One embodiment of a non-volatile memory system comprises block-accessible non-volatile memory, random access memory arranged to be linearly addressable by a processor as part of the processor's memory address space, to be read from and written to by the processor, and logic interposed between the block-accessible non-volatile memory and the random access memory and arranged to write parts of the content of the random access memory in blocks to blocks of the non-volatile, block-accessible memory. The logic is arranged to monitor processor writes to the random access memory, and to write blocks of the random access memory that differ from a most recent copy in the non-volatile, block-accessible memory to the non-volatile, block-accessible memory.