John has never learned to read or write. His parents took him to a special school, when one was set up close enough to home to reach. And while he was okay with things like shapes and colours and describing pictures in a rudimentary way, he never learned to recognise letters and reproduce them. His brother sometimes wonders whether better schools, more knowledge of how to teach, something, would have helped, and maybe they—he included—just didn't try enough.
John has a great memory, though, often dredging up little details that his family never remembered until he brought them up. Sometimes it is difficult to figure out what he is referring to, partly because of his slurred speech and limited vocabulary, but also because of the way his mind files away associations. Since he can't always find the right word, or say it clearly if he does, his brother will ask him question after question, going around the problem word, free-associating, playing with related thoughts, until, suddenly, it all falls into place. His brother will say "aha!" and John will say, "that's what I said only!"
John remembers people well. Occasionally, it may seem otherwise, when he refers to X as "Y's wife" or B as "A's father." Until you realise that he will, in another conversation, refer to Y as "X's husband" or A as "B's daughter." His brother has concluded that he remembers people by linking them with others. His brother got that from reading about how peoples without written languages remember things. His brother thinks that was significant. His brother is a little slow sometimes.