at89c51rd2-smsum ATMEL Corporation, at89c51rd2-smsum Datasheet - Page 96

• Manufacturer Part Number: at89c51rd2-smsum
• Description: 8-bit Flash Microcontroller
• Manufacturer: ATMEL Corporation

96
AT89C51RD2/ED2
After programming the part by ISP, the BSB must be cleared (00h) in order to allow the applica-
tion to boot at 0000h.
The content of the Software Security Byte (SSB) is described in Table 24-4 and Table 24-5.
To assure code protection from a parallel access, the HSB must also be at the required level.
Table 24-4.
The two lock bits provide different levels of protection for the on-chip code and data, when pro-
grammed as shown in Table 24-5.
Mnemonic
Number
1-0
BSB
SSB
Bit
7
6
5
4
3
2
7
-
Mnemonic
Definition
Boot Status Byte
Software Security Byte
Copy of the Manufacturer Code
Copy of the Device ID #1: Family Code
Copy of the Device ID #2: Memories Size and
Type
Copy of the Device ID #3: Name and Revision
Software Security Byte
LB1-0
Bit
6
-
-
-
-
-
-
-
Description
Reserved
Do not clear this bit.
Reserved
Do not clear this bit.
Reserved
Do not clear this bit.
Reserved
Do not clear this bit.
Reserved
Do not clear this bit.
Reserved
Do not clear this bit.
User Memory Lock Bits
See
Table 24-5
5
-
4
-
3
-
Default value
0FFh
ECh
FFh
D7h
EFh
58h
2
-
Atmel
C51 X2, Electrically Erasable
AT89C51RD2/ED2 64KB
AT89C51RD2/ED2 64KB,
Revision 0
LB1
Description
1
4235J–8051–01/08
LB0
0