Does anyone happen to know the contractors involved with the primary computers in the Shuttles? I was told they used a newer iteration of the Boeing ACUs simila

Does anyone happen to know the contractors involved with the primary computers in the Shuttles? I was told they used a newer iteration of the Boeing ACUs similar to what used to be in the B-52Hs for their Offensive Avionics System. Did they sit on a MIL-STD-1553 bus variant? Any truth to that?