FDHD refers to a floppy drive high density mechanism (also marketed as a "SuperDrive"), introduced by Apple Computer in the Macintosh IIx in 1988, and last used in the "beige" Power Macintosh G3 all-in-one in 1998.
Description
The controller for FDHD mechanisms is called the SWIM chip (an abbreviation of Super Wozniak Integrated Machine or Sander-Wozniak Integrated Machine, according to different accounts. The SWIM chip replaced the Integrated Woz Machine (IWM) for older 800 KB floppy mechanisms.[1] It was available as part of an Apple FDHD Macintosh II Upgrade Kit (part number M0244).[2]
The newer floppy drive mechanism could read 1.4 MB high-density floppy disks, as well as disks formatted for other operating systems. However, reading MS-DOS or ProDOS disks initially required the use of Apple File Exchange, until PC Exchange became available in 1992.[1][3]
An external Apple FDHD Drive (part number G7287) was also marketed, but if used with a Macintosh or Apple II series computer without a SWIM chip in the system or controller card, would only function as a 800 KB drive.[4]
Issues
Users found that high-density floppies that had previously been used in a 800 KB drive were unreliable when reformatted for high-density use. This was because the FDHD mechanism switched to a weaker magnetic field to write to smaller sectors, sometimes being unable to thoroughly erase data written with a stronger magnetic field from an 800 KB drive. A workaround was to use a powerful magnetic field from a bulk tape eraser to wipe such disks.[1]
References
- ↑ 1.0 1.1 1.2 SuperDrives Stumble, TidBITS no.2. 1990-04-23.
- ↑ Apple Macintosh II M0244 FDHD ROM/SWIM Upgrade Kit (M0244 part only) new sealed, WorthPoint. 2017-10-18.
- ↑ Round Up the Usual Suspects by Doug and Denise Green, InfoWorld Target Edition, p.S13. 1989-08-07.
- ↑ FDHD/SuperDrive Manual by Mac128, 68k Macintosh Liberation Army. 2012-01-23.
External links
- Apple Technical Procedures: Apple FDHD Drive (PDF) by Apple Computer (1989-10, mirrored)
- Today in Apple history: Macintosh SE gets supersized storage by Luke Dormehl at Cult of Mac (2020-08-01)
- SuperDrive: Floppy disk drive and Macintosh External Disk Drive: Apple FDHD Drive at Wikipedia
