EXCEPTION PROCESSING STATE (INTERRUPT PROCESSING)
7 - 28 PROCESSING STATES MOTOROLA
ii1
ii2
MAIN
PROGRAM
MEMORY
n1
INTERRUPT SYNCHRONIZED
AND RECOGNIZED
AS PENDING
ADDITIONAL INTERRUPTS
DISABLED DURING
FAST INTERRUPT
INTERRUPTS
RE-ENABLED
ii = INTERRUPT INSTRUCTION
n = NORMAL INSTRUCTION
n2
n3
n4
n5
n6
n7
n8
n9
ADDITIONAL INTERRUPTS
DISABLED DURING
FAST INTERRUPT
INTERRUPTS
RE-ENABLED
FOUR INSTRUCTION
DECODES ii1
ii2
(a) Instruction Fetches from Memory
INTERRUPT CONTROL CYCLE 1 ii
INTERRUPT CONTROL CYCLE 2 ii
FETCH n1 n2 ii1 ii2 n3 n4 n5 n6 ii1 ii2
DECODE n1 n2 ii1 ii2 n3 n4 n5 n6 ii1 ii2
EXECUTE n1 n2 ii1 ii2 n3 n4 n5 n6 ii1 ii2
INSTRUCTION CYCLE COUNT 12345 6 789101112

i = INTERRUPT

ii = INTERRUPT INSTRUCTION WORD

n = NORMAL INSTRUCTION WORD

INTERRUPT SYNCHRONIZED AND
RECOGNIZED AS PENDING
INTERRUPTS RE-ENABLED
6 Icyc
(b) Program Controller Pipeline
Figure 7-9 Two Consecutive Fast Interrupts