Non-volatile memory

There are three different schemes for non-volatile data storage in SPLat, meaning the data is preserved even if power goes off. Most schemes are based on FLASH or EEPROM memory technology, though in future we may introduce memory types using battery backup or other technologies. FLASH technology has a wear-out effect, meaning it can only endure a certain number of writes before it ceases working. The various schemes give you a trade-off between size and endurance.

The oldest scheme is called Permanent memory. It consists of 13 bytes, and has a typical endurance of 500,000 writes.

A more recent scheme is called Shadow memory. It allows all of RAM to be backed up (shadowed) into non-volatile memory, but with a lower endurance than Permanent memory. The actual endurance will vary from product to product.

The most recent scheme is Non-Volatile Extended Memory (NVEM). This is a universal model for large non-volatile memories, and was introduced in April 05.