Definition of "microdrive"

One-inch disks typically held about 8 to 10 GB and microdrives were either 2 or 4 GB.

2011, Geoff Varrall, Making Telecoms Work

There are lots of things that will benefit from being on a microdrive cartridge but if you release something on microdrive you're only going to sell it to people with microdrive.

1984, Alison Maguire, interviewed in SINCLAIR talks... (in Crash magazine, issue 3, April 1984)

The Spectrum has its own inexpensive mass storage unit - the microdrive which starts at about £150 for 100k of storage, but this may not be suitable in all cases, since the storage unit may be damaged if turned on with the disc in position.

1986, African Energy Programme (Commonwealth Science Council), Renewable energy development in Africa (volume 2, page 161)

Disk interfaces have been around since the year dot, as people soon realised that the microdrive was unreliable, unstable and generally rubbish for the storage of anything, useless except as a rather small beermat.

1989 June, Phil South, “Rage Hard”, in Your Sinclair‎, archived from the original on 10 March 2012

The microdrive was invented so that electrodes could be lowered into the brain in order to isolate new neurons.

2014, Masami Tatsuno, Analysis and Modeling of Coordinated Multi-neuronal Activity, page 23