Calif traffic speedy trial?

If you have proof that you appeared as required, then the 40508 charge will surely be dismissed. Note that you were NOT "convicted in absentia," the only time that can happen is if you have posted bail and then fail to appear. Rost is a very old case, and is not followed now. You can ask for a dismissal on constitutional grounds, but generally you are not going to get a dismissal these days unless the delay was over a year (under a case named "Serna v Superior Court") unless you can show that the delay somehow made it more difficult for you to defend against the charge.