Datasheet

41
4337K–USB–04/08
AT89C5130A/31A-M
Table 9-3. Software Registers
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 9-4 and Table 9-5.
To assure code protection from a parallel access, the HSB must also be at the required level.
The two lock bits provide different levels of protection for the on-chip code and data, when pro-
grammed as shown to Table 9-5.
Address Mnemonic Description Default value
01 SBV Software Boot Vector FFh –
00 BSB Boot Status Byte 0FFh –
05 SSB Software Security Byte FFh –
30 –
Copy of the Manufacturer
Code
58h Atmel
31 –
Copy of the Device ID #1:
Family Code
D7h
C51 X2, Electrically
Erasable
60 –
Copy of the Device ID #2:
Memories
F7h
AT89C5130A/31A-M 32
Kbyte
61 –
Copy of the Device ID #3:
Name
DFh
AT89C5130A/31A-M 32
Kbyte, revision 0
Table 9-4. Software Security Byte (SSB)
7 6 5 4 3 2 1 0
- - - - - - LB1 LB0
Bit
Number
Bit
Mnemonic Description
7 -
Reserved
Do not clear this bit.
6 -
Reserved
Do not clear this bit.
5 -
Reserved
Do not clear this bit.
4 -
Reserved
Do not clear this bit.
3 -
Reserved
Do not clear this bit.
2 -
Reserved
Do not clear this bit.
1-0 LB1-0
User Memory Lock Bits
See Table 9-5