hw/i386.reference/c09.htm

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   4 <TITLE>80386 Programmer's Reference Manual -- Chapter 09</TITLE>
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  13 <P>
  14 <H1>Chapter 9  Exceptions and Interrupts</H1>
  15 <P>
  16 Interrupts and exceptions are special kinds of control transfer; they work
  17 somewhat like unprogrammed
  18 <A HREF="CALL.htm">CALL</A>s. They alter the normal program flow to
  19 handle external events or to report errors or exceptional conditions. The
  20 difference between interrupts and exceptions is that interrupts are used to
  21 handle asynchronous events external to the processor, but exceptions handle
  22 conditions detected by the processor itself in the course of executing
  23 instructions.
  24 <P>
  25 There are two sources for external interrupts and two sources for
  26 exceptions:
  27 <OL>
  28 <LI>Interrupts
  29 <UL>
  30 <LI>Maskable interrupts, which are signalled via the INTR pin.
  31
  32 <LI>Nonmaskable interrupts, which are signalled via the NMI
  33          (Non-Maskable Interrupt) pin.
  34 </UL>
  35 <LI>Exceptions
  36 <UL>
  37 <LI>Processor detected. These are further classified as faults, traps,
  38          and aborts.
  39
  40 <LI>Programmed. The instructions
  41 <A HREF="INT.htm">INTO</A>,
  42 <A HREF="INT.htm">INT</A> 3,
  43 <A HREF="INT.htm">INT n</A>, and
  44 <A HREF="BOUND.htm">BOUND</A> can
  45          trigger exceptions. These instructions are often called "software
  46          interrupts", but the processor handles them as exceptions.
  47 </UL>
  48 </OL>
  49 This chapter explains the features that the 80386 offers for controlling
  50 and responding to interrupts when it is executing in protected mode.
  51 <P>
  52 <A HREF="s09_01.htm">9.1  Identifying Interrupts</A><BR>
  53 <A HREF="s09_02.htm">9.2  Enabling and Disabling Interrupts</A><BR>
  54 <A HREF="s09_03.htm">
  55 9.3  Priority Among Simultaneous Interrupts and Exceptions</A><BR>
  56 <A HREF="s09_04.htm">9.4  Interrupt Descriptor Table</A><BR>
  57 <A HREF="s09_05.htm">9.5  IDT Descriptors</A><BR>
  58 <A HREF="s09_06.htm">9.6  Interrupt Tasks and Interrupt Procedures</A><BR>
  59 <A HREF="s09_07.htm">9.7  Error Code</A><BR>
  60 <A HREF="s09_08.htm">9.8  Exception Conditions</A><BR>
  61 <A HREF="s09_09.htm">9.9  Exception Summary</A><BR>
  62 <A HREF="s09_10.htm">9.10  Error Code Summary</A>
  63 <P>
  64 <HR>
  65 <P>
  66 <B>up:</B> <A HREF="toc.htm">
  67 Table of Contents</A><BR>
  68 <B>prev:</B> <A HREF="s08_03.htm">8.3  Protection and I/O</A><BR>
  69 <B>next:</B> <A HREF="s09_01.htm">9.1  Identifying Interrupts</A>
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