Intel IA-32 User Manual

Page 558

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15-8 Vol. 3A

8086 EMULATION

Table 15-1. Real-Address Mode Exceptions and Interrupts

Vector

No.

Description

Real-Address

Mode

Virtual-8086

Mode

Intel 8086

Processor

0

Divide Error (#DE)

Yes

Yes

Yes

1

Debug Exception (#DB)

Yes

Yes

No

2

NMI Interrupt

Yes

Yes

Yes

3

Breakpoint (#BP)

Yes

Yes

Yes

4

Overflow (#OF)

Yes

Yes

Yes

5

BOUND Range Exceeded (#BR)

Yes

Yes

Reserved

6

Invalid Opcode (#UD)

Yes

Yes

Reserved

7

Device Not Available (#NM)

Yes

Yes

Reserved

8

Double Fault (#DF)

Yes

Yes

Reserved

9

(Intel reserved. Do not use.)

Reserved

Reserved

Reserved

10

Invalid TSS (#TS)

Reserved

Yes

Reserved

11

Segment Not Present (#NP)

Reserved

Yes

Reserved

12

Stack Fault (#SS)

Yes

Yes

Reserved

13

General Protection (#GP)*

Yes

Yes

Reserved

14

Page Fault (#PF)

Reserved

Yes

Reserved

15

(Intel reserved. Do not use.)

Reserved

Reserved

Reserved

16

Floating-Point Error (#MF)

Yes

Yes

Reserved

17

Alignment Check (#AC)

Reserved

Yes

Reserved

18

Machine Check (#MC)

Yes

Yes

Reserved

19-31

(Intel reserved. Do not use.)

Reserved

Reserved

Reserved

32-255

User Defined Interrupts

Yes

Yes

Yes

NOTE:

* In the real-address mode, vector 13 is the segment overrun exception. In protected and virtual-8086

modes, this exception covers all general-protection error conditions, including traps to the virtual-
8086 monitor from virtual-8086 mode.

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