User:Ferrofield/Carousel memory



Erik Stemme and Gunnar Stenudds created the carousel memory. It was shown for the first time at a exhibition in Paris in 1958.

Facit ECM 64
The FACIT ECM 64 used another technique than a long tape. Instead 64 small rolls with 9 meters, 1.6 cm wide tape on each roll, divided into 8 channels. The tape speed is 5 m/s. To read a specific roll the carousel were rotated such that the 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 fast re-winded back. The average seek time was 2 seconds and the storage space was 2560 kByte. The control system were completely transistorized. Both the carousel and individual spools could be replaced.

The magnetic tape used 5/8 inch (1.6 cm) wide, 0.05 mm thick Mylar 3M Co type 188. The storage density is specified to 8 bits/mm and the access head had the capability for simultaneous read- and write operation. 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.

Peak transfer speed was 182 044 bits/s using 8-parallell lines 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.