The LE25FU106B is a serial interface-compatible flash memory device with a 128K x 8-bit configuration. It uses a single 2.5V power supply for both reading and writing (program and erase functions) and does not require a special power supply. As such, it can support on-board programming. It has three erase functions, each of which corresponds to the size of the memory area in which the data is to be erased at one time: the small sector (4K bytes) erase function, the sector (32K bytes) erase function, and the chip erase function (for erasing all the data together). The memory space can be efficiently utilized by selecting one of these functions depending on the application. A page program method is supported for data writing. The page program method of the LE25FU106B can program any amount of data from 1 to 256 bytes. The program time of 2.0ms (typ.) when programming 256 bytes (1 page) at one time makes for fast data writing. While making the most of the features inherent to a serial flash memory device, the LE25FU106B is housed in an 8-pin ultra-miniature package. Serial flash memory devices tend to be at a disadvantage in terms of their read speed, but the LE25FU106B has maximally eliminated this speed-related disadvantage by supporting clocks with frequencies up to 30MHz under SPI bus specifications. All these features make this device ideally suited to storing program codes in applications such as portable information devices and small disk systems, which are required to have increasingly more compact dimensions.