More recent GPU families such as Fermi and Kepler have adopted CPU-style virtual memory architecture with a____________-bit virtual address space and a physical address space of at least 40 bits. The obvious benefit is that Fermi and Kepler GPUs can incorporate more than 4 gigabytes of DRAM and that CUDA kernels can now operate on very large data sets, whether hosted entirely in on-board GPU DRAM, or by accessing mapped host memory.