Right. I have a few RDP test roms on my hard drive that my thingie cannot pass, because they need cycle accuracy. Cycle accuracy of the emulated RDP involves, among other things: correct emulation of RDP cycle counter registers; setting different RDP status bits at the correct cycle; synchronizing the RDP and various RDRAM accesses it makes with the RSP, CPU and VI; emulating the effects of absent Sync commands; emulating some interesting anomalies of the LOD unit, particularly in one-cycle mode; calculating the exact cycle when Load commands with certain parameters start DMAing junk into the TMEM and why do they do it; what the hell do RDP span registers do; correct rendering of primitives with certain, unusual properties (spans look completely different to normal primitives, and then the RDP may or may not crash); calculating the exact cycle when the RDP deadlocks, depending on a particular method to achieve that employed by the display list (there are several such methods I'm aware of). If we talk about real cycle accuracy with respect to the RDP, it is also indispensable that we emulate its internal span buffers and all the IO operations that happen with them. The RDP has several DMA engines, so imo for perfect accuracy it's also important to emulate the arbitration mechanisms that resolve conflicts among them.