Figure 4-5. Exception Vector Format; Figure 4-6. Address Translated From 8-Bit Vector Number - Motorola MC68306 User Manual

WORD 0
WORD 1
A31

Figure 4-6. Address Translated from 8-Bit Vector Number

The actual address on the address bus is truncated to the number of address bits
available on the bus of the particular implementation of the M68000 architecture. In the
EC000 core, this is 24 address bits. The memory map for exception vectors is shown in
Table 4-5.
The vector table is 512 words long (1024 bytes), starting at address 0 (decimal) and
proceeding through address 1023 (decimal). The vector table provides 255 unique
vectors, some of which are reserved for trap and other system function vectors. Of the
255, 192 are reserved for user interrupt vectors. However, the first 64 entries are not
protected, so user interrupt vectors may overlap at the discretion of the systems designer.
MOTOROLA
EVEN BYTE (A0=0)
NEW PROGRAM COUNTER (HIGH)
NEW PROGRAM COUNTER (LOW)

Figure 4-5. Exception Vector Format

ALL ZEROES
MC68306 USER'S MANUAL
ODD BYTE (A0=0)
A10
v7 v6 v5 v4 v3
A1=0
A1=1
EC30
A0
v2 v1 v0 0 0
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