Trends in storage technology indicate that future notebook, palmtop, and smaller mobile computers will contain battery-backed DRAM as primary storage and direct-mapped hash memory as secondary storage, but no disk. All storage will offer uniform, random access read times through a single-level 64-bit address space. The paper explores the operating system implications of this storage organization. The system should exploit the benefits of having all data reside in fast memory. It can do away with much of the data duplication and related data movement that take place in conventional organizations. The system also needs to hide the limitations of flash memory: Write access times higher than read access times, the need to erase memory before rewriting it, and a limited number of write cycles in the lifetime of the device. It needs to limit write traffic to flash memory and avoid writing repeatedly to the same area of flash memory. These steps will increase performance, improve space utilization, and prolong the life of flash memory.