Carousel memory
Carousel memory is a type of secondary storage for computers, which was created by Swedish computer engineers Erik Stemme (sv) and Gunnar Stenudd.[1] It was first shown at an exhibition in Paris in 1958.[2]
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, it instead has 64 small rolls of 9 meters each, with 1.6-cm wide tape on each roll, divided into eight channels per roll.[3]: 3 The tape speed is 5 m/s.[3]: 6 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 2 seconds[3]: 11 and the storage space is 2560 kilobytes.[4] The control system is operated by transistors. Both the carousel and individual spools are replaceable.[1]
The magnetic tape is a 5/8-inch (1.6 cm) wide and 0.05 mm thick Mylar 3M Co type 188.[3]: 11 The storage density is specified to 8 bits/mm,[3]: 4 and the access head is capable of simultaneous read/write operations.[3]: 3 The power requirement is three-phase 380 volts 50 Hz with 300 W when in standby and 750 W when active. Signaling for data uses eight parallel -20 V to 0 V 5 μs pulses.[3]: 13
Peak transfer speed is 182,044 bits/s,[3][4] using eight parallel lines[3]: 13 and thus 22,756 bits/s per line.
The first delivery of the Facit EDB 3 computer was in 1958 (to ASEA in Västerås) used the carousel memory Facit ECM 64.[5]
See also
- BESK, Sweden's first electronic computer, also developed by Erik Stemme
- Exatron Stringy Floppy, 1978 endless tape drive
- IBM 2321 Data Cell
- Karlqvist gap, calculation of magnetic field in ferromagnetic layer
- Rotronics Wafadrive, 1984 endless tape drive
- ZX Microdrive, 1983 endless tape drive
References
- ↑ 1.0 1.1 Pär Rittsel (2002) (in sv), Valsen inledde skivans historia, International Data Group (published 2010-09-11), http://www.idg.se/2.10186/1.217236/valsen-inledde-skivans-historia, retrieved 2016-03-22
- ↑ (in sv) Magnetband till karusellminne, Föremål, Kringla, Riksantikvarieämbetet, http://www.kringla.nu/kringla/objekt;jsessionid=9DD1B26C1E65FD73160B49DF921B73D5?referens=tekm/object/TM38278, retrieved 2016-03-22
- ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 FACIT electronics AB (1961) (in sv), TPU 610301 FACIT ECM 64 Karusellminne, Preliminär teknisk beskrivning, Swedish National Museum of Science and Technology (published 2012-06-15), p. 3, http://www.tekniskamuseet.se/download/18.4d755928124885167d48000388/1339755649132/TM39138Bil3_+FacitECM64_+karusellminne_+prelteknisk+beskrivning.pdf
- ↑ 4.0 4.1 FACIT electronics AB (1963) (in sv), Facit Electronic presenterar FACIT ECM 64 Magnetbandsminne av karuselltyp med direkt access, Swedish National Museum of Science and Technology (published 2012-06-15), http://www.tekniskamuseet.se/download/18.4d755928124885167d48000387/1339755649101/TM39138Bil1_FacitECM64_broschyr-+Magnetbandsminneavkaruselltypmeddirektaccess.pdf
- ↑ Arvidsson, Göran (2002) (in sv), FACIT i den tidiga dataåldern (published 2015-08-23), pp. 3, http://www.brukskultur.se/uploadedFiles/81_data.pdf
Further reading
- Karlqvist, Olle (March 1962), "Applications to the magnetic tape storage unit, facit ECM64 (the Carousel Memory)", BIT Numerical Mathematics 2 (1): 16–20, doi:10.1007/BF02024778
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