Single-Chip Microcontrollers User's Manual

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CHAPTER 22 EXTERNAL DEVICE EXPANSION FUNCTION
ASTB
RD
Lower Address Operation CodeAD0 to AD7
A8 to A15
Higher Address
WAIT
ASTB
RD
AD0 to AD7
A8 to A15
Lower Address Operation Code
Higher Address
Internal Wait Signal
(
1-clock wait
)
ASTB
RD
AD0 to AD7
A8 to A15
Lower Address Operation Code
Higher Address
Figure 22-4. Instruction Fetch from External Memory
(a) No wait (PW1, PW0 = 0, 0) setting
(b) Wait (PW1, PW0 = 0, 1) setting
(c) External wait (PW1, PW0 = 1, 1) setting