MC68020 Motorola, MC68020 Datasheet - Page 218

• Manufacturer Part Number: MC68020
• Description: (MC68020 / MC68EC020) MICROPROCESSORS USERS MANUAL
• Manufacturer: Motorola

8.1.5 Instruction Stream Timing Examples
A programming example allows a more detailed examination of these effects. The effect of
instruction execution overlap on instruction timing is illustrated by the following example
instruction stream.
Example 1
For the first example, the assumptions are:
For example 1, the instruction stream is positioned in 32-bit memory as follows:
Figure 8-3 shows processor activity on the first example instruction stream. It shows the
activity of the external bus, the bus controller, the sequencer, and the attributed instruction
execution time.
8-4
1. The data bus is 32 bits,
2. The first instruction is prefetched from an odd-word address,
3. Memory access occurs with no wait states, and
4. The instruction cache is disabled.
Address
#1) MOVE.L
#2) ADD.L
#3) MOVE.L
#4) ADD.L
M68020 USER’S MANUAL
n + 4
n + 8
n
Instruction
(A1), –(A2)
D4,(A1)+
D4,D5
D5,D6
ADD #2
ADD #4
•••
MOVE #1
MOVE #3
•••
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