Just started reading Ian Banks' The Culture, and there was this beginning to a chapter:
The Mind had an image to illustrate its information capacity. It liked to imagine the contents of its memory store written out on cards; little slips of paper with tiny writing on them, big enough for a human to read. If the characters were a couple of millimetres tall and the paper about ten centimetres square and written on both sides, then ten thousand characters could be squeezed onto each card. In a metre-long drawer of such cards maybe one thousand of them – ten million pieces of information – could be stored. In a small room a few metres square, with a corridor in the middle just wide enough to pull a tray out into, you could keep perhaps a thousand trays arranged in close-packed cabinets: ten billion characters in all.
A square kilometre of these cramped cells might contain as many as one hundred thousand rooms; a thousand such floors would produce a building two thousand metres tall with a hundred million rooms. If you kept building those squat towers, squeezed hard up against each other until they entirely covered the surface of a largish standard-G world – maybe a billion square kilometres – you would have a planet with one trillion square kilometres of floor space, one hundred quadrillion paper-stuffed rooms, thirty light years of corridors and a number of potential stored characters sufficiently large to boggle just about anybody’s mind.
In base 10 that number would be a 1 followed by twenty-seven zeros, and even that vast figure was only a fraction of the capacity of the Mind. To match it you would need a thousand such worlds; systems of them, a clusterful of information-packed globes…. and that vast a capacity was physically contained within a space smaller than a single one of those tiny rooms, inside the Mind...
How big would that be in gigabytes/petabytes, assuming the 'written text' on the notecards is plain, ascii-encoded text? The reason for that assumption is that if you had
1100001 written on a notecard, it represents the number
97 in base 10, but in ascii it's a lower-case