Datasheet
47
T89C51AC2
4127D–8051–02/03
Hardware Security Byte Table 27. Hardware Security Byte
Default value after erasing chip: FFh
Notes: 1. Only the 4 MSB bits can be accessed by software.
2. The 4 LSB bits can only be accessed by parallel mode.
76543210
X2B BLJB - - - LB2 LB1 LB0
Bit
Number
Bit
Mnemonic Description
7X2B
X2 Bit
Set this bit to start in standard mode.
Clear this bit to start in X2 mode.
6BLJB
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.
5-3 -
Reserved
The value read from these bits are indeterminate.
2-0 LB2:0 Lock Bits