
MOTOROLA
6-2
EXCEPTION PROCESSING
CPU32
REFERENCE MANUAL
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.
6.1.2 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.
Table 6-1 Exception Vector Assignments
Vector
Number
Vector Offset
Hex
000
004
008
00C
010
014
018
01C
020
024
028
02C
030
034
038
03C
040
05C
060
064
068
06C
070
074
078
07C
080
0BC
0C0
0E8
0EC
0FC
100
3FC
Assignment
Dec
0
4
8
12
16
20
24
28
32
36
40
44
48
52
56
60
64
92
96
100
104
108
112
116
120
124
128
188
192
232
236
252
256
1020
Space
SP
SP
SD
SD
SD
SD
SD
SD
SD
SD
SD
SD
SD
SD
SD
SD
SD
0
1
2
3
4
5
6
7
8
9
Reset: Initial Stack Pointer
Reset: Initial Program Counter
Bus Error
Address Error
Illegal Instruction
Zero Division
CHK, CHK2 Instructions
TRAPcc, TRAPV Instructions
Privilege Violation
Trace
Line 1010 Emulator
Line 1111 Emulator
Hardware Breakpoint
(Reserved, Coprocessor Protocol Violation)
Format Error and Uninitialized Interrupt
Format Error and Uninitialized Interrupt
10
11
12
13
14
15
16–23
(Unassigned, Reserved)
24
25
26
27
28
29
30
31
SD
SD
SD
SD
SD
SD
SD
SD
SD
Spurious Interrupt
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
32–47
Trap Instruction Vectors (0–15)
48–58
SD
(Reserved, Coprocessor)
59–63
SD
(Unassigned, Reserved)
64–255
SD
User Defined Vectors (192)
F
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