The M25P40 is a 4 Mbit (512 K × 8) Serial Flash memory, with advanced write protection mechanisms, accessed by a high speed SPI-compatible bus.

The memory can be programmed 1 to 256 bytes at a time, using the Page Program instruction.

The memory is organized as 8 sectors, each containing 256 pages. Each page is 256 bytes wide.

Thus, the whole memory can be viewed as consisting of 2048 pages, or 524,288 bytes.

The whole memory can be erased using the Bulk Erase instruction, or a sector at a time, using the Sector Erase instruction.