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<P class=MsoNormal 
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align=left><FONT size=2></FONT>&nbsp;</P>
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<TABLE cellSpacing=0 cellPadding=0 width="100%" border=1>
  <TBODY>
  <TR>
    <TD><STRONG><FONT face="Times New Roman TUR">驱动器及软盘类型</FONT></STRONG></TD>
    <TD><STRONG><FONT face="Times New Roman TUR">每面磁道数</FONT></STRONG></TD>
    <TD><STRONG><FONT face="Times New Roman TUR">每磁道扇区数</FONT></STRONG></TD>
    <TD><STRONG><FONT face="Times New Roman TUR">RPM</FONT></STRONG></TD>
    <TD><STRONG><FONT face="Times New Roman TUR">传输速率</FONT></STRONG></TD></TR>
  <TR>
    <TD><FONT face="Times New Roman TUR">360K,5.25英寸</FONT></TD>
    <TD><FONT face="Times New Roman TUR">40</FONT></TD>
    <TD><FONT face="Times New Roman TUR">9</FONT></TD>
    <TD><FONT face="Times New Roman TUR">300</FONT></TD>
    <TD><FONT face="Times New Roman TUR">250Kbps</FONT></TD></TR>
  <TR>
    <TD><FONT face="Times New Roman TUR">1.2M,5.25英寸</FONT></TD>
    <TD><FONT face="Times New Roman TUR">40</FONT></TD>
    <TD><FONT face="Times New Roman TUR">9</FONT></TD>
    <TD><FONT face="Times New Roman TUR">360</FONT></TD>
    <TD><FONT face="Times New Roman TUR">300Kbps</FONT></TD></TR>
  <TR>
    <TD><FONT face="Times New Roman TUR">1.2M,5.25英寸</FONT></TD>
    <TD><FONT face="Times New Roman TUR">80</FONT></TD>
    <TD><FONT face="Times New Roman TUR">15</FONT></TD>
    <TD><FONT face="Times New Roman TUR">360</FONT></TD>
    <TD><FONT face="Times New Roman TUR">500Kbps</FONT></TD></TR>
  <TR>
    <TD><FONT face="Times New Roman TUR">720K,3.5英寸</FONT></TD>
    <TD><FONT face="Times New Roman TUR">80</FONT></TD>
    <TD><FONT face="Times New Roman TUR">9</FONT></TD>
    <TD><FONT face="Times New Roman TUR">360</FONT></TD>
    <TD><FONT face="Times New Roman TUR">250Kbps</FONT></TD></TR>
  <TR>
    <TD><FONT face="Times New Roman TUR">1.44M,3.5英寸</FONT></TD>
    <TD><FONT face="Times New Roman TUR">80</FONT></TD>
    <TD><FONT face="Times New Roman TUR">9</FONT></TD>
    <TD><FONT face="Times New Roman TUR">360</FONT></TD>
    <TD><FONT face="Times New Roman TUR">250Kbps</FONT></TD></TR>
  <TR>
    <TD><FONT face="Times New Roman TUR">1.44M,3.5英寸</FONT></TD>
    <TD><FONT face="Times New Roman TUR">80</FONT></TD>
    <TD><FONT face="Times New Roman TUR">18</FONT></TD>
    <TD><FONT face="Times New Roman TUR">360</FONT></TD>
    <TD><FONT face="Times New Roman TUR">500Kbps</FONT></TD></TR>
  <TR>
    <TD><FONT face="Times New Roman TUR">2.88M,3.5英寸</FONT></TD>
    <TD><FONT face="Times New Roman TUR">80</FONT></TD>
    <TD><FONT face="Times New Roman TUR">9</FONT></TD>
    <TD><FONT face="Times New Roman TUR">360</FONT></TD>
