Figure 3-4. Scc1 Vector Calculation Example; Table 3-5. Encoding The Interrupt Vector - Motorola MC68302 User Manual

Priority
7 (Highest)
6
5
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
3
2
1 (Lowest)
1. FORMULATE 8-BIT VECTOR
2. MULTIPLY BY 4 TO GET ADDRESS
3. READ 32-BIT VALUE AT $2B4 AND JUMP
MOTOROLA

Table 3-5. Encoding the Interrupt Vector

5-Bit
Level Vector
10111
10110
None
01111
01110
01101
01100
01011
01010
01001
01000
00111
00110
00101
00100
00011
00010
00001
00000
None
None
10001
V7–V5 5-BIT VECTOR
1 0 1 0 1 1 0 1
1 0 1 0 1 1 0 1 0 0 = $2B4
$2B4 0007
$2B6 0302

Figure 3-4. SCC1 Vector Calculation Example

MC68302 USER'S MANUAL
Interrupt Source
External Device
External Device
External Device
General-Purpose Interrupt 3 (PB11)
General-Purpose Interrupt 2 (PB10)
SCC1
SDMA Channels Bus Error
IDMA Channel
SCC2
Timer 1
SCC3
General-Purpose Interrupt 1 (PB9)
Timer 2
SCP
Timer 3
SMC1
SMC2
General-Purpose Interrupt 0 (PB8)
Error
External Device
External Device
External Device
V7–V5 PROGRAMMED BY SOFTWARE IN
THE GIMR.
5-BIT VECTOR FROM TABLE 3-4.
NOTE THAT $2B4 IS IN THE USER
INTERRUPT VECTOR AREA OF THE
EXCEPTION VECTOR TABLE. V7–V5 WAS
PURPOSELY CHOSEN TO CAUSE THIS.
INTERRUPT HANDLER BEGINS AT
$070302 (24-BIT ADDRESSES ARE USED
ON THE M68000).
System Integration Block (SIB)
3-23