W77C58 Datasheet, PDF (37/71 Pages) Winbond – 8 BIT MICROCONTROLLER

Preliminary W77C58
the stretching of the instruction only results in the elongation of the MOVX instruction, as if the state
of the CPU was held for the desired period. There is no effect on any other instruction or its timing. By
default, the Stretch value is set at 1, giving a MOVX instruction of 3 machine cycles. If desired by the
user the stretch value can be set to 0 to give the fastest MOVX instruction of only 2 machine cycles.
Table 4. Data Memory Cycle Stretch Values
M2
M1
M0
Machine
Cycles
/RD or /WR
strobe width
/RD or /WR /RD or /WR
strobe width strobe width
in Clocks
@25 MHz @40 MHz
0
0
0
2
2
80 nS
50 nS
0
0
1
3(default)
4
160 nS
100 nS
0
1
0
4
8
320 nS
200 nS
0
1
1
5
12
480 nS
300 nS
1
0
0
6
16
640 nS
400 nS
1
0
1
7
20
800 nS
500 nS
1
1
0
8
24
960 nS
600 nS
1
1
1
9
28
1120 nS
700 nS
CLK
ALE
PSEN
WR
PORT 0
PORT 2
Last Cycle
of Previous
Instruction
First
Machine cycle
Second
Machine cycle
MOVX instruction cycle
Next Instruction
Machine Cycle
C1 C2 C3 C4 C1 C2 C3 C4 C1 C2 C3 C4 C1 C2 C3 C4
A0-A7
D0-D7
A0-A7
D0-D7
A0-A7
D0-D7
A0-A7
D0-D7
MOVX Inst.
Address
Next Inst.
Address
MOVX Data
Address
MOVX Inst.
Next Inst. Read ^{MOVX Data out}
A15-A8
A15-A8
A15-A8
A15-A8
Figure 8: Data Memory Write with Stretch Value = 0
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Publication Release Date: September 1999
Revision A1