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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