Apple FileWare
Encyclopedia
FileWare floppy disk drives
and diskettes were designed by Apple Computer
as a higher-performance alternative to the Disk II
and Disk III floppy systems used on the Apple II
and Apple /// personal computers. The drives were also referred to as Apple 871 drives in service documentation, based on their approximate formatted storage capacity in kilobyte
s, but were most commonly known by their code name, Twiggy, after a 1960s fashion model (Twiggy
) who was famously thin.
business computers being developed. They quickly ran into difficulties which precluded them from being incorporated in the Apple ///, which continued to use the earlier Shugart design. FileWare drives were finally introduced with the Apple Lisa
computer in 1983, and were used in prototypes of the Apple Macintosh. Although Apple planned to make FileWare drives available for the Apple II and Apple III, and announced them under the names UniFile and DuoFile (for single and dual drives, respectively), these products were never shipped.
is opposed by a foam
pressure pad. In a normal double-sided floppy disk drive, the top and bottom heads are almost directly opposed to each other. Apple was concerned about head wear, and instead designed the FileWare drive such that the top and bottom heads are on opposite sides of the spindle, and each is opposed by a pressure pad. Since there is only one actuator
to move the heads, when one head is near the spindle, the other is near the outer rim of the disk.
The drive is approximately the same size as a standard full-height 5¼ inch floppy drive, but does not use the standard mounting hole locations. The electrical interface is completely different than that of standard drives, though conceptually similar to that of the Disk II.
FileWare drives used 62.5 tracks
per inch rather than the standard 48 or 96 TPI, and used high flux density
(comparable to the later IBM
1.2MB format introduced with the PC/AT). This required custom high-density media. The coercivity required is similar to that of the 1.2MB format, so it is possible to modify the jacket of 1.2MB diskettes for use in a FileWare drive.
in a manner very similar to that of the Disk II. The drive contained circuitry to allow software control over the motor speed, which was used to maintain near constant flux transition rate on all tracks, so that more data could be stored on the outer tracks.
Each physical sector stored 512 data bytes and 20 tag bytes. The controller used similar circuitry to the Disk II controller, but ran at twice the clock rate. The controller used a dedicated MOS
6504 microprocessor; in the Lisa this was on the system I/O card, and for the UniFile/DuoFile products, it was on an interface card that plugged into a peripheral expansion slot. The Lisa 2/10 and Macintosh XL
I/O card used the IWM controller chip to replace the TTL
chips of the earlier design.
floppy drive.
Floppy disk
A floppy disk is a disk storage medium composed of a disk of thin and flexible magnetic storage medium, sealed in a rectangular plastic carrier lined with fabric that removes dust particles...
and diskettes were designed by Apple Computer
Apple Computer
Apple Inc. is an American multinational corporation that designs and markets consumer electronics, computer software, and personal computers. The company's best-known hardware products include the Macintosh line of computers, the iPod, the iPhone and the iPad...
as a higher-performance alternative to the Disk II
Disk II
The Disk II Floppy Disk Subsystem was a 5¼-inch floppy disk drive designed by Steve Wozniak and manufactured by Apple Computer. It was first introduced in 1978 at a retail price of US$495 for pre-order; it was later sold for $595 including the controller card and cable...
and Disk III floppy systems used on the Apple II
Apple II
The Apple II is an 8-bit home computer, one of the first highly successful mass-produced microcomputer products, designed primarily by Steve Wozniak, manufactured by Apple Computer and introduced in 1977...
and Apple /// personal computers. The drives were also referred to as Apple 871 drives in service documentation, based on their approximate formatted storage capacity in kilobyte
Kilobyte
The kilobyte is a multiple of the unit byte for digital information. Although the prefix kilo- means 1000, the term kilobyte and symbol KB have historically been used to refer to either 1024 bytes or 1000 bytes, dependent upon context, in the fields of computer science and information...
s, but were most commonly known by their code name, Twiggy, after a 1960s fashion model (Twiggy
Twiggy
Lesley Lawson née Hornby known as Twiggy is an English model, actress, and singer. In the early-1960s she became a prominent British teenage model of swinging sixties London with others such as Penelope Tree....
) who was famously thin.
History
In 1978, Apple intended to develop its own FileWare drive mechanism for use in the new Apple /// and LisaApple Lisa
The Apple Lisa—also known as the Lisa—is a :personal computer designed by Apple Computer, Inc. during the early 1980s....
business computers being developed. They quickly ran into difficulties which precluded them from being incorporated in the Apple ///, which continued to use the earlier Shugart design. FileWare drives were finally introduced with the Apple Lisa
Apple Lisa
The Apple Lisa—also known as the Lisa—is a :personal computer designed by Apple Computer, Inc. during the early 1980s....
computer in 1983, and were used in prototypes of the Apple Macintosh. Although Apple planned to make FileWare drives available for the Apple II and Apple III, and announced them under the names UniFile and DuoFile (for single and dual drives, respectively), these products were never shipped.
