The Bulova Accuquartz is the only example of a quartz controlled tuning fork that was ever produced. The Longines Ultra-Quartz has many similarities but is not the same and is considerably more complex.
In the Accuquartz, the tuning fork has become “passive” and is no longer responsible for regulating the watch; it is only there to drive the hands via the unchanged indexing mechanism. However, the adjusters on the tuning fork cups still need to be “tuned” to the quartz to ensure optimum battery consumption.
Instead, the movement is regulated by either engaging or dis-engaging internal capacitors in the quartz circuitry; this is achieved by small brass screws which are either added or removed from the 6 small holes on the left hand side of the movement — you can see these in the last photograph.