#@storage@# (Or "magtape", "tape" - paper tape is now obsolete) A data storage medium consisting of a magnetisable oxide coating on a thin plastic strip, commonly used for Early industry-standard magnetic tape was half an inch wide and wound on removable reels 10.5 inches in diameter. Different lengths were available with 2400 feet and 4800 feet In modern magnetic tape systems the reels are much smaller and are fixed inside a cartridge to protect the tape and for rectangular). Cartridge formats include QIC, DAT, and Tape is read and written on a tape drive (or "deck") which winds the tape from one reel to the other causing it to move past a read/write head. Early tape had seven parallel tracks of data along the length of the tape allowing six bit characters plus parity written across the tape. A typical recording density was 556 characters per inch. The tape had reflective marks near its end which signaled beginning of tape (BOT) and end of tape (EOT) to the hardware. between them. Each block is typically written in a single operation with the tape running continuously during the write. The larger the block the larger the data buffer required in order to supply or receive the data written to or read from the tape. The smaller the block the more tape is wasted as inter-block gaps. Several logical records may be combined into one physical block to reduce wastage (" blockedrecords"). Finding a certain block on the tape generally involved reading sequentially from the beginning, in contrast tape marks to be written which can be detected while winding the tape forward or rewinding it at high speed. These are typically used to separate logical files on a tape. There are several algorithms which provide similar results: (1997-04-05)
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