89C51 Datasheet, PDF (27/32 Pages) NXP Semiconductors – 80C51 8-bit microcontroller family 4K/8K/16K/32K Flash

Philips Semiconductors
80C51 8-bit microcontroller family
4K/8K/16K/32K Flash
Product specification
89C51/89C52/89C54/89C58
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 89C51/89C52/89C54/89C58 has 3
programmable security lock bits that will provide different levels of
protection for the on-chip code and data (see Table 8). Unlike the
ROM and OTP versions, the security lock bits are independent. LB3
includes the security protection of LB1.
Table 8.
SECURITY LOCK BITS¹
Level
PROTECTION DESCRIPTION
LB1
MOVC instructions executed from external program memory are disabled from fetching code bytes from
internal memory.
LB2
Program verification is disabled
LB3
External execution is disabled.
NOTE:
1. The security lock bits are independent.
1999 Oct 27
27