DS89C420_02 Datasheet, PDF (27/58 Pages) Maxim Integrated Products – Ultra-High-Speed Microcontroller

DS89C420
Figure 6. PAGE MODE 1, EXTERNAL MEMORY CYCLE (CD1:CD0 = 10)
Internal Memory Cycles
XTAL1
ALE
PSEN
RD / WR
Port 0
External Memory Cycles
Inst Inst ^{MOVX MOVX}
Data
Inst
Data
PAGES=00
Port 2
ALE
MSB LSB LSB LSB LSB MSB LSB
Page Miss
Page Hit
Data Access
MOVX executed
MSB LSB MSB LSB MSB
Page Miss Data Access
MOVX executed
PSEN
RD / WR
Port 0
Port 2
ALE
PSEN
RD / WR
Port 0
Port 2
MOVX
Inst
Data
PAGES=01
MSBAdd
LSB Add
Page Miss
LSB Add
MSBAdd
LSB Add
Page Hit
Data Access
MOVX executed
MSBAdd
Page Miss
next instruction
MSBAdd
Page Miss
Inst
LSB Add
Data
LSB Add
Data Access
PAGES=10
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