IBM 3480 Family

The 3480 tape format is a magnetic tape data storage format developed by IBM. The tape is one half inch wide and is packaged in a 4"x5"x1" cartridge. The cartridge contains a single reel; the takeup reel is inside the tape drive.

Because of their speed, reliability, durability and low media cost, these tapes and tape drives are still in high demand. A hallmark of the genre is transferability. Tapes recorded with one tape drive are generally readable on another drive, even if the tape drives were built by different manufacturers.

Tape drives conforming with the IBM 3480 product family specification were manufactured by a variety of vendors from 1984 to 2004. Core manufacturers included IBM, Fujitsu, M4 Data, Overland Data, StorageTek and Victor Data Systems (VDS). Various models of these tape drives were also marketed under other brands, including DEC, MP Tapes, Philips, Plasmon, Qualstar, Tandem, and Xcerta.

IBM designated all versions of 3480 and 3490E tape drives as members of the 3480 Product Family.

Tape drives built for the 3480 were initially designed for IBM System/370 computers. Therefore, the first 3480 tape drives communicated through a bus and tag interface. Later models were able to take advantage of ESCON and high voltage SCSI interfaces. The advent of the SCSI interface made it possible to connect 3480 family tape drives to personal computers, which enabled mainframe-to-PC data exchange.

The first 3480 tape drives were introduced in 1984. The IBM 3480 was the first tape drive to employ thin-film heads and the first to use chromium dioxide tape.

It was also distinguished by a relatively high data transfer rate: 3 megabytes per second. This was because it was able to read and write linear data across 18 recording tracks simultaneously, or 38,000 bytes per inch of tape. IBM's prior technology employed 9 recording tracks with a data density of 6,250 bytes per inch of tape, so the 3480 format was greeted as a major breakthrough. The IBM 3480 cartridge stored 200 megabytes in a modest 4x5 inch cartridge compared to the previous technology's 140 megabytes on a 10.5 inch diameter (2400 foot length) reel of 1/2" tape. The 3480 and its successors are streaming drives. The 3480 was initially a disaster, because it would consistently underrun as the 3 MB/s bus and tag channels and the 3 MB/s drives could not feed the 3MB/s second tape drives because of various interferences such as seeks. The streaming drives would then have to stop, back up and restart, reducing throughput to under 200 KB/s.

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