In my experience - Sinclair/ZX Microdrives (Score: 1) by fatphil@pipedot.org on 2014-05-19 21:01 (#1RM) One single continuous piece of tape, no spool, all zig-zaggy inside the case, that was quite literally shoved back into the cartridge as fast as it was being tugged out. 85KB capacity, IIRC. Innards of the drives visible here: http://www.binarydinosaurs.co.uk/scripts/picshow.php?image=qlmicrodrives.jpg&folder=/Museum/Sinclair/ql&back=/Museum/Sinclair/ql/index.php . Although initially developed for the BT Merlin and the Sinclail QL, I had one on my ZX Spectrum as I splashed out on Interface 1.Dire is the only word for them.However, the drives were significantly lighter than the 40kg unit which I used to read these: http://fatphil.org/images/im_floppier.jpg