W79E225A_08 Datasheet, PDF (190/203 Pages) Winbond – 8-bit Microcontroller

Preliminary W79E225A/226A/227A Data Sheet
MOVX Characteristics Using Stretch Memory Cycle, continud
PARAMETER
SYMBOL
VARIABLE
CLOCK
MIN.
VARIABLE
CLOCK
MAX.
UNITS STRECH
Port 2 Address to RD or WR
Low
t_AVWL2
1.5t_CLCL - 5
2.5t_CLCL - 5
nS
t_MCS = 0
t_MCS>0
Data Valid to WR Transition t_QVWX
-5
1.0t_CLCL - 5
nS
t_MCS = 0
t_MCS>0
Data Hold after Write
t_WHQX
t_CLCL - 5
2.0t_CLCL - 5
nS
t_MCS = 0
t_MCS>0
RD Low to Address Float
t_RLAZ
0.5t_CLCL - 5
nS
RD or WR high to ALE high ^tWHLH
0
10
nS
1.0t_CLCL - 5
1.0t_CLCL + 5
t_MCS = 0
t_MCS>0
Note: t_MCS is a time period related to the Stretch memory cycle selection. The following table shows the time period of t_MCS
for each selection of the Stretch value.
M2
M1
M0
0
0
0
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
MOVX CYCLES
2 machine cycles
3 machine cycles
4 machine cycles
5 machine cycles
6 machine cycles
7 machine cycles
8 machine cycles
9 machine cycles
T_MCS
0
4 t_CLCL
8 t_CLCL
12 t_CLCL
16 t_CLCL
20 t_CLCL
24 t_CLCL
28 t_CLCL
Explanation of Logics Symbols
In order to maintain compatibility with the original 8051 family, this device specifies the same
parameter for each device, using the same symbols. The explanation of the symbols is as follows.
t
Time
A
Address
C
Clock
D
Input Data
H
Logic level high
L
Logic level low
I
Instruction
P
PSEN
Q
Output Data
R
RD signal
V
Valid
X
No longer a valid state
W
WR signal
Z
Tri-state
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Publication Release Date: April 15, 2008
Revision A4.0