Carousel memory

Carousel memory Facit ECM 64 from Facit (2010)
Carousel memory for SMIL, now at the "Teknikens och sjöfartens hus" in Malmö, Sweden (2013)

Carousel memory is a type of secondary storage for computers, which was created by Swedish computer engineers Erik Stemme and Gunnar Stenudd.[1] It was first shown at an exhibition in Paris in 1958.[2]

Facit ECM 64 description

The FACIT ECM 64, manufactured by Swedish company Facit AB, employed a similar technique to avoid the use of a single, long magnetic tape. Instead, it used 64 small rolls with 9 meters each,with 1.6 cm wide tape on each roll, divided into 8 channels per roll.[3] The tape speed is 5 m/s.[3] To read a specific roll, the carousel was rotated such that the desired roll ended up at the bottom. A weight in the free end of the tape pulled it out and down inside a mechanism with a read and write head. After this it was quickly re-winded back. The average seek time was 2 seconds[3] and the storage space was 2560 kilobytes.[4] The control system was completely transistorized. Both the carousel and individual spools could be replaced.[1]

The magnetic tape used was 5/8 inch (1.6 cm) wide, 0.05 mm thick Mylar 3M Co type 188.[3] The storage density is specified to 8 bits/mm[3] and the access head had the capability for simultaneous read- and write operation.[3] The power inlet requirement is 3-phase 380 volt 50 Hz and needed 300 W in standby and 750 W when active. Signaling for data used 8 parallel -20 V to 0 V 5 µs pulses.[3]

Peak transfer speed was 182 044 bits/s[3][4] using 8-parallel lines[3] and thus 22 756 bits/s per line.

The first delivery of the Facit EDB 3 computer in 1958 (to ASEA in Västerås) used the carousel memory Facit ECM 64.[5]

See also

Further reading

References

  1. 1 2 Pär Rittsel (2002), Valsen inledde skivans historia [The roll initiated the disc history] (in Swedish), International Data Group (published 2010-09-11), retrieved 2016-03-22, Även om datorerna blev få så blev Erik Stemmes och Gunnar Stenudds karusellminne, stans och läsare för hålremsor stora (HTML 26 kB)
  2. ↑ Magnetband till karusellminne, Föremål [Magnetic tape for carousel memory, Object] (in Swedish), Kringla, Riksantikvarieämbetet, retrieved 2016-03-22, Karusellminnet Facit ECM 64 visades första gången på en utställning i Paris 1958. Serietillverkades åren 1959-1964. (HTML 67 kB)
  3. 1 2 3 4 5 6 7 8 9 FACIT electronics AB (1961), TPU 610301 FACIT ECM 64 Karusellminne, Preliminär teknisk beskrivning [TPU 610301 FACIT ECM 64 Carousel memory, preliminary technical description] (PDF) (in Swedish), Swedish National Museum of Science and Technology (published 2012-06-15), pp. 3– (2936 kB)
  4. 1 2 FACIT electronics AB (1963), Facit Electronic presenterar FACIT ECM 64 Magnetbandsminne av karuselltyp med direkt access [Facit Electronics presents FACIT ECM 64 Magnetic tape memory of carousel type with direct access] (PDF) (in Swedish), Swedish National Museum of Science and Technology (published 2012-06-15) (2581 kB)
  5. ↑ Göran Arvidsson (2002), FACIT i den tidiga dataåldern [FACIT in the early computer age] (PDF) (in Swedish) (published 2015-08-23), p. 3 (682 kB)
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