| 摘要 |
A microcomputer capable of reducing a board area, enhancing the security, and improving the usability is provided. A microcomputer to be used in a notebook PC is disclosed, in which programs of a keyboard/power management BIOS and a system BIOS are stored in a built-in flash memory ROM. In order to set read (R)/write (W) protect to the BIOSes stored in the flash memory ROM, a read/write protect setting register is provided, and at initial setting after the release of reset, flags of R/W permission, R permission/W prohibition, W permission/R prohibition, and R/W prohibition are set to this register by a central processing unit CPU. By doing so, it becomes possible to achieve protection such as the prevention of error writing of the BIOS and the like between a host machine and the flash memory ROM via a LPC bus.
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