The technique he's using for wire-wrap is other than what you might expect. Almost all the connections are on the component side.
It's a valid tradeoff for some situations, I suppose. To purchase actual wire-wrap IC sockets would have increased the cost considerably. Instead it seems he used ordinary IC sockets ("solder-tail" style) and added the long pins for wire-wrap afterward.
He's arranged it so the wire-wrap pins pass through the board, and that's why the wiring is up top with the IC's. Unfortunately, that means the wires are longer and more crowded than they might otherwise be, and AC performance will suffer as a result. OTOH having the pins pass through the board adds mechanical strength. The pins need to be fairly secure or else there'll be trouble when you try to wrap the wires on.
If he'd chosen protoboards that feature plate-through holes then securing the pins wouldn't be a problem, and the wiring could go on the bottom. But again there's a cost concern, since plate-through boards are more expensive. It looks to me as if he has considered his options carefully, and is managing rather well!
-- Jeff
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