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M16C/64C Group
30.4
Optional Function Select Area
In an option function select area, the MCU state after reset and the function to prevent rewrite in parallel
I/O mode are selected.
The option function select area is not an SFR, and therefore cannot be rewritten by a program. Set an
appropriate value when writing a program to the flash memory. The entire option function select area
becomes FFh when the block including the option function select area is erased.
In blank products, the OFS1 address value is FFh when shipped. After a value is written by the user, this
address takes on the written value. In programmed products, the OFS1 address is the value set in the
user program prior to shipping.
Selection using the optional function select area can be used in single-chip mode or memory expansion
mode. The option function select area cannot be used in microprocessor mode. When using the MCU in
microprocessor mode, clear the internal ROM.
0FFFDBh to 0FFFD8h
0FFFFFh to 0FFFFCh
Figure 30.2
Option Function Select Area
R01UH0092EJ0110 Rev.1.10
Jul 31, 2012
Address
OFS1
Reserved area
Reset vector
4 bytes
30. Flash Memory
Page 667 of 807
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