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Apple FileWare
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<h2 id="history">History</h2> <p>In 1978, Apple intended to develop its own FileWare drive mechanism for the new Apple III and <a href="/facts/Apple_Lisa/PJpJhNRK">Lisa</a> business computers being developed. They quickly ran into difficulties which precluded them from the Apple III, which continued to use the earlier Shugart design.<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a> Finally, FileWare drives were implemented in the Lisa, released on January 19, 1983. The original <a href="/facts/Macintosh_128K/oXlQGVpX">Macintosh</a> was originally intended to have a Shugart drive, then a FileWare drive, then eventually shipped with <a href="/facts/Sony/7x4tCtBd">Sony</a>'s 3.5" 400k diskette drive. 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.<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a> </p> <h2 id="drive">Drive</h2> <p>FileWare drive is 5¼-inch double-sided, but not compatible with industry-standard diskettes. In a single-sided floppy drive, the <a href="/facts/Disk_read-and-write_head/WdpxUpjK">disk head</a> is opposed by a <a href="/facts/Foam/kGrXWWcb">foam</a> pressure pad. In a normal double-sided floppy disk drive, the top and bottom heads are almost directly opposed. Apple was concerned about head wear, and instead designed the FileWare drive so the top and bottom heads are on opposite sides of the spindle, and each is opposed by a pressure pad. Because there is only one <a href="/facts/Linear_actuator/37YgKUP3">actuator</a> to move the heads, when one head is near the spindle, the other is near the outer rim of the disk.<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> </p><p>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 from that of standard drives, though conceptually similar to that of the Disk II. </p> <h2 id="diskette">Diskette</h2> <p>The FileWare diskette has the same overall jacket dimensions of a normal <a href="/facts/History_of_the_floppy_disk/wFvpehDV">5¼ inch diskette</a>, 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 has a corner cutout that keys the diskette to prevent insertion in an incorrect orientation, and a rectangular hole that the drive uses to latch the diskette in place, preventing removal until the software allows it. </p><p>FileWare drives use 62.5 <a href="/facts/Track_(disk_drive)/BBpuAxUK">tracks</a> per inch rather than the standard 48 or 96 TPI, and use high <a href="/facts/Flux/Aw3P5Bvb">flux density</a> (comparable to the later <a href="/facts/IBM/QszA7nwd">IBM</a> 1.2<a href="/facts/Megabyte/RBF4XpWb">MB</a> format introduced with the <a href="/facts/IBM_Personal_Computer/AT/YEVHpWKF">PC/AT</a>). This requires 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. </p> <h2 id="format">Format</h2> <p>The disk format uses <a href="/facts/Group_coded_recording/rz5tW8Jq">group coded recording</a> (GCR) in a manner very similar to that of the Disk II. The drive contains circuitry to allow software control over the motor speed, which is used to maintain near constant flux transition rate on all tracks, so that more data can be stored on the outer tracks. </p><p>Each physical <a href="/facts/Disk_sector/V1R9Ivul">sector</a> stores 512 data bytes and 12 tag bytes. Each side of the disk had 46 tracks, and the number of sectors per track varies from 15 to 22. This results in 851 sectors per side, or a total capacity of 871,424 bytes.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a> The <i>Lisa Hardware Manual</i> doesn't explicitly state the total number of sectors, but page 173 states that there are 4 tracks of 22 sectors, 7x21, 6x20, 6x19, 6x18, 6x17, 7x16, and 4x15. The <a href="/facts/Disk_controller/dfRSYlMq">controller</a> uses similar circuitry to the Disk II controller, but runs at twice the <a href="/facts/Clock_rate/w055Woaj">clock rate</a>. The controller uses a dedicated <a href="/facts/MOS_Technology/1eKsjBS1">MOS</a> <a href="/facts/MOS_Technology/1eKsjBS1">6504</a> <a href="/facts/Microprocessor/Fx9CaQht">microprocessor</a>; in the Lisa this is on the system <a href="/facts/I/O_card/QkWAPnxJ">I/O card</a>, and for the UniFile/DuoFile products, it is on an interface card that plugs into a peripheral expansion slot. The Lisa 2/10 and <a href="/facts/Macintosh_XL/ESnjvczq">Macintosh XL</a> I/O card use the <a href="/facts/Integrated_Woz_Machine/gb9R4nJq">IWM</a> controller chip to replace the <a href="/facts/Transistor-transistor_logic/z4bvHotl">TTL</a> chips of the earlier design. </p> <h2 id="reliability">Reliability</h2> <p>FileWare drives proved to be somewhat unreliable. In early 1984, Apple introduced the Lisa 2, which uses 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.<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a> </p> <h2 id="later-rarity">Later rarity</h2> <p>The nature of models with "Twiggy" floppy drives being prototypes typically meant they were therefore often destroyed around the time of original production. With the increased interest in old and rare Apple items, from the <a href="/facts/2010s/qUX1pjJD">2010s</a> onwards, non-destroyed original models found in collections have often gone-on to sell for relatively high prices at auction.<a class="footnote-ref" id="fnref:7" href="#fn:7"><sup>7</sup></a> </p> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>Apple Computer Inc.: Lisa schematics, 1981 <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>Apple and the Floppy Drive Archived May 6, 2007, at the Wayback Machine <a href="http://home.socal.rr.com/fuweb/floppysite/twiggy.html" target="_blank">http://home.socal.rr.com/fuweb/floppysite/twiggy.html</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>Lisa2 Archived 2011-07-20 at the Wayback Machine <a href="http://www.apple2world.jp/apple2/COL/MapItems/lisa2/lisa2.html" target="_blank">http://www.apple2world.jp/apple2/COL/MapItems/lisa2/lisa2.html</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Apple Computer Inc.: Lisa Hardware Reference Manual, 1983 <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>Berry, D. "LISA Hardware Manual - Final Draft September 7th 1982" (PDF). Bitsavers.org. Apple?. Retrieved 28 February 2022. <a href="http://www.bitsavers.org/pdf/apple/lisa/hardware/Lisa_Hardware_Manual_Sep82.pdf" target="_blank">http://www.bitsavers.org/pdf/apple/lisa/hardware/Lisa_Hardware_Manual_Sep82.pdf</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>Apple's Twiggy Disks <a href="http://www.brouhaha.com/~eric/retrocomputing/lisa/twiggy.html" target="_blank">http://www.brouhaha.com/~eric/retrocomputing/lisa/twiggy.html</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> <li id="fn:7"><p>"Rare Apple Macintosh Prototype From 1983 Could Break Auction Records". MacRumors. October 3, 2024. Retrieved 2024-03-03. <a href="https://www.macrumors.com/2024/10/03/rare-apple-macintosh-prototype-from-1983" target="_blank">https://www.macrumors.com/2024/10/03/rare-apple-macintosh-prototype-from-1983</a> <a href="#fnref:7" class="footnote-back-ref">↩</a></p></li> </ol>