at89c51ac3-s3sim ATMEL Corporation, at89c51ac3-s3sim Datasheet - Page 52

• Manufacturer Part Number: at89c51ac3-s3sim
• Description: At89c51ac3 Enhanced 8-bit Microcontroller With 64kb Flash Memory
• Manufacturer: ATMEL Corporation

52
AT89C51AC3
Table 17. Program Lock Bit
Program Lock bits
U: unprogrammed
P: programmed
WARNING: Security level 2 and 3 should only be programmed after Flash and Core
verification.
Security
level
1
2
3
4
Program Lock Bits
LB0
U
P
U
U
LB1
U
U
P
U
LB2
U
U
U
P
Protection Description
No program lock features enabled.
MOVC instruction executed from external program memory are
disabled from fetching code bytes from internal memory, EA is sampled
and latched on reset, and further parallel programming of the Flash is
disabled.
ISP and software programming with API are still allowed.
Writing EEprom Data from external parallel programmer is disabled but
still allowed from internal code execution.
Same as 2, also verify through parallel programming interface is
disabled.
Writing And Reading EEPROM Data from external parallel programmer
is disabled but still allowed from internal code execution..
Same as 3, also external execution is disabled
4383D–8051–02/08