w78e051c Winbond Electronics Corp America, w78e051c Datasheet - Page 10

• Manufacturer Part Number: w78e051c
• Description: 8-bit Microcontroller
• Manufacturer: Winbond Electronics Corp America

6. SECURITY BITS
During the programmer operation mode, the Flash EPROM can be programmed and verified
repeatedly. Until the code inside the Flash EPROM is confirmed OK, the code can be protected. The
protection of Flash EPROM and those operations on it are described below. The W78E051C has a
Special Setting Register, the Security Register, which can be accessed in normal mode. The register
can only be accessed from the Flash EPROM operation mode. Those bits of the Security Registers
can not be changed once they have been programmed from high to low. They can only be reset
through erase-all operation. The Security Register is addressed in the Flash EPROM operation mode
by address #0FFFFh.
6.1 Lock Bit
This bit is used to protect the customer's program code in the W78E051C. It may be set after the
programmer finishes the programming and verifies sequence. Once this bit is set to logic 0, both the
on-chip ROM data and Special Setting Registers can not be accessed again.
Default 1 for all security bits.
D7 D6 D5 D4 D3 D2 D1 D0
B2 : Encryption
B0 : Lock bit, logic 0 : active
B1 : MOVC inhibit,
B7 : Osillator Control
B7
logic 1 : Full gain
logic 0 : 1/2 gain
logic 0 : the encryption logic enable
logic 1 : the encryption logic disable
logic 0 : the MOVC instruction in external memory
logic 1 : no restriction.
Reserved
cannot access the code in internal memory.
B2
B1
B0
Reserved bits must be kept in logic 1.
Special Setting Register
Security Bits
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W78E51C/W78E051C
4KB Flash EPROM
Program Memory
Security Register
Reserved
0FFFFh
0000h
0FFFh