Table 5-2 Exception Vector Assignments
Vector
Vector Offset
Space
Assignment
Number
Dec
0
Hex
000
004
008
00C
010
014
018
01C
020
024
028
02C
030
034
038
03C
0
1
SP
SP
SD
SD
SD
SD
SD
SD
SD
SD
SD
SD
SD
SD
SD
SD
SD
Reset: Initial Stack Pointer
Reset: Initial Program Counter
Bus Error
4
2
8
3
12
16
20
24
28
32
36
40
44
48
52
56
60
Address Error
4
Illegal Instruction
5
Zero Division
6
CHK, CHK2 Instructions
TRAPcc, TRAPV Instructions
Privilege Violation
7
8
9
Trace
10
11
12
13
14
15
16–23
Line 1010 Emulator
Line 1111 Emulator
Hardware Breakpoint
(Reserved, Coprocessor Protocol Violation)
Format Error and Uninitialized Interrupt
Format Error and Uninitialized Interrupt
(Unassigned, Reserved)
5
64
92
040
05C
24
25
96
060
064
068
06C
070
074
078
07C
SD
SD
SD
SD
SD
SD
SD
SD
SD
Spurious Interrupt
100
104
108
112
116
120
124
Level 1 Interrupt Autovector
Level 2 Interrupt Autovector
Level 3 Interrupt Autovector
Level 4 Interrupt Autovector
Level 5 Interrupt Autovector
Level 6 Interrupt Autovector
Level 7 Interrupt Autovector
Trap Instruction Vectors (0–15)
26
27
28
29
30
31
32–47
128
188
080
0BC
48–58
59–63
64–255
192
232
0C0
0E8
SD
SD
SD
(Reserved, Coprocessor)
(Unassigned, Reserved)
User Defined Vectors (192)
236
252
0EC
0FC
256
1020
100
3FC
Each vector is assigned an 8-bit number. Vector numbers for some exceptions are ob-
tained from an external device; others are supplied by the processor. The processor
multiplies the vector number by four to calculate vector offset, then adds the offset to
the contents of the VBR. The sum is the memory address of the vector.
5.9.2 Types of Exceptions
An exception can be caused by internal or external events.
An internal exception can be generated by an instruction or by an error. The TRAP,
TRAPcc, TRAPV, BKPT, CHK, CHK2, RTE, and DIV instructions can cause excep-
tions during normal execution. Illegal instructions, instruction fetches from odd ad-
dresses, word or long-word operand accesses from odd addresses, and privilege
violations also cause internal exceptions.
MOTOROLA
5-16
CENTRAL PROCESSING UNIT
MC68331
USER’S MANUAL
MOTOROLA [ MOTOROLA ]