    <TD><FONT face="Times New Roman TUR">250Kbps</FONT></TD></TR>
  <TR>
    <TD><FONT face="Times New Roman TUR">2.88M,3.5英寸</FONT></TD>
    <TD><FONT face="Times New Roman TUR">80</FONT></TD>
    <TD><FONT face="Times New Roman TUR">18</FONT></TD>
    <TD><FONT face="Times New Roman TUR">360</FONT></TD>
    <TD><FONT face="Times New Roman TUR">500Kbps</FONT></TD></TR>
  <TR>
    <TD><FONT face="Times New Roman TUR">2.88M,3.5英寸</FONT></TD>
    <TD><FONT face="Times New Roman TUR">80</FONT></TD>
    <TD><FONT face="Times New Roman TUR">36</FONT></TD>
    <TD><FONT face="Times New Roman TUR">360</FONT></TD>
    <TD><FONT face="Times New Roman TUR">1Mbps</FONT></TD></TR></TBODY></TABLE></P>
<P class=MsoNormal 
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align=center><FONT face="Times New Roman TUR" size=3>表1-5-1 
软盘种类表</FONT></P><STRONG>
<HR width="100%" SIZE=1>

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<P class=MsoNormal 
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align=left><STRONG>软盘参数表</STRONG></P>
<P class=MsoNormal 
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<P class=MsoNormal 
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align=left><FONT face="Times New Roman TUR" 
size=3>在BIOS的中断向量表中断1Eh的地址0:78h处(参见</FONT><A 
href="javascript:if(confirm('http://pagoda-ooos.51.net/os_book/appendix-bios-interrupt-overview_a_1.htm%20%20\n\nThis%20file%20was%20not%20retrieved%20by%20Teleport%20Pro,%20because%20the%20server%20reports%20that%20this%20file%20cannot%20be%20found.%20%20\n\nDo%20you%20want%20to%20open%20it%20from%20the%20server?'))window.location='http://pagoda-ooos.51.net/os_book/appendix-bios-interrupt-overview_a_1.htm'" 
tppabs="http://pagoda-ooos.51.net/os_book/appendix-bios-interrupt-overview_a_1.htm"><FONT 
face="Times New Roman TUR" color=#000000 size=3>A.1 BIOS Interrupt 
Overview</FONT></A><FONT face="Times New Roman TUR" size=3>),保存着指向存放于系统BIOS 
ROM中的软盘参数表的远指针(远指针指需要通过segment:offset的方式来制定的指针,它所指向的地址可以跨越不同的64K段;而近指针则只需要通过offset来制定同一段内的另外一个地址)。里面包含了有关驱动器(Driver)的信息。BIOS使用这个表来为软盘控制器编程和指定软驱的控制定时——当某个程序调用13h中断来使用软盘服务时,BIOS将会使用软盘参数表中提供的数据来对软盘控制器进行编程。</FONT></P>
<P class=MsoNormal 
style="MARGIN: 0cm 0cm 0pt 21pt; TEXT-INDENT: -21pt; tab-stops: list 21.0pt; mso-list: l5 level1 lfo3" 
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<P class=MsoNormal 
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align=left><FONT face="Times New Roman TUR"><FONT 
size=3>软盘参数表是一个重要的概念——如果系统上只有一个驱动器类型,正像早期的PC和XT系统一样。参数表在早期的PS/2上工作得也很好,在这里要从两种类型的驱动器中选择一个,比如3.5英寸,1.44M。<STRONG>软盘参数表用于完整的定义驱动器参数。</STRONG></FONT></FONT></P>
<P class=MsoNormal 
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align=left><FONT face="Times New Roman TUR" size=3>下表为软盘参数表的概要内容:</FONT></P>
