w77e58 Winbond Electronics Corp America, w77e58 Datasheet - Page 74

• Manufacturer Part Number: w77e58
• Description: 8 Bit Microcontroller
• Manufacturer: Winbond Electronics Corp America

SECURITY BITS
During the on-chip MTP ROM operation mode, the MTP ROM can be programmed and verified
repeatedly. Until the code inside the MTP ROM is confirmed OK, the code can be protected. The
protection of MTP ROM and those operations on it are described below.
The W77E58 has several Special Setting Registers, including the Security Register and
Company/Device ID Registers, which can not be accessed in normal mode. These registers can only
be accessed from the MTP ROM 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 contents of the Company ID and Device ID registers have been set in factory. Both
registers are addressed by the A0 address line during the same specific condition.
The Security Register is addressed in the MTP-ROM operation mode by address #0FFFFh.
D7 D6 D5 D4 D3 D2 D1 D0
B0 : Lock bit, logic 0 : active
B1 : MOVC inhibit,
B2 : Seed 0 & 1 access inhibit
Default 1 for each bit.
1 1 0 1 1 0 1 0
0 1 1
Reserved
logic 0 : the MOVC instruction in external memory
logic 1 : no restriction.
0
cannot access the code in internal memory.
0 0
B2
B1
1 0
B0
Special Setting Registers
Company ID (#DAH)
Device ID (#62H)
Security Bits
- 74 -
Preliminary W77E58
32KB MTP ROM
Program Memory
Security Register
On-Chip
Reserved
Seed 1
Seed 0
0FF3Fh
0FF7Fh
0FFFFh
0000h
7FFFh