Typewriter User Manual

MOTOROLA MC68340 USER’S MANUAL 5- 39
5.5.1 Exception Vectors
An exception vector is the address of a routine that handles an exception. The VBR
contains the base address of a 1024-byte exception vector table, which consists of 256
exception vectors. Sixty-four vectors are defined by the processor, and 192 vectors are
reserved for user definition as interrupt vectors. Except for the reset vector which is two
long words, each vector in the table is one long word. Refer to Table 5-16 for information
on vector assignment.
Table 5-16. Exception Vector Assignments
Vector Offset
Vector Number Dec Hex Space Assignment
0 0 000 SP Reset: Initial Stack Pointer
1 4 004 SP Reset: Initial Program Counter
2 8 008 SD Bus Error
3 12 00C SD Address Error
4 16 010 SD Illegal Instruction
5 20 014 SD Zero Division
6 24 018 SD CHK, CHK2 Instructions
7 28 01C SD TRAPcc, TRAPV Instructions
8 32 020 SD Privilege Violation
9 36 024 SD Trace
10 40 028 SD Line 1010 Emulator
11 44 02C SD Line 1111 Emulator
12 48 030 SD Hardware Breakpoint
13 52 034 SD (Reserved for Coprocessor Protocol Violation)
14 56 038 SD Format Error
15 60 03C SD Uninitialized Interrupt
16–23 64
92
040
05C
SD (Unassigned, Reserved)
—
24 96 060 SD Spurious Interrupt
25 100 064 SD Level 1 Interrupt Autovector
26 104 068 SD Level 2 Interrupt Autovector
27 108 06C SD Level 3 Interrupt Autovector
28 112 070 SD Level 4 Interrupt Autovector
29 116 074 SD Level 5 Interrupt Autovector
30 120 078 SD Level 6 Interrupt Autovector
31 124 07C SD Level 7 Interrupt Autovector
32–47 128
188
080
0BC
SD Trap Instruction Vectors (0–15)
—
48–58 192
232
0C0
0E8
SD (Reserved for Coprocessor)
—
59–63 236
252
0EC
0FC
SD (Unassigned, Reserved)
—
64–255 256
1020
100
3FC
SD User-Defined Vectors (192)
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