Dimensions are 80x100x5mm. (more or less, depending the manufacturer)
(This article, [[:File:Amstrad Computer User8504 072.jpg]], also mentions something called Hitachi HFD-2 discs.)
In 1982 to 1983, there were some "microfloppy" formats competing to replace the 5¼″ floppy. However, in 1984 Apple choose the Sony 3½″ drives for their Macintosh computer. The Sony format became the de facto microfloppy standard but other formats, including the Hitachi 3″ and the 5¼″ still had plenty of life left in it. In 1987 IBM choose 3½″ in PS/2 PC architecture.
Alan Sugar, sign a deal with the manufacturers of three-inch disk drives to sell him units at a fixed percentage beneath the lowest-priced 3.5-inch drive, he got the cheapest option going for generations of computers. In 1985 a CPC computer appeared with 3" floppy. Towards the end, it was rumoured, Hitachi had to keep a factory going just for Amstrad — it lost money on each drive, but not as much as if it had broken the contract. 3" format saw its finest hour in the PCW range of CP/M word processors which sold by the million: its passing leaves the world with a legacy of documents.
* CF2 Drive hardware makers:
* Computers and Media Drives that use 3" CF2 standard:
- AMDECK (AMDISK) [1982] : external drive for TRS-80 , IBM PC , Atari 400/800 , Apple II
- YAMAHA MDR-1 [1983] : squencer sequencer for professional organs. Pre-MIDI
- National MyBrain 3000 [1983] : computer
- Gavilan Laptop [1983]
- Timex FDD / FDD-3000 drive ( for ZX Spectrum and Timex ) [1985]
- Amstrad / Schneider CPC [1985]
- Amstrad / Schneider PCW (8000 series) [1985]
- Sinclair Spectrum +3 [1987]
- Amstrad PCW 9000 series [1987]
- Amstrad CPC+ [1990]
PCW 8000 drive B or 9000 series drive A can handle the DD format (720k). Spectrum +3 bios can handle too if you add one of those PCW units (or 3,5" drive). Some CPC utils and ROMS would use PCW format (Knife) or PC DOS 720k format (BonnyDOS)
== 3 Inch Discs Comments from John King ==