W77C32 Datasheet, PDF (66/78 Pages) Winbond – 8 BIT MICROCONTROLLER

W77C32/W77C032A
Example 4: Invalid Access
MOV TA, #0Aah 3 M/C
NOP
1 M/C
MOV TA, #055h 3 M/C
SETB EWT
2 M/C
In the first two examples, the writing to the protected bits is done before the 3 machine cycle window
closes. In Example 3, 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 4, 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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