Drive
FileWare drives are 5¼-inch double-sided, but are not mechanically compatible with industry-standard diskettes. In a single-sided floppy disk drive, the disk headDisk read-and-write head
Disk read/write heads are the small parts of a disk drive, that move above the disk platter and transform platter's magnetic field into electrical current or vice versa – transform electrical current into magnetic field...
is opposed by a foam
Foam
-Definition:A foam is a substance that is formed by trapping gas in a liquid or solid in a divided form, i.e. by forming gas regions inside liquid regions, leading to different kinds of dispersed media...
pressure pad. In a normal double-sided floppy disk drive, the top and bottom heads are almost directly opposed to each other. Apple was concerned about head wear, and instead designed the FileWare drive such that the top and bottom heads are on opposite sides of the spindle, and each is opposed by a pressure pad. Since there is only one actuator
Linear actuator
A linear actuator is an actuator that creates linear motion .Mechanical and hydraulic actuation are the most common methods of achieving the linear motion...
to move the heads, when one head is near the spindle, the other is near the outer rim of the disk.
The drive is approximately the same size as a standard full-height 5¼ inch floppy drive, but does not use the standard mounting hole locations. The electrical interface is completely different than that of standard drives, though conceptually similar to that of the Disk II.
Diskette
The FileWare diskette has the same overall jacket dimensions of a normal 5¼ inch diskette, but because of the head arrangement, the jacket has non-standard cutouts for the heads, with two sets of cutouts on opposite sides of the spindle hole. The write enable sensor is also in a non-standard location, though most FileWare diskettes were produced without a write protect slot. The jacket had a corner cutout that keyed the diskette to prevent insertion in an incorrect orientation, and a rectangular hole that the drive could use to latch the diskette in place, preventing removal until the software allowed it.FileWare drives used 62.5 tracks
Track (disk drive)
A disk drive track is a circular path on the surface of a disk or diskette on which information is magnetically recorded and from which recorded information is read....
per inch rather than the standard 48 or 96 TPI, and used high flux density
Flux density
-Formal Statement:The flux density is simply defined as the amount of flux passing through a unit-area. -Mathematical Statement:The flux density would essentially be the number of field lines passing through a defined unit-area...
(comparable to the later IBM
IBM
International Business Machines Corporation or IBM is an American multinational technology and consulting corporation headquartered in Armonk, New York, United States. IBM manufactures and sells computer hardware and software, and it offers infrastructure, hosting and consulting services in areas...
1.2MB format introduced with the PC/AT). This required custom high-density media. The coercivity required is similar to that of the 1.2MB format, so it is possible to modify the jacket of 1.2MB diskettes for use in a FileWare drive.
Format
The disk format used GCRGroup Code Recording
In computer science, group code recording refers to several distinct but related encoding methods for magnetic media. The first, used in 6250 cpi magnetic tape, is an error-correcting code combined with a run length limited encoding scheme...
in a manner very similar to that of the Disk II. The drive contained circuitry to allow software control over the motor speed, which was used to maintain near constant flux transition rate on all tracks, so that more data could be stored on the outer tracks.
Each physical sector stored 512 data bytes and 20 tag bytes. The controller used similar circuitry to the Disk II controller, but ran at twice the clock rate. The controller used a dedicated MOS
MOS Technology
MOS Technology, Inc., also known as CSG , was a semiconductor design and fabrication company based in Norristown, Pennsylvania, in the United States. It is most famous for its 6502 microprocessor, and various designs for Commodore International's range of home computers.-History:MOS Technology, Inc...
6504 microprocessor; in the Lisa this was on the system I/O card, and for the UniFile/DuoFile products, it was on an interface card that plugged into a peripheral expansion slot. The Lisa 2/10 and Macintosh XL
Macintosh XL
Macintosh XL was a modified version of the Apple Lisa personal computer made by Apple Computer, Inc. In the Macintosh XL configuration, the computer shipped with MacWorks XL, a Lisa program that allowed 64 K Macintosh ROM emulation...
I/O card used the IWM controller chip to replace the TTL
Transistor-transistor logic
Transistor–transistor logic is a class of digital circuits built from bipolar junction transistors and resistors. It is called transistor–transistor logic because both the logic gating function and the amplifying function are performed by transistors .TTL is notable for being a widespread...
chips of the earlier design.
Reliability
In the field, the FileWare drives proved to be somewhat unreliable. In early 1984, Apple introduced the Lisa 2, which used a single 3½ inch Sony floppy drive in place of the two FileWare drives of the original Lisa. A free upgrade was offered to Lisa 1 owners. The Macintosh was also introduced using the SonySony
, commonly referred to as Sony, is a Japanese multinational conglomerate corporation headquartered in Minato, Tokyo, Japan and the world's fifth largest media conglomerate measured by revenues....
floppy drive.