The HK25Q128A is a 128 Megabit (16,384K-byte) Serial Flash memory, with advanced write protection mechanisms. The HK25Q128A supports the single bit and four bits serial input and output commands via standard Serial Peripheral Interface (SPI) pins: Serial Clock, Chip Select, Serial DQ0 (DI) and DQ1(DO), DQ2(WP) and DQ3(HOLD/RESET). SPI clock frequencies of up to 104Mhz are supported allowing equivalent clock rates of 416Mhz(104Mhz x 4) for Quad Output while using the Quad Output read instructions. The memory can be programmed 1 to 256 bytes at a time, using the Page Program instruction. The HK25Q128A also offers a sophisticated method for protecting individual blocks against erroneous or malicious program and erase operations. By providing the ability to individually protect and unprotect blocks, a system can unprotect a specific block to modify its contents while keeping the remaining blocks of the memory array securely protected. This is useful in applications where program code is patched or updated on a subroutine or module basis or in applications where data storage segments need to be modified without running the risk of errant modifications to the program code segments. The HK25Q128A is designed to allow either single Sector/Block at a time or full chip erase operation. The HK25Q128A can be configured to protect part of the memory as the software protected mode. The device can sustain a minimum of 100K program/erase cycles on each sector or block.