San Francisco Rush (and probably a lot of other games in seattle.cpp) run slightly faster than it should on pcb. This vid below shows it can be possible to network San Francisco Rush in Mame with an actual pcb but because of said speed issue, the two instances eventually run the race desynchronized.
再現手順
Just play the game.
追加情報
The calibration sequence during boot also runs 2x fast than on pcb too. There has been speed related reports from games in this driver (bug7093 and bug7895). calspeed noticeably runs slightly faster and at a higher frame rate compared to pcb to the point some race finish sequences run 2x fast. Given how much speedier these games run and at higher frame rates in some cases, it's likely a deep MIPS related problem (and fixing it may give a performance drop).
速度
sfrush - サンフランシスコラッシュ -エクストリームレーシング-