Carousel memory
A Swedish carousel of 64 small magnetic tape rolls.
Carousel memory is a type of secondary storage for computers, created by Swedish computer engineers and Gunnar Stenudd. It was first shown at an exhibition in Paris in 1958. The design avoids a single long magnetic tape by using multiple small tape rolls arranged in a carousel.
- Created by
- Swedish computer engineers and Gunnar Stenudd
- First shown
- 1958, Paris
- Manufacturer
- Facit AB
- Model
- FACIT ECM 64
- Number of tape rolls
- 64
- Tape width
- 5/8 inch (1.6 cm)
- Tape thickness
- 0.05 mm
- Tape material
- Mylar 3M Co type 188
- Average seek time
- specified
- Storage space
- specified
Lore & Background
The carousel memory was developed by Swedish engineers, including Gunnar Stenudd, and first exhibited in Paris in 1958. The Facit ECM 64, a prototype manufactured by Facit AB, uses 64 small rolls of magnetic tape, each with wide tape divided per roll. To access a specific roll, the carousel rotates until the desired roll is at the bottom. A counterweight at the free end of the tape helps the roll move down into a mechanism with a read-and-write head, after which the tape is rewound. The control system uses transistors, and both the carousel and individual spools are replaceable. The magnetic tape is 5/8-inch (1.6 cm) wide and 0.05 mm thick Mylar 3M Co type 188. The access head can perform simultaneous read and write operations. The first delivery of the Facit EDB 3 computer, in 1958 to ASEA in Västerås, used the carousel memory Facit ECM 64.
Reader's Guide
Carousel memory represents an early approach to secondary storage that sought to balance capacity and access speed by distributing data across multiple small tape rolls rather than a single long reel. Its use of a rotating carousel to select a roll, combined with a read/write head mechanism, provided a seek time and storage space that were specified for the era. The system's reliance on transistors for control and its ability to perform simultaneous read/write operations were notable for the late 1950s. The first deployment in the Facit EDB 3 computer at ASEA in Västerås in 1958 demonstrates its practical application in early Swedish computing. While later technologies such as the Exatron Stringy Floppy, Rotronics Wafadrive, and ZX Microdrive also used endless tape drives, carousel memory's multi-roll design was distinct. The IBM 2321 Data Cell is a related concept in storage architecture.
Did You Know?
- The Facit ECM 64 uses 64 small rolls of magnetic tape.
- The first delivery of the Facit EDB 3 computer, using carousel memory, was to ASEA in Västerås in 1958.
Frequently Asked Questions
What is Carousel memory?
Carousel memory is a secondary storage format for computers that replaces a single long magnetic tape with a ring of smaller, individual tape rolls. It was designed by Swedish computer engineers working alongside Gunnar Stenudd.
Who made the Carousel memory device?
The hardware was manufactured by Facit AB under the model designation FACIT ECM 64. The underlying design is credited to Swedish computer engineers and Gunnar Stenudd.
When and where was Carousel memory first shown to the public?
The device made its public debut at an exhibition in Paris in 1958.
How does Carousel memory differ from a standard single-tape drive?
Instead of spooling one continuous strip of tape, the drive indexes across 64 separate small rolls arranged in a circular carousel. This layout lets the mechanism hop to the needed roll rather than winding through an entire long tape.
What are the key physical specifications of the FACIT ECM 64?
The unit holds 64 individual tape rolls, each carrying 5/8-inch (1.6 cm) wide magnetic tape. It was built by Facit AB as a Swedish-made secondary storage solution.
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