FileWare disks (commonly known as Twiggy disks after the very thin 1960s fashion model) were a type of floppy disk for data storage, and were introduced by Apple in 1983 for use in the Apple Lisa computer. They were initially intended for use in the Apple III, Lisa and Macintosh computers, but the Apple III was launched in 1981 with a standard 5.25-inch floppy disk drive, offering 140 KB, and the Macintosh was launched in 1984 with a single-sided 3.5-inch microfloppy disk offering 400 KB. A prototype Macintosh was produced with a FileWare drive, but this was dropped before launch. In the end, the only computer to use the FileWare drive was the Apple Lisa I, launched in 1983 and aimed at the business market. Despite being far ahead of its time in number of respects, not least for being the first widely available computer with a graphical user interface, the Apple Lisa was commercially unsuccessful.
Apple had already built its own drive controller for the Apple II, designed by Steve Wozniak, and the logical next step seemed to be to design its own drive so it could continue the boast that anything ‘Not Invented Here’ was not worth using.
The disks are very similar (but incompatible with) the Shugart designed 5.25-inch floppy disk and share the same dimensions. FileWare drives use two heads on either side of the spindle, and these are opposed by foam pressure pads, in an attempt to reduce wear. The outer jacket has different cut-outs to a standard 5.25- inch floppy disk, with two read slots. The write protect cutout is also in a different location, and there was a corner cutout to enable the drive to lock the disk in place since like Macintosh drives, the software ejects the disk only when it is ready to do so.
By using double-sided media, a higher track pitch, variable motor speed, and GCR recording, Apple achieved a formatted storage capacity of 871 KB per disk, compared to the 140 KB of the Disk II and 360 KB on the IBM PC. By the following year however, the IBM PC AT had a 5.25-inch disk drive offering 1.2 MB. It has been reported that modifying the outer jacket of a 1.2 MB disk will enable it to be read by a FileWare drive, but it does not increase the capacity.
FileWare drives proved to be somewhat unreliable in use and in early 1984 Apple introduced the Lisa 2, which used a single 400 KB 3.5-inch microfloppy disk drive in place of the two FileWare drives of the original Lisa. A free upgrade was offered to Lisa 1 owners, requiring owners to send back their FileWare drives and the Lisa faceplate to get the replacement drive, so Lisa I models are fairly rare, as are the disks. Only 1,000 Lisa 1 models we sold (due in part to the $10,000 price tag), and many of these were upgraded to Lisa 2.
In 1984, Apple shareholders brought a lawsuit against the company alleging that they knew about the unreliability of the drives in 1982 but continued to launch them in the Lisa despite internal memos warning of the high failure rate. The judgement went against two Apple executives in 1991, but was subsequently overturned.