Synopsys also offers off-the-shelf memory models for most standard memories, such as SDRAM, DDR, DDR2, DDR3, DDR4, RLDRAM, Mobile DDR, LPDDR2, LPDDR3 and GDDR5, plus a wide variety of Flash and other memory models. These models leverage on-board memory resources of ZeBu, and are completely synchronized with the emulated design, eliminating any issues with timing or refresh cycles. Plus, they are configurable; different memory families (e.g. SDRAM or DDR2) can be implemented in the same ZeBu hardware. No cards/DIMMs need to be plugged or unplugged/added or removed to switch between models. For memories larger than 4 GB, memory transactors that leverage the storage on the host computer are also available.