The M29W004 is a non-volatile memory that may be erased electrically at the block or chip level and programmed in-system on a Byte-by-Byte basis using only a single 2.7V to 3.6V VCC supply. For Program and Erase operations the necessary high voltages are generated internally. The device can also be programmed in standard programmers. The array matrix organisation allows each block to be erased and reprogrammed without affecting other blocks. Blocks can be protected against programing and erase on programming equipment, and temporarily unprotected to make changes in June 1999