Philips Semiconductors

Preliminary data

P89C668

80C51 8-bit Flash microcontroller family

64KB ISP Flash with 8KB RAM

2001 Jul 27

51

Security

The security feature protects against software piracy and prevents the contents of the Flash from being read. The Security Lock bits are located

in Flash. The P89C668 has 3 programmable security lock bits that will provide different levels of protection for the on-chip code and data (see

Table 11).

Table 11.

PROTECTION DESCRIPTION

Level

LB1

LB2

LB3

PROTECTION DESCRIPTION

1

0

0

0

MOVC instructions executed from external program memory are disabled from fetching

code bytes from internal memory.

2

1

0

0

Same as level 1, plus block erase is disabled. Erase or programming of the status byte or

boot vector is disabled.

3

1

1

0

Same as level 2, plus verify of code memory is disabled.

4

1

1

1

Same as level 3, plus external execution is disabled.

NOTE:

1. Security bits are independent of each other. Full-chip erase may be performed regardless of the state of the security bits.

2. All other combination of lockbits is undefined.

3. Setting LBx doesn’t prevent programming of unprogrammed bits.