The ZX Microdrive was a magnetic tape data storage format introduced in 1983 by Sinclair Research for use with its ZX Spectrum home computer, and later used on the Sinclair QL and ICL One Per Desk computers as a cheaper alternative to floppy disk drives.
It used a cartridge with an endless loop of very narrow (1.9mm wide) tape with a maximum capacity of 85 KB (when formatted for use in a QL, this was increased to 100 KB). The loop was 5 metres in length, and a complete circuit took 8 seconds.
Blank and pre-recorded cartridges were available.
The Wafadrive was a similar format also marketed to ZX Spectrum owners.
The ZX Microdrive system gained a reputation for unreliability, one of the reasons being tape stretch which meant the cartridges had a short lifespan. When used with the QL and ICL One Per Desk, the system was modified to reduce tape stretch.
The Sinclair QL was discontinued in 1986, and by 1987, the ZX Spectrum +3 was introduced that had a built-in 3-inch floppy disk drive.
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