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<TABLE cellSpacing=0 cellPadding=0 width="100%" border=1>
  <TBODY>
  <TR>
    <TD><FONT face="Times New Roman TUR">偏移量</FONT></TD>
    <TD><FONT face="Times New Roman TUR">描述</FONT></TD></TR>
  <TR>
    <TD><FONT face="Times New Roman TUR">0</FONT></TD>
    <TD><FONT face="Times New Roman TUR">软盘控制器(端口3F5h)</FONT></TD></TR>
  <TR>
    <TD><FONT face="Times New Roman TUR">1</FONT></TD>
    <TD><FONT face="Times New Roman TUR">软盘控制器(端口3F5h)</FONT></TD></TR>
  <TR>
    <TD><FONT face="Times New Roman TUR">2</FONT></TD>
    <TD><FONT face="Times New Roman TUR">驱动器休眠马达关闭延时</FONT></TD></TR>
  <TR>
    <TD><FONT face="Times New Roman TUR">3</FONT></TD>
    <TD>
      <P><FONT face="Times New Roman TUR">每扇区字节数:</FONT></P>
      <P><FONT face="Times New Roman TUR">0=128 bytes;1=256 bytes;2=512 
      bytes;3=1024 bytes;</FONT></P>
      <P><FONT face="Times New Roman TUR">4=2048 bytes;5=4096 bytes;7=16384 
      bytes;8-FFh=Reserverd</FONT></P></TD></TR>
  <TR>
    <TD><FONT face="Times New Roman TUR">4</FONT></TD>
    <TD>
      <P><FONT face="Times New Roman TUR">每磁道的扇区数:</FONT></P>
      <P><FONT face="Times New Roman TUR">9=9 sectors;360K和720K</FONT></P>
      <P><FONT face="Times New Roman TUR">0Fh=15 sectors;1.2M</FONT></P>
      <P><FONT face="Times New Roman TUR">12h=18 sectors;1.44M</FONT></P>
      <P><FONT face="Times New Roman TUR">24h=36 sectors;2.88M</FONT></P></TD></TR>
  <TR>
    <TD><FONT face="Times New Roman TUR">5</FONT></TD>
    <TD>
      <P><FONT face="Times New Roman TUR">扇区之间的间隙长度:</FONT></P>
      <P><FONT face="Times New Roman TUR">1Bh for 1.2M,1.44M and 2.88M 
      floppy</FONT></P>
      <P><FONT face="Times New Roman TUR">2Ah for 360K and 720K 
    floppy</FONT></P></TD></TR>
  <TR>
    <TD><FONT face="Times New Roman TUR">6</FONT></TD>
    <TD><FONT face="Times New Roman TUR">数据长度</FONT></TD></TR>
  <TR>
    <TD><FONT face="Times New Roman TUR">7</FONT></TD>
    <TD><FONT face="Times New Roman TUR">格式化间隙长度</FONT></TD></TR>
  <TR>
    <TD><FONT face="Times New Roman TUR">8</FONT></TD>
    <TD><FONT face="Times New Roman TUR">格式化填充字节</FONT></TD></TR>
  <TR>
    <TD><FONT face="Times New Roman TUR">9</FONT></TD>
    <TD><FONT face="Times New Roman TUR">磁头定位时间</FONT></TD></TR>
  <TR>
    <TD><FONT face="Times New Roman TUR">A</FONT></TD>
    <TD><FONT 
face="Times New Roman TUR">等待马达开启时间</FONT></TD></TR></TBODY></TABLE></P>
<P><FONT face="Times New Roman TUR" 
size=3>从软盘读取数据,不能够跨越磁道,即每次读取,尽管可以同时读取多个扇区,而这些扇区却必须都属于同一个磁道。BIOS 
13h服务例程将对此进行验证,如果发现用户所要读取扇区跨越了不同的磁道,则返回调用失败。而验证所依据的数据则是软盘参数表。假如,软盘参数表中所记录的“每磁道的扇区数”(偏移量为4的位置)为9;如果现在一个INT 
13h, ax = 2的调用指定:磁头为0,磁道为1,磁道内起始扇区为2,要读取的扇区数目为9;由于磁道内起始扇区+要读取的扇区数-1 = 2+9 -1 = 
10 〉9,则调用将会失败。(之所以减去1是因为磁道内起始扇区是从1开始计数的,而不是0)。</FONT></P>

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