Complex sentence: In February 2009, Samsung validated 40 nm DRAM chips, considered a "significant step" towards DDR4 development since as of 2009, current DRAM chips were only beginning to migrate to a 50 nm process.
Split into simpler sentences: In February 2009, Samsung validated 40 nm DRAM chips, considered a "significant step" towards DDR4 development. As of 2009, current DRAM chips are only migrating to a 50 nm process.