Magnetic Tape

 
 

10.5" tape

7" tape

9-track tapes, 1/2", 6250bpi. At 6250bpi, a 2400 foot tape like the one on the left can hold about 170MB. The latch on the plastic protective cover is also used to hang tapes from a rack. The cover is removed before mounting the tape. 9-track tapes were in use from the mid-1960s through the 1990s, when cartridge tapes became popular. These particular tapes were used with HP3000 systems, circa 1987.

 
 

DECtape in case

DECtape and case

DECtape

DECtape was introduced in 1963 by Digital Equipment Corporation, and was used on many of their PDP series computers, from the PDP-6 to the PDP-15. The tape was 3/4" wide, with a 3-7/8" diameter reel, and was formatted into blocks. A tape could hold 184K 12-bit words, or 144K 18-bit words. Date was written redundantly across the tape, so data reliability was high.

 
 

DC600A Cartridge tape

QIC 24 (Quarter Inch Cartridge) DC600A cartridge tape, 60MB capacity. The tape is written in 9 tracks, in linear serpentine format. Measures 5-7/8" x 3-7/8" x 5/8". Circa 1983.

 
 

DC6150 Cartridge tape

QIC 150 (Quarter Inch Cartridge) DC6150 cartridge tape, 150MB capacity. The tape is written in 15 tracks, in linear serpentine format. Measures 5-7/8" x 3-7/8" x 5/8". Circa 1991.

 
 

DDS2 tape cartridge

DDS2 (Digital Data Storage) tape cartridge, 2GB native capacity or 4GB compressed, introduced in 1993. The tape is 3.81mm wide, and is written in a helical scan format. The cartridge measures 73mm by 54mm by 10.5mm.

 
 

DLT IV tape cartridge

DLT (Digital Linear Tape) IV tape cartridge, either 20GB, 35GB or 40GB capacity, depending on which tape drive is used (DLT4000/DLT7000/DLT8000). introduced in 1994. The tape is 1/2" wide, and is written in a linear serpentine recording format. The cartridge measures 105.79mm by 105.41mm by 25.40mm.

 
 

IBM 3850 tape cartridge

In 1974, IBM introduced the 3850 MSS (Mass Storage System), which used a number of small cartridges (1-7/8"x3-1/2") to store data. Each cartridge held 770 inches of 2-3/4" wide magnetic tape which would store 50MB of data. Two such cartridges would hold the image of an entire 3336 disk pack. The cartridges were stored in a honeycomb array, and a robotic mechanism was used to load and unload the cartridges. Columbia University has a page with pictures and information for the 3850.

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Last updated on Sunday, September 20, 2009