Abstraction of time is one of the most important issues in device modeling. Simics already abstracts away some details of the timing of instruction execution and scheduling in the processor, to achieve better performance; see the Simics User Guide, "Advanced Simics Usage: Understanding Simics Timing", for more information.
Modern device drivers are often written to be largely independent of the detailed timing of the hardware. This means the device model can alter the timing behavior quite a bit without the driver noticing.
7.1 Provide Reaction Immediately
7.3 Transform Events into Functions of Time