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When option function select register 1 (OFS1) is modified by an operation other than downloading (e.g. editing through the Memory panel or line assembling), the following steps are necessary to make the new setting take effect.
(1) Modify OFS1.
(2) Start user program execution (write access to OFS1 occurs).
(3) Reset the CPU.
When OFS1 is modified by downloading, the new setting takes effect when the CPU is reset after the downloading.

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Option function select register 1 (OFS1) allows you to enable or disable a voltage monitoring 0 reset and set a voltage detection level. This register is located in the flash memory, so be aware that depending on settings, it may not be controlled by E1/E20/EZ Emulator. When the flash ROM contents are modified (by downloading or through the Memory panel), if option function select register 1 (OFS1) is set to a condition that generates a voltage monitoring 0 reset, an error will occur. See the hardware manual of the microcontroller for the details of the option function select register 1 (OFS1).

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When CS+ is started up to initiate FINE communication, the emulator forcibly sets bits 25 and 24 in the OFS1 register to 10b. In this case, ensure that the user program does not write to bits 25 and 24.