NEC uPD78P078 - Manual (Page 538)

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CHAPTER 23 EXTERNAL DEVICE EXPANSION FUNCTION
Figure 23-8. External Memory Read Modify Write Timing in Multiplexed 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
ASTB
RD
WR
AD0 to AD7
A8 to A15
Lower Address Write Data
Higher Address
Hi-Z
Read Data
Lower Address
Higher Address
Internal Wait Signal
(1-clock wait)
Hi-Z
ASTB
RD
WR
AD0 to AD7
A8 to A15
Write Data Read Data
ASTB
RD
WR
Higher Address
AD0 to AD7
A8 to A15
WAIT
Hi-Z
Lower Address Write Data Read Data