illustration.xml

<section xmlns="http://docbook.org/ns/docbook"
         xml:id="VDG-Appendix-Disk-Drive-Components"
         xmlns:xl="http://www.w3.org/1999/xlink"
         version="5.1">

  <title>Disk Drive Components</title>

  <para>
    In the early days of computing, direct access storage devices
    (i.e., <quote>hard disk drives</quote>) were much simpler. A
    simple device meant a less complex method for interaction was
    necessary. Two standards define how communication with disk drives
    may happen: The IDE/ATA standard for communicating with disk
    drives, and the BIOS Int 13h standard (<quote>disk
    services</quote>) for how operating systems can interact with disk
    drives via software interrupts

    <footnote>
      <para>
	BIOS Enhanced Disk Drive Specification v3: <link
	xl:href="http://www.t13.org/documents/UploadedDocuments/technical/d98120r0.pdf"
	/>
      </para>
    </footnote>

    <footnote>
      <para>
	PC Guide - Int 13h: <link
	xl:href="http://www.pcguide.com/ref/hdd/bios/bios_Int13h.htm"/>
      </para>
    </footnote>

    .
  </para>

  <para>
    A disk drive was originally composed of a few simple components:
  </para>

  <itemizedlist>
    <listitem>
      <para>
        One called a <firstterm>head</firstterm> which is mounted on a
        swinging arm. The arm swings across a disk platter to move the
        head to the sector requested for a read or write
        operation. More platters in a disk drive mean more heads and
        arms.
      </para>
    </listitem>
    <listitem>
      <para>
        An array of magnetized spinning disks called
        <firstterm>platters</firstterm>. Because each side of a platter
        is used to store data there must be two heads for each
        platter.
      </para>
    </listitem>
    <listitem>
      <para>
        For the purpose of addressing a specific location on a platter
        each platter is further broken down into
        <firstterm>cylinders</firstterm> (or
        <firstterm>tracks</firstterm>), and
        <firstterm>sectors</firstterm>.
      </para>
    </listitem>
  </itemizedlist>

  <figure xml:id="VDG-Appendix-Disk-Drive-History-Illustration-Figure">
    <title>Disk Drive Components</title>
    <mediaobject>
      <imageobject audience="html">
        <imagedata fileref="./images/disk-structure.png"/>
      </imageobject>
      <imageobject audience="pdf">
        <imagedata fileref="../../../images/disk-structure.png"/>
      </imageobject>
      <textobject><phrase>Disk Drive Components</phrase></textobject>
    </mediaobject>
  </figure>
</section>