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FIGURE 25 – EXTERNAL DATA MEMORY READ CYCLE
Parameter
min
typ
max
units
ALE
nPSEN
nRD
PORT 0
PORT 2
A0 - A7
DATA IN
A8 - A15 FROM DPH
t1
t2
t3
t4
t5
t6
t7
t8
t9
t10
t11
t12
t13
t1
t2
t3
t4
t5
t6
t7
t8
t9
t10
t11
t12
t13
ALE Pulse Width
ALE Low to Valid Data In
ALE Low to nRD or nWR Low
nRD or nWR High to ALE High
nRD Pulse Width
Address Valid to ALE Low
Address to Valid Data In
nRD Low to Address Float
nRD Low to Valid Data In
Data Hold after nRD
Data Float after nRD
Address Valid to nRD or nWR Low
Address Hold after ALE Low
85
137.5
22.5
275
7
0
120
27
350
238.5
102.5
397.5
0
147.5
55
nS
nS
nS
nS
nS
nS
nS
nS
nS
nS
nS
nS
nS
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