NEC uPD78P078 User Manual

Page 540

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540

CHAPTER 23 EXTERNAL DEVICE EXPANSION FUNCTION

Figure 23-9. Instruction Fetch from External Memory in Separate Bus Mode

(a) No wait (PW1, PW0 = 0, 0) setting

(b) Wait (PW1, PW0 = 0, 1) setting

(c) External wait (PW1, PW0 = 1, 1) setting

Note

In the separate bus mode, use of the address strobe signal is not required though it is output from

the ASTB/P67 pin.

ASTB

Note

RD

AD0 to AD7

A0 to A7

A8 to A15

Lower Address

Operation Code

Higher Address

Lower Address

ASTB

Note

RD

AD0 to AD7

A0 to A7

A8 to A15

Lower Address

Operation Code

Higher Address

Lower Address

Internal Wait Signal

(1-clock wait)

ASTB

Note

RD

Lower Address

Operation Code

Higher Address

Lower Address

AD0 to AD7

A0 to A7

A8 to A15

WAIT

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