Suspect a failed distributor igniter or pick-up, a common cause of no spark on these Mazda distributors. The igniter/pick-up is in the distributor and, if faulty, will not signal the coil to fire. Confirm that diagnosis before replacing the computer or buying another expensive part.
A 1996 Mazda 626 2.0L cranks and has power but will not fire, with no spark after the coil, plugs, wires, and rotor were replaced and fuses checked. A 1991 Mazda 626 2.2L owner reported the same no-spark condition after replacing the coil, wires, cap, and rotor, with fuel and coil voltage present. The Mazda tech said both cases most likely involve a faulty distributor igniter or pick-up that fails to trigger the coil. The 1996 owner then asked whether that part is inside the distributor and whether the whole distributor must be replaced.
