The same base plus the performance-linked bonus he was getting for doing most of the data entry with his program. It came to more than what his old boss was making, so it wasn't just data-entry wages.
This doesn't consider the value he's creating for the company. Apparently, the company was willing to part with that money already (before the improvement) - so clearly they should have offered him more for the automation.
The bonus pool he was drawing from was meant to go to an entire team of people, but 90% of it was going to him. His pay ended up being quite a bit higher than what it should have been.