Carousel memory is a type of

secondary storage Computer data storage is a technology consisting of computer components and recording media that are used to retain digital data. It is a core function and fundamental component of computers. The central processing unit (CPU) of a computer ...

for computers, which was created by

Swedish Swedish or ' may refer to: Anything from or related to Sweden, a country in Northern Europe. Or, specifically: * Swedish language, a North Germanic language spoken primarily in Sweden and Finland ** Swedish alphabet, the official alphabet used by ...

computer engineers and Gunnar Stenudd. It was first shown at an exhibition in

Paris Paris () is the capital and most populous city of France, with an estimated population of 2,165,423 residents in 2019 in an area of more than 105 km² (41 sq mi), making it the 30th most densely populated city in the world in 2020. S ...

in 1958.

Description

The FACIT ECM 64, manufactured by Swedish company Facit AB, is a prototype of carousel memory. To avoid having a single, long

magnetic tape Magnetic tape is a medium for magnetic storage made of a thin, magnetizable coating on a long, narrow strip of plastic film. It was developed in Germany in 1928, based on the earlier magnetic wire recording from Denmark. Devices that use magne ...

, it instead has 64 small rolls of each, with wide tape on each roll, divided into per roll. The tape speed is . To read a particular roll, the carousel rotates so the desired roll ends up at the bottom. A counterweight sits at the free end of the tape, and facilitates the roll in moving out and down into a mechanism with a read-and-write head. The tape is then rewound. The average seek time is and the storage space is . The control system is operated by

transistor upright=1.4, gate (G), body (B), source (S) and drain (D) terminals. The gate is separated from the body by an insulating layer (pink). A transistor is a semiconductor device used to Electronic amplifier, amplify or electronic switch, switch e ...

s. Both the carousel and individual spools are replaceable. The magnetic tape is a 5/8-inch (1.6 cm) wide and 0.05 mm thick

Mylar BoPET (biaxially-oriented polyethylene terephthalate) is a polyester film made from stretched polyethylene terephthalate (PET) and is used for its high tensile strength, chemical and dimensional stability, transparency, reflectivity, gas and aro ...

3M Co type 188.The storage density is specified to , and the access head is capable of simultaneous read/write operations. The power requirement is 3-phase 380 volts 50 Hz, with when in standby and when active. Signaling for data uses -20 V to 0 V 5 µs pulses. Peak transfer speed is , using 8-parallel lines and thus per line. The first delivery of the Facit EDB 3 computer in 1958 (to

ASEA ''Allmänna Svenska Elektriska Aktiebolaget'' (English translation: General Swedish Electrical Limited Company; Swedish abbreviation: ASEA) was a Swedish industrial company. History ASEA was founded in 1883 by Ludvig Fredholm in Västerås as ...

Västerås Västerås ( , , ) is a city in central Sweden on the shore of Mälaren, Lake Mälaren in the province of Västmanland, west of Stockholm. The city had a population of 127,799 at the end of 2019, out of the municipal total of 154,049. Västerås ...

) used the carousel memory Facit ECM 64.

Description

See also

References

Further reading