He has no formal education, no qualifications and his reading is only just started to improve through using a mobile, texts from him would make no sense to 90% of people but those who know get it straight away (and its bloody funny sometimes) the best way to put it is simply a clever bloke who just cant read spell or write worth a damn
But he is very switched on, throw numbers at him and he gives you the answer almost before you can finish the question, he also has the ability to see a problem and a simple solution to most things mechanical even though he cant read a manual, stick him in front of a lathe or miller etc and he will work it to perfection and produce whatever you need.
He's been my mate for 40 odd years and the thing that gets me is if we are pissing about with a bike, I will read out carb settings (for example) and he will remember them years later with no prompting, even better if I ask what these jets came out of he will squint at the size and say "oh that was a gsxr1100k" it could have been 20 years since we did that bike and he will still know so its bloody useful