Reset vector for MB90540GS/5GS(Flash) MCU is fixed. This is called as hard-wired reset.
This function is considered as following.
For no hard-wire reset, reset vector too but only interrupt vector is needed to erase at changing interrupt vector, because sector for interrupt vector and reset vector are same area. When power downs at erasing reset vector, MCU can not be programmed at user programming mode.
If reset vector is fixed, judgment routine, whether user programming routine is selected or not at first of all after reset, can be operated with different sector as interrupt vector. Therefore even if power downs at erasing and programming sector of interrupt vector, reset vector is fetched, and judgment routine, whether user programming routine is selected or not, can be operated.
And FLASH MCU with this function has fixed reset vector even if reset vector is set by software. But MSK MCU is not built this function in, because MASK MCU is not needed hard-wire reset from nature of product.
(Reset vector for MASK MCU is needed to same value as fixed value of FLASH.)