2.3 Write-Protect (WP)
The Write-Protect (WP) pin will allow normal
            read/write operations when held high. When the WP pin is
            brought low and the WPEN bit is set to a logic ‘1’, all write
            operations to the STATUS register are inhibited. WP going low
            while CS is still low will interrupt a write operation to the
            STATUS register. If the internal write cycle has already been initiated,
                WP going low will have no effect on any write operation to
            the STATUS register. The WP pin function is blocked when the
            WPEN bit in the STATUS register is set to a logic ‘0’. This will allow
            the user to install the AT25128B/AT25256B in a system with the
                WP pin tied to ground and still be able to write to the
            STATUS register. All WP pin functions are enabled when the WPEN
            bit is set to a logic ‘1’.
