CF-2 Compact Floppy Disk

Revision as of 04:31, 20 December 2020

The CF-2 Compact Floppy Disk (and its double-density variant CF2DD aka CF2-D), also known as three-inch discs, were one of several odd-sized floppy formats that never caught on. It was 3 inches in width, and larger in height (of the casing unit the users saw; the actual disk inside is round as usual). It was released around the same time as the 3½" disk, attempting a "VHS vs. Betamax" or "BluRay Disc vs. HD-DVD" style format war.

3" discs were mainly used in the 1980s and early 1990s. Machines which used them included:

• Various 8-bit machines by the company Amstrad (sold by Schneider in some markets):
  • Amstrad CPC
  • Amstrad PCW (aka "Joyce")
  • Spectrum +3
• Tatung Einstein

The discs could physically be inserted in a drive either way up, and single-density and double-density discs were mechanically identical. In a single-sided drive, the drive would only read/write one side of the medium; to access the other, you'd insert the disc the other way round. In a double-sided drive, you had to remember to only ever put the disc in one way up, and the drive would access both sides of the medium.

Many (most?) 3" discs will contain a CP/M file system.

Recovering data from 3" discs

Because this format was short-lived, getting data from a 3" drive to a modern computer can be hard. Options include:

Probably the most difficult problem with converting LocoScript documents into more readable formats is not the conversion process itself, but the fact that the majority of LocoScript files were stored on 3-inch floppy disks, which are now difficult to access. However, there are methods of transferring data if a working PCW is available.

• If you have a working machine with a 3" drive, you can use it to read the data and transfer it via some other interface the machine has. For instance, if your machine runs CP/M and has a serial (RS232) interface, you can run AUXD on the source machine and the LibDsk tools on the destination machine to transfer a disc image.
  • Unfortunately, some models of the Amstrad PCW in particular didn't come with any standard interfaces. There were add-ons such as the CPS8256 to give serial and parallel interfaces, or the LocoLink cable to connect to a PC's parallel port (which came with software to convert LocoScript files).
• An alternative is to connect a more common drive, such as a 3.5" drive, to your working 3" machine. Frank van Empel has a guide for the Amstrad PCW. (another guide)
• If you have only a 3" drive, it's usually possible to interface it to a PC (if the PC is old enough to have a floppy controller). Frank Van Empel has some details for Amstrad drives. Then you can use disc imaging software on the PC to recover the data (the PC's operating system is unlikely to understand the data structure natively).

The 3" drive might require maintenance first -- a common problem is that the drive belt tends to stretch. Here is a guide to renovating a drive (aimed at the Amstrad drives).

Links

• A Look at the Short-Lived 3-Inch Compact Floppy Disk
• A guide to 3" media
• Wikipedia:Floppy disk variants
• The Winning Move: Hitachi's 3 Inch Floppy (ad in Byte)