It's a mechanically driven distributor. The spark timing is controlled by the computer.

The working spark timing is controlled by the computer, based on the 3 magnetic sensors (CKP, CYP, & TDC) down in the distributor. You've set the base timing (right?), using a timing light.

The computer actually fires the spark plug according to it's spark map, generally before the base timing. At higher rpm & larger throttle-opening, the actual spark timing is more & more advanced. The computer does the job of old-school vacuum advance & centrifugal advance mechanisms. But the job of 'distributing' the spark to each of the 4 spark plugs is still done by the rotor spinning inside the distributor cap.