The SimNow™ simulator is a fast and configurable x86 and AMD64 dynamically-translating instruction-level platform simulator. With SimNow users can connect complex software models to form a PC platform emulation environment. SimNow™ emulates AMD Athlon™ 64 and AMD Opteron™ uniprocessor and multiprocessor based systems that run several commercial operating systems and applications. Specifically, AMD and its partners use SimNow™ for:

• BIOS and device driver development.
• Prototyping software visible architectural changes.
• Non-intrusive and deterministic measurement and testing of software at the instruction-level.
• Modeling of future platform tradeoffs for correctness and performance analysis.

The simulator contains all the classic pieces of a PC system (CPU, memory, Northbridge, Southbridge, display, IDE drives, floppy, keyboard, and mouse support). Images (hard disk, DVD/CD-ROM, and floppy) can be created in custom sizes with the DiskTool program that is provided with the simulator. A simulation can be saved at any point in the simulation to a media file, from which the simulation can be re-run at a later time.

The configuration of the simulated system (how models are connected together and their settings) and the logical state of all the devices in the simulator are saved in a 'BSD' file format. When starting a simulation from reset, the 'BSD' file is rather small and only contains the configuration information. When the simulation starts running, the simulated memory is allocated and the 'BSD' file size grows significantly, slightly larger than the size of simulated memory.