The M27W800 is a low voltage 8 Mbit EPROM offered in the two ranges UV (ultra violet erase) and OTP (one time programmable). It is ideally suited for microprocessor systems requiring large data or program storage. It is organised as either 1 Mbit words of 8 bit or 512 Kbit words of 16 bit. The pinout is compatible with a 8 Mbit Mask ROM. The M27W800 operates in the read mode with a supply voltage as low as 2.7V. The decrease in operating power allows either a reduction of the size of the battery or an increase in the time between battery recharges. The FDIP42W (window ceramic frit-seal package) has a transparent lid which allows the user to expose the chip to ultraviolet light to erase the bit pattern. A new pattern can then be written rapidly to the device by following the programming procedure. For applications where the content is programmed only one time and erasure is not required, the M27W800 is offered in PDIP42 and PLCC44 package.