If I remember correctly, having only played 3 games of AAIB PC, …
at the start of each players turn the opportunity is presented for you to chose how many IPCs(5-10-15-20-25-30-I don’t think you can spend more than that) you wish to spend on tech. For every five you spend the computer will roll 1d6. So if you commit 15 IPCs then 3d6 are rolled. If you get one or more 6(s) on any die/dice it rolls again for you to see what tech you get. If you get no 6s, then you are hurting.
Then the game proceeds allowing you to immediately use any on board units as if they were appropriately upgraded for the tech(s) you developed.
I think.