CENTRAL PROCESSING UNIT
MC68332
5-14
USER’S 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.
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.
Table 5-2 Exception Vector Assignments
Vector
Vector Offset
Assignment
Number
Dec
Hex
Space
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, Coprocessor Protocol Violation)
14
56
038
SD
Format Error and Uninitialized Interrupt
15
60
03C
SD
Format Error and 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, 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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