at89c51ac3-s3sim ATMEL Corporation, at89c51ac3-s3sim Datasheet - Page 59

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

Hardware Security Byte
4383D–8051–02/08
Table 24. Hardware Security Byte
Default value after erasing chip: FFh
Notes:
Number
X2B
Bit
5-3
2-0
7
7
6
1. Only the 4 MSB bits can be accessed by software.
2. The 4 LSB bits can only be accessed by parallel mode.
Mnemonic Description
BLJB
LB2:0
BLJB
X2B
Bit
6
-
X2 Bit
Set this bit to start in standard mode
Clear this bit to start in X2 mode.
Boot Loader JumpBit
- 1: To start the user’s application on next RESET (@0000h) located in FM0,
- 0: To start the boot loader(@F800h) located in FM1.
Reserved
The value read from these bits are indeterminate.
Lock Bits
5
-
4
-
3
-
LB2
2
LB1
1
LB0
0
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