preceded Bisync. STR was point-to-point only, and employed a ''four-of-eight'' transmission code, communicating at up to 5100 characters per sec ... (STR) communications protocol over either private or switched (''message service'') telephone lines. It operated at speeds of either 75 or 150 characters per second (cps). The 7702 operated at speeds of either 150, 250, or 300 characters per second. The devices used a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetic Tape Data Storage
Magnetic-tape data storage is a system for storing digital information on magnetic tape using digital recording. Tape was an important medium for primary data storage in early computers, typically using large open reels of IBM 7 track, 7-track, later 9-track tape, 9-track tape. Modern magnetic tape is most commonly packaged in cartridges and cassettes, such as the widely supported Linear Tape-Open (LTO) and IBM 3592 series. The device that performs the writing or reading of data is called a tape drive. Autoloader (data storage device), Autoloaders and tape library, tape libraries are often used to automate cartridge handling and exchange. Compatibility was important to enable transferring data. Tape data storage is now used more for system backup, data archive and data exchange. The low cost of tape has kept it viable for long-term storage and archive. Open reels Initially, magnetic tape for data storage was wound on reels. This standard for large computer systems persis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Synchronous Transmit-receive
Synchronous transmit-receive (STR) was an early IBM character-oriented communications protocol which preceded Bisync. STR was point-to-point only, and employed a ''four-of-eight'' transmission code, communicating at up to 5100 characters per second over half-duplex or full-duplex communication lines. The IBM 1009 Data Transmission Unit, the IBM 1130 Synchronous Communications Adapter, the IBM System/360 model 20 Communications Adapter, and the IBM 2701 Data Transmission Unit provided host computer support for STR. The IBM 7701, the IBM 7702 Magnetic Tape Transmission Terminal, the IBM 1013 Card Transmission Terminal, and the IBM 7710 and IBM 7711 Data Communication Units were among the remote devices supported by STR. STR was still supported as of 1972, although it had generally faded from use. Four-of-eight code The four-of-eight code was a 64 character set plus six control characters, encoded in eight bits. Like other kinds of 6b/8b encoding, exactly four bits of each ch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
BCD (6-bit)
BCD (''binary-coded decimal''), also called alphanumeric BCD, alphameric BCD, BCD Interchange Code, or BCDIC, is a family of representations of numerals, uppercase Latin letters, and some special and control characters as six-bit character codes. Unlike later encodings such as ASCII, BCD codes were not standardized. Different computer manufacturers, and even different product lines from the same manufacturer, often had their own variants, and sometimes included unique characters. Other six-bit encodings with completely different mappings, such as some FIELDATA variants or Transcode, are sometimes incorrectly termed BCD. Many variants of BCD encode the characters '0' through '9' as the corresponding binary values. History Technically, '' binary-coded decimal'' describes the encoding of decimal numbers where each decimal digit is represented by a fixed number of bits, usually four. With the introduction of the ''IBM card'' in 1928, IBM created a code capable of representing a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
