The M58BF008 is a family of 8 Mbit non-volatile Flash memories that can be erased electrically at the block level and programmed in-system. Family members are configured during product testing for a specific Synchronous or Asynchronous Write mode, a Burst default of Wrap or No-wrap and for Critical Word X = 3 or 4 and Burst Word Y = 1 or 2 latency times. The Main memory array matrix allows each of the 32 equal blocks of 256 Kbit to be erased separately and re-programmed without affecting other blocks. The memory features a 256 Kbit Overlay block having the same address space as the first Main memory block. The Overlay block provides a secure storage area that is controlled by special Instructions and an external input. A separate supply VDDQ allows the Input/ Output signals to be at 3.3V levels, while the main supply VDD is 5V.