W79E532A Datasheet, PDF (58/78 Pages) Winbond – 8-BIT MICROCONTROLLER

W79E532A/W79L532A
Example 4: Invalid access
MOV
MOV
NOP
NOP
CLR
TA, #0AAh
TA, #055h
POR
Example 5: Invalid Access
MOV
NOP
MOV
SETB
TA, #0AAh
TA, #055h
EWT
3 M/C
3 M/C
1 M/C
1 M/C
2 M/C
3 M/C
1 M/C
3 M/C
2 M/C
In the first three examples, the writing to the protected bits is done before the 3 machine cycle window
closes. In Example 4, however, the writing to the protected bit occurs after the window has closed,
and so there is effectively no change in the status of the protected bit. In Example 5, the second write
to TA occurs 4 machine cycles after the first write, therefore the timed access window in not opened at
all, and the write to the protected bit fails.
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