Don't get too jammed up over the tables. The reality is that the last time most divers will ever see a dive table is on their SCUBA written exam.
It's open water diving. If your computer fails, surface with your buddy and end the dive.
Dive Tables are like "brushing your teeth after every meal". Everybody agrees it's a nice idea, but few people actually do it.
Flots has it spot on here. I learned the tables but my computer does the work. If the computer fails, I am done diving that day unless I can fix it. If it cant be easily fixed (battery change) then its time for siesta and cold ones. If I am on vacation, I will rent a computer until its time to come home.
My brain work just fine - most of the time - and I cant remember where the tables are much less the details on